Wavelength-tunable organic semiconductor lasers based on mechanically stretchable polydimethylsiloxane (PDMS) gratings were developed. The intrinsic stretchability of PDMS was explored to modulate the period of the di...Wavelength-tunable organic semiconductor lasers based on mechanically stretchable polydimethylsiloxane (PDMS) gratings were developed. The intrinsic stretchability of PDMS was explored to modulate the period of the distributed feedback gratings for fine tuning the lasing wavelength. Notably, elastic lasers based on three typical light-emitting molecules show com-parable lasing threshold values analogous to rigid devices and a continuous wavelength tunability of about 10 nm by mechanic-al stretching. In addition, the stretchability provides a simple solution for dynamically tuning the lasing wavelength in a spec-tral range that is challenging to achieve for inorganic counterparts. Our work has provided a simple and efficient method of fab-ricating tunable organic lasers that depend on stretchable distributed feedback gratings, demonstrating a significant step in the advancement of flexible organic optoelectronic devices.展开更多
We propose a theoretical model to describe external-cavity distributed feedback semiconductor lasers and investigate the impact of the number of external feedback points on linewidth and side-mode suppression ratio th...We propose a theoretical model to describe external-cavity distributed feedback semiconductor lasers and investigate the impact of the number of external feedback points on linewidth and side-mode suppression ratio through numerical simulation. The simulation results demonstrate that the linewidth of external-cavity semiconductor lasers can be reduced by increasing the external cavity length and feedback ratio, and adding more external feedback points can further narrow the linewidth and enhance the side mode suppression ratio. This research provides insight into the external cavity distributed feedback mechanism and can guide the design of high-performance external cavity semiconductor lasers. .展开更多
A fitting process is used to measure the cavity loss and the quasi Fermi level separation for Fabry Pérot semiconductor lasers.From the amplified spontaneous emission (ASE) spectrum,the gain spectrum and sing...A fitting process is used to measure the cavity loss and the quasi Fermi level separation for Fabry Pérot semiconductor lasers.From the amplified spontaneous emission (ASE) spectrum,the gain spectrum and single pass ASE obtained by the Cassidy method are applied in the fitting process.For a 1550nm quantum well InGaAsP ridge waveguide laser,the cavity loss of about ～24cm -1 is obtained.展开更多
We solve the single mode coupled rate equations by computer,simulate the behavior of a gain switch of an AlGaInP red light semiconductor laser diode,and find the characteristic of FWHM of pulses changing with the ampl...We solve the single mode coupled rate equations by computer,simulate the behavior of a gain switch of an AlGaInP red light semiconductor laser diode,and find the characteristic of FWHM of pulses changing with the amplitude of modulation signal, the bias current, and the modulated frequency. On this basis, we conduct experiments. The experiment results accord with the simulations well.展开更多
Based on a semiconductor laser （SL） with incoherent optical feedback, a novel all-optical scheme for generating tunable and broadband microwave frequency combs （MFCs） is proposed and investigated numerically. The ...Based on a semiconductor laser （SL） with incoherent optical feedback, a novel all-optical scheme for generating tunable and broadband microwave frequency combs （MFCs） is proposed and investigated numerically. The results show that, under suitable operation parameters, the SL with incoherent optical feedback can be driven to operate at a regular pulsing state, and the generated MFCs have bandwidths broader than 40 GHz within a 10 dB amplitude variation. For a fixed bias current, the line spacing （or repetition frequency） of the MFCs can be easily tuned by varying the feedback delay time and the feedback strength, and the tuning range of the line spacing increases with the increase in the bias current. The linewidth of the MFCs is sensitive to the variation of the feedback delay time and the feedback strength, and a linewidth of tens of KHz can be achieved through finely adjusting the feedback delay time and the feedback strength. In addition, mappings of amplitude variation, repetition frequency, and linewidth of MFCs in the parameter space of the feedback delay time and the feedback strength are presented.展开更多
Narrow linewidth light source is a prerequisite for high-performance coherent optical communication and sensing.Waveguide-based external cavity narrow linewidth semiconductor lasers(WEC-NLSLs)have become a competitive...Narrow linewidth light source is a prerequisite for high-performance coherent optical communication and sensing.Waveguide-based external cavity narrow linewidth semiconductor lasers(WEC-NLSLs)have become a competitive and attractive candidate for many coherent applications due to their small size,volume,low energy consumption,low cost and the ability to integrate with other optical components.In this paper,we present an overview of WEC-NLSLs from their required technologies to the state-of-the-art progress.Moreover,we highlight the common problems occurring to current WEC-NLSLs and show the possible approaches to resolving the issues.Finally,we present the possible development directions for the next phase and hope this review will be beneficial to the advancements of WEC-NLSLs.展开更多
We design a hybrid integrated chaotic semiconductor laser with short-cavity optical feedback.It can be assembled in a commercial butterfly shell with just three micro-lenses.One of them is coated by a transflective fi...We design a hybrid integrated chaotic semiconductor laser with short-cavity optical feedback.It can be assembled in a commercial butterfly shell with just three micro-lenses.One of them is coated by a transflective film to provide the optical feedback for chaos generation while insuring regular laser transmission.We prove the feasibility of the chaos generation in this compact structure and provide critical external parameters for the fabrication by theoretical simulations.Rather than the usual changeless internal parameters used in previous simulation research,we extract the real parameters of the chip by experiment.Moreover,the maps of the largest Lyapunov exponent with varying bias current and feedback intensity Kap demonstrate the dynamic characteristics under different external-cavity conditions.Each laser chip has its own optimal external cavity length(L)and feedback intensity(Kap)to generate chaos because of the different internal parameters.We have acquired two ranges of optimal parameters(L=4 mm,0.12〈Kap〈0.2 and L=5 mm,0.07〈Kap〈0.12)for two different chips.展开更多
Based on the rate equations, we have investigated three types of chaos synchronizations in injection-locked semiconductor lasers with optical feedback. Numerical simulation shows that the synchronization can be realiz...Based on the rate equations, we have investigated three types of chaos synchronizations in injection-locked semiconductor lasers with optical feedback. Numerical simulation shows that the synchronization can be realized by the symmetric or asymmetric laser systems. Also, the influence of parameter mismatches on chaos synchronization is investigated, and the results imply that these two lasers can achieve good synchronization, with smaller tolerance of parameter mismatch existing.展开更多
The optical catastrophic damage that usually occurs at the cavity surface of semiconductor lasers has become the main bottleneck affecting the improvement of laser output power and long-term reliability.To improve the...The optical catastrophic damage that usually occurs at the cavity surface of semiconductor lasers has become the main bottleneck affecting the improvement of laser output power and long-term reliability.To improve the output power of 680 nm AlGaInP/GaInP quantum well red semiconductor lasers,Si-Si_(3)N_(4)composited dielectric layers are used to induce its quantum wells to be intermixed at the cavity surface to make a non-absorption window.Si with a thickness of 100 nm and Si_(3)N_(4)with a thickness of 100 nm were grown on the surface of the epitaxial wafer by magnetron sputtering and PECVD as diffusion source and driving source,respectively.Compared with traditional Si impurity induced quantum well intermixing,this paper realizes the blue shift of 54.8 nm in the nonabsorbent window region at a lower annealing temperature of 600 ℃ and annealing time of 10 min.Under this annealing condition,the wavelength of the gain luminescence region basically does not shift to short wavelength,and the surface morphology of the whole epitaxial wafer remains fine after annealing.The application of this process condition can reduce the difficulty of production and save cost,which provides an effective method for upcoming fabrication.展开更多
We introduce a new method of simultaneously implementing frequency stabilization and frequency shift for semiconductor lasers. We name this method the frequency tunable modulation transfer spectroscopy （FTMTS）. To r...We introduce a new method of simultaneously implementing frequency stabilization and frequency shift for semiconductor lasers. We name this method the frequency tunable modulation transfer spectroscopy （FTMTS）. To realize a stable output of 780 nm semiconductor laser, an FTMTS optical heterodyne frequency stabilization system is constructed. Before entering into the frequency stabilization system, the probe laser passes through an acousto-optical modulator （AOM） twice in advance to achieve tunable frequency while keeping the light path stable. According to the experimental results, the frequency changes from 120 MHz to 190 MHz after the double-pass AOM, and the intensity of laser entering into the system is greatly changed, but there is almost no change in the error signal of the FTMTS spectrum. Using this signal to lock the laser frequency, we can ensure that the frequency of the laser changes with the amount of AOM shift. Therefore, the magneto-optical trap （MOT）-molasses process can be implemented smoothly.展开更多
Internal loss is a key internal parameter for high power 1060-nm InGaAs/A1GaAs semiconductor laser. In this paper, we discuss the origin of internal loss of 1060-nm InGaAs/GaAs quantum welt （QW） AIGaAs separate conf...Internal loss is a key internal parameter for high power 1060-nm InGaAs/A1GaAs semiconductor laser. In this paper, we discuss the origin of internal loss of 1060-nm InGaAs/GaAs quantum welt （QW） AIGaAs separate confinement het- erostructure semiconductor laser, and the method to reduce internal loss. By light doping the n-cladding layer, and stepwise doping the p-cladding layer combined with the expanded waveguide layer, a broad area laser with internal loss of 1/cm is designed and fabricated. Ridge waveguide laser with an output power of 350 mW is obtained. The threshold current and slope efficiency near the threshold current are 20 mA and 0.8 W/A, respectively.展开更多
Polarization switching （PS） dynamics and synchronization performances of two mutually coupled vertical-cavity surface-emitting lasers （VCSELs） are studied theoretically in this paper. A group of dimensionless rate...Polarization switching （PS） dynamics and synchronization performances of two mutually coupled vertical-cavity surface-emitting lasers （VCSELs） are studied theoretically in this paper. A group of dimensionless rate equations is derived to describe our model. While analysing the PS characteristics, we focus on the effects of coupling rate and frequency detuning regarding different mutual injection types. The results indicate that the x-mode injection defers the occurrence of PS, while the y-mode injection leads the PS to occur at a lower current. Strong enough polarization-selective injection can suppress the PS. Moreover, if frequency detuning is considered, the effects of polarization-selective mutual injection will be weakened. To evaluate the synchronization performance, the correlation coefficients and output dynamics of VCSELs with both pure mode and mixed mode polarizations are given. It is found that performance of complete synchronization is sensitive to the frequency mismatch but it is little affected by mixed mode polarizations, which is opposite to the case of injection-locking synchronization.展开更多
A monolithically active-passive integrated colliding pulse mode-locked semiconductor laser is demonstrated in the InGaAsP//InP material system. The device is mode locked at the second harmonic passive mode-locking reg...A monolithically active-passive integrated colliding pulse mode-locked semiconductor laser is demonstrated in the InGaAsP//InP material system. The device is mode locked at the second harmonic passive mode-locking regime with a wide mode-locking range. Pulse trains with the repetition rate of 40 GHz, 3-dB rf line width of 25 kHz, the pulse width of 2.5 ps, and a nearly transform-limited time-bandwidth product of 0.53 are obtained.展开更多
This paper investigates the influences of a semiconductor laser with narrow linewidth on a fibre-optic distributed disturbance sensor based on Mach-Zehnder interferometer. It establishes an effective numerical model t...This paper investigates the influences of a semiconductor laser with narrow linewidth on a fibre-optic distributed disturbance sensor based on Mach-Zehnder interferometer. It establishes an effective numerical model to describe the noises and linewidth of a semiconductor laser, taking into account their correlations. Simulation shows that frequency noise has great influences on location errors and their relationship is numerically investigated. Accordingly, there is need to determine the linewidth of the laser less than a threshold and obtain the least location errors. Furthermore, experiments are performed by a sensor prototype using three semiconductor lasers with different linewidths, respectively, with polarization maintaining optical fibres and couplers to eliminate the polarization induced noises and fading. The agreement of simulation with experimental results means that the proposed numerical model can make a comprehensive description of the noise behaviour of a semiconductor laser. The conclusion is useful for choosing a laser source for fibre-optic distributed disturbance sensor to achieve optimized location accuracy. What is more, the proposed numerical model can be widely used for analysing influences of semiconductor lasers on other sensing, communication and optical signal processing systems.展开更多
We use traveling wave coupling theory to investigate the time domain characteristics of tapered semiconductor lasers with DBR gratings.We analyze the influence of the length of second order gratings on the power and s...We use traveling wave coupling theory to investigate the time domain characteristics of tapered semiconductor lasers with DBR gratings.We analyze the influence of the length of second order gratings on the power and spectrum of output light,and optimizing the length of gratings,in order to reduce the mode competition effect in the device,and obtain the high power output light wave with good longitudinal mode characteristics.展开更多
This paper is focused on a 940 nm edge type of semiconductor laser, which is made from 940 nm InGaAs double-quantum-well epitaxial wafer, produced by Metal Organic Chemical Vapor Deposition (MOCVD). In the absence of ...This paper is focused on a 940 nm edge type of semiconductor laser, which is made from 940 nm InGaAs double-quantum-well epitaxial wafer, produced by Metal Organic Chemical Vapor Deposition (MOCVD). In the absence of coating, the efficiency at the room temperature is 0.89 W/A, and the averaged threshold current is 0.307 A. The present study investigates the impact of temperature on the P-I curve, V-I curve and the centre wavelength, the temperature ranging from 286.15 - 333.15 K. It shows that the threshold current increases from 0.28 A to 0.41 A with the increasing temperature. The increase rate is 0.0027 A/K. With the temperature ranging from 286.15 - 333.15 K, the characteristic temperature is calculated to be 120 K. At driven current of 2 A, the output power decreases from 1.47 W to 1.27 W at a rate of 0.00425 W/K. At a constant voltage, the output current initially increases with the temperature within a certain range, beyond which the impact of the temperature is minimum. The ideal factor obtained from V-I curve by curve fitting is 1.076. The series resistance is 0.609 Ω. The centre wavelength shifts to a longer wavelength with the increasing temperature at a rate of 0.275288 nm/K.展开更多
This paper numerically demonstrates synchronization and bidirectional communication without delay line by using two semiconductor lasers with strong mutual injection in a face-to-face configuration. These results show...This paper numerically demonstrates synchronization and bidirectional communication without delay line by using two semiconductor lasers with strong mutual injection in a face-to-face configuration. These results show that both of the two lasers＇ outputs synchronize with their input chaotic carriers. In addition, simulations demonstrate that this kind of synchronization can be used to realize bidirectional communications without delay line. Further studies indicate that within a small deviation in message amplitudes of two sides （±6%）, the message can be extracted with signal-noise-ratio more than 10 dB; and the signal-noise-ratio is extremely sensitive to the message rates mismatch of two sides, which may be used as a key of bidirectional communication.展开更多
Square microcavities, which support whispering-gallery modes with total internal reflections, can be employed as high-quality laser resonators for fabricating compact, low-threshold semiconductor lasers. In this paper...Square microcavities, which support whispering-gallery modes with total internal reflections, can be employed as high-quality laser resonators for fabricating compact, low-threshold semiconductor lasers. In this paper, we review the recent progress of square microcavity semiconductor lasers. The characteristics of confined optical modes in the square microcavities are introduced briefly. Based on the mode properties of the square microcavities, dual-mode lasers with tunable wavelength intervals are realized for generating microwave signals. Furthermore, deformed square microcavity lasers with the sidewalls replaced by circular sides are proposed and experimentally demonstrated to enhance the mode confinement and increase the dual-mode interval to the THz range. In order to further reduce the device size, metal-confined wavelength-scale square cavity lasers are also demonstrated.展开更多
The semiconductor laser array with single-mode emission is presented in this paper.The 6-μm-wide ridge waveguides(RWGs)are fabricated to select the lateral mode.Thus the fundamental mode of laser array can be obtaine...The semiconductor laser array with single-mode emission is presented in this paper.The 6-μm-wide ridge waveguides(RWGs)are fabricated to select the lateral mode.Thus the fundamental mode of laser array can be obtained by the RWGs.And the maximum output power of single-mode emission can reach 36 W at an injection current of 43 A,after that,a kink will appear.The slow axis(SA)far-field divergence angle of the unit is 13.65.The beam quality factor M;of the units determined by the second-order moment(SOM)method,is 1.2.This single-mode emission laser array can be used for laser processing.展开更多
We utilize three parallel reservoir computers using semiconductor lasers with optical feedback and light injection to model radar probe signals with delays.Three radar probe signals are generated by driving lasers con...We utilize three parallel reservoir computers using semiconductor lasers with optical feedback and light injection to model radar probe signals with delays.Three radar probe signals are generated by driving lasers constructed by a threeelement laser array with self-feedback.The response lasers are implemented also by a three-element lase array with both delay-time feedback and optical injection,which are utilized as nonlinear nodes to realize the reservoirs.We show that each delayed radar probe signal can be predicted well and to synchronize with its corresponding trained reservoir,even when parameter mismatches exist between the response laser array and the driving laser array.Based on this,the three synchronous probe signals are utilized for ranging to three targets,respectively,using Hilbert transform.It is demonstrated that the relative errors for ranging can be very small and less than 0.6%.Our findings show that optical reservoir computing provides an effective way for applications of target ranging.展开更多
基金financial support from the National Natural Science Foundation of China (21835003, 91833304,21422402, 62274097, 21674050, 62004106)the National Key Basic Research Program of China (2014CB648300,2017YFB0404501)+11 种基金the Natural Science Foundation of Jiangsu Province (BE2019120, BK20160888)Program for Jiangsu Specially-Appointed Professor (RK030STP15001)the Six Talent Peaks Project of Jiangsu Province (TD-XCL-009)the333 Project of Jiangsu Province (BRA2017402)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (20KJB140005)China Postdoctoral Science Foundation (2020M671553)the NUPT"1311 Project"and Scientific Foundation (NY217169, NY215062, NY215107,NY217087)the Leading Talent of Technological Innovation of National Ten-Thousands Talents Program of Chinathe Excellent Scientific and Technological Innovative Teams of Jiangsu Higher Education Institutions (TJ217038)the Postgraduate Research&Practice Innovation Program of Jiangsu Province (SJCX21-0297)the Synergetic Innovation Center for Organic Electronics and Information Displaysthe Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘Wavelength-tunable organic semiconductor lasers based on mechanically stretchable polydimethylsiloxane (PDMS) gratings were developed. The intrinsic stretchability of PDMS was explored to modulate the period of the distributed feedback gratings for fine tuning the lasing wavelength. Notably, elastic lasers based on three typical light-emitting molecules show com-parable lasing threshold values analogous to rigid devices and a continuous wavelength tunability of about 10 nm by mechanic-al stretching. In addition, the stretchability provides a simple solution for dynamically tuning the lasing wavelength in a spec-tral range that is challenging to achieve for inorganic counterparts. Our work has provided a simple and efficient method of fab-ricating tunable organic lasers that depend on stretchable distributed feedback gratings, demonstrating a significant step in the advancement of flexible organic optoelectronic devices.
文摘We propose a theoretical model to describe external-cavity distributed feedback semiconductor lasers and investigate the impact of the number of external feedback points on linewidth and side-mode suppression ratio through numerical simulation. The simulation results demonstrate that the linewidth of external-cavity semiconductor lasers can be reduced by increasing the external cavity length and feedback ratio, and adding more external feedback points can further narrow the linewidth and enhance the side mode suppression ratio. This research provides insight into the external cavity distributed feedback mechanism and can guide the design of high-performance external cavity semiconductor lasers. .
文摘A fitting process is used to measure the cavity loss and the quasi Fermi level separation for Fabry Pérot semiconductor lasers.From the amplified spontaneous emission (ASE) spectrum,the gain spectrum and single pass ASE obtained by the Cassidy method are applied in the fitting process.For a 1550nm quantum well InGaAsP ridge waveguide laser,the cavity loss of about ～24cm -1 is obtained.
文摘We solve the single mode coupled rate equations by computer,simulate the behavior of a gain switch of an AlGaInP red light semiconductor laser diode,and find the characteristic of FWHM of pulses changing with the amplitude of modulation signal, the bias current, and the modulated frequency. On this basis, we conduct experiments. The experiment results accord with the simulations well.
基金supported by the National Natural Science Foundation of China(Grant Nos.61178011,11204248,61475127,and 61275116)the Natural Science Foundation of Chongqing City,China(Grant Nos.2012jj B40011 and 2012jj A40012)the Open Fund of the State Key Lab of Millimeter Waves of China(Grant No.K201418)
文摘Based on a semiconductor laser （SL） with incoherent optical feedback, a novel all-optical scheme for generating tunable and broadband microwave frequency combs （MFCs） is proposed and investigated numerically. The results show that, under suitable operation parameters, the SL with incoherent optical feedback can be driven to operate at a regular pulsing state, and the generated MFCs have bandwidths broader than 40 GHz within a 10 dB amplitude variation. For a fixed bias current, the line spacing （or repetition frequency） of the MFCs can be easily tuned by varying the feedback delay time and the feedback strength, and the tuning range of the line spacing increases with the increase in the bias current. The linewidth of the MFCs is sensitive to the variation of the feedback delay time and the feedback strength, and a linewidth of tens of KHz can be achieved through finely adjusting the feedback delay time and the feedback strength. In addition, mappings of amplitude variation, repetition frequency, and linewidth of MFCs in the parameter space of the feedback delay time and the feedback strength are presented.
基金Jiangsu Province Key R&D Program(Industry Prospect and Common Key Technologies)(No.BE2014083)Jiangxi Natural Science Foundation Project(No.2019ACBL20054)。
文摘Narrow linewidth light source is a prerequisite for high-performance coherent optical communication and sensing.Waveguide-based external cavity narrow linewidth semiconductor lasers(WEC-NLSLs)have become a competitive and attractive candidate for many coherent applications due to their small size,volume,low energy consumption,low cost and the ability to integrate with other optical components.In this paper,we present an overview of WEC-NLSLs from their required technologies to the state-of-the-art progress.Moreover,we highlight the common problems occurring to current WEC-NLSLs and show the possible approaches to resolving the issues.Finally,we present the possible development directions for the next phase and hope this review will be beneficial to the advancements of WEC-NLSLs.
基金Project supported by the International Science and Technology Cooperation Program of China(Grant No.2014DFA50870)the National Natural Science Foundation of China(Grant Nos.61377089,61475111,and 61527819)+4 种基金Shanxi Province Natural Science Foundation,China(Grant No.2015011049)Shanxi Province Youth Science and Technology Foundation,China(Grant No.201601D021069)Shanxi Scholarship Council of China(Grant No.2016-036)Program for the Outstanding Innovative Teams of Higher Learning Institutions of Shanxi,ChinaProgram for Sanjin Scholar,China
文摘We design a hybrid integrated chaotic semiconductor laser with short-cavity optical feedback.It can be assembled in a commercial butterfly shell with just three micro-lenses.One of them is coated by a transflective film to provide the optical feedback for chaos generation while insuring regular laser transmission.We prove the feasibility of the chaos generation in this compact structure and provide critical external parameters for the fabrication by theoretical simulations.Rather than the usual changeless internal parameters used in previous simulation research,we extract the real parameters of the chip by experiment.Moreover,the maps of the largest Lyapunov exponent with varying bias current and feedback intensity Kap demonstrate the dynamic characteristics under different external-cavity conditions.Each laser chip has its own optimal external cavity length(L)and feedback intensity(Kap)to generate chaos because of the different internal parameters.We have acquired two ranges of optimal parameters(L=4 mm,0.12〈Kap〈0.2 and L=5 mm,0.07〈Kap〈0.12)for two different chips.
文摘Based on the rate equations, we have investigated three types of chaos synchronizations in injection-locked semiconductor lasers with optical feedback. Numerical simulation shows that the synchronization can be realized by the symmetric or asymmetric laser systems. Also, the influence of parameter mismatches on chaos synchronization is investigated, and the results imply that these two lasers can achieve good synchronization, with smaller tolerance of parameter mismatch existing.
基金supported by the National Natural Science Foundation of China(NNSFC)(Grant No.62174154).
文摘The optical catastrophic damage that usually occurs at the cavity surface of semiconductor lasers has become the main bottleneck affecting the improvement of laser output power and long-term reliability.To improve the output power of 680 nm AlGaInP/GaInP quantum well red semiconductor lasers,Si-Si_(3)N_(4)composited dielectric layers are used to induce its quantum wells to be intermixed at the cavity surface to make a non-absorption window.Si with a thickness of 100 nm and Si_(3)N_(4)with a thickness of 100 nm were grown on the surface of the epitaxial wafer by magnetron sputtering and PECVD as diffusion source and driving source,respectively.Compared with traditional Si impurity induced quantum well intermixing,this paper realizes the blue shift of 54.8 nm in the nonabsorbent window region at a lower annealing temperature of 600 ℃ and annealing time of 10 min.Under this annealing condition,the wavelength of the gain luminescence region basically does not shift to short wavelength,and the surface morphology of the whole epitaxial wafer remains fine after annealing.The application of this process condition can reduce the difficulty of production and save cost,which provides an effective method for upcoming fabrication.
基金Project supported by the National Key Scientific Instrument and Equipment Development Project,China(Grant No.2014YQ35046103)
文摘We introduce a new method of simultaneously implementing frequency stabilization and frequency shift for semiconductor lasers. We name this method the frequency tunable modulation transfer spectroscopy （FTMTS）. To realize a stable output of 780 nm semiconductor laser, an FTMTS optical heterodyne frequency stabilization system is constructed. Before entering into the frequency stabilization system, the probe laser passes through an acousto-optical modulator （AOM） twice in advance to achieve tunable frequency while keeping the light path stable. According to the experimental results, the frequency changes from 120 MHz to 190 MHz after the double-pass AOM, and the intensity of laser entering into the system is greatly changed, but there is almost no change in the error signal of the FTMTS spectrum. Using this signal to lock the laser frequency, we can ensure that the frequency of the laser changes with the amount of AOM shift. Therefore, the magneto-optical trap （MOT）-molasses process can be implemented smoothly.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61274046,61335009,61201103,and 61320106013)the National High Technology Research and Development Program of China(Grant No.2013AA014202)
文摘Internal loss is a key internal parameter for high power 1060-nm InGaAs/A1GaAs semiconductor laser. In this paper, we discuss the origin of internal loss of 1060-nm InGaAs/GaAs quantum welt （QW） AIGaAs separate confinement het- erostructure semiconductor laser, and the method to reduce internal loss. By light doping the n-cladding layer, and stepwise doping the p-cladding layer combined with the expanded waveguide layer, a broad area laser with internal loss of 1/cm is designed and fabricated. Ridge waveguide laser with an output power of 350 mW is obtained. The threshold current and slope efficiency near the threshold current are 20 mA and 0.8 W/A, respectively.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10174057 and 90201011）, and the Foundation for Key Program of Ministry of Education, China （Grant No 2005-105148）.
文摘Polarization switching （PS） dynamics and synchronization performances of two mutually coupled vertical-cavity surface-emitting lasers （VCSELs） are studied theoretically in this paper. A group of dimensionless rate equations is derived to describe our model. While analysing the PS characteristics, we focus on the effects of coupling rate and frequency detuning regarding different mutual injection types. The results indicate that the x-mode injection defers the occurrence of PS, while the y-mode injection leads the PS to occur at a lower current. Strong enough polarization-selective injection can suppress the PS. Moreover, if frequency detuning is considered, the effects of polarization-selective mutual injection will be weakened. To evaluate the synchronization performance, the correlation coefficients and output dynamics of VCSELs with both pure mode and mixed mode polarizations are given. It is found that performance of complete synchronization is sensitive to the frequency mismatch but it is little affected by mixed mode polarizations, which is opposite to the case of injection-locking synchronization.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61335009,61274046 and 61474111
文摘A monolithically active-passive integrated colliding pulse mode-locked semiconductor laser is demonstrated in the InGaAsP//InP material system. The device is mode locked at the second harmonic passive mode-locking regime with a wide mode-locking range. Pulse trains with the repetition rate of 40 GHz, 3-dB rf line width of 25 kHz, the pulse width of 2.5 ps, and a nearly transform-limited time-bandwidth product of 0.53 are obtained.
文摘This paper investigates the influences of a semiconductor laser with narrow linewidth on a fibre-optic distributed disturbance sensor based on Mach-Zehnder interferometer. It establishes an effective numerical model to describe the noises and linewidth of a semiconductor laser, taking into account their correlations. Simulation shows that frequency noise has great influences on location errors and their relationship is numerically investigated. Accordingly, there is need to determine the linewidth of the laser less than a threshold and obtain the least location errors. Furthermore, experiments are performed by a sensor prototype using three semiconductor lasers with different linewidths, respectively, with polarization maintaining optical fibres and couplers to eliminate the polarization induced noises and fading. The agreement of simulation with experimental results means that the proposed numerical model can make a comprehensive description of the noise behaviour of a semiconductor laser. The conclusion is useful for choosing a laser source for fibre-optic distributed disturbance sensor to achieve optimized location accuracy. What is more, the proposed numerical model can be widely used for analysing influences of semiconductor lasers on other sensing, communication and optical signal processing systems.
文摘We use traveling wave coupling theory to investigate the time domain characteristics of tapered semiconductor lasers with DBR gratings.We analyze the influence of the length of second order gratings on the power and spectrum of output light,and optimizing the length of gratings,in order to reduce the mode competition effect in the device,and obtain the high power output light wave with good longitudinal mode characteristics.
文摘This paper is focused on a 940 nm edge type of semiconductor laser, which is made from 940 nm InGaAs double-quantum-well epitaxial wafer, produced by Metal Organic Chemical Vapor Deposition (MOCVD). In the absence of coating, the efficiency at the room temperature is 0.89 W/A, and the averaged threshold current is 0.307 A. The present study investigates the impact of temperature on the P-I curve, V-I curve and the centre wavelength, the temperature ranging from 286.15 - 333.15 K. It shows that the threshold current increases from 0.28 A to 0.41 A with the increasing temperature. The increase rate is 0.0027 A/K. With the temperature ranging from 286.15 - 333.15 K, the characteristic temperature is calculated to be 120 K. At driven current of 2 A, the output power decreases from 1.47 W to 1.27 W at a rate of 0.00425 W/K. At a constant voltage, the output current initially increases with the temperature within a certain range, beyond which the impact of the temperature is minimum. The ideal factor obtained from V-I curve by curve fitting is 1.076. The series resistance is 0.609 Ω. The centre wavelength shifts to a longer wavelength with the increasing temperature at a rate of 0.275288 nm/K.
基金supported by the National Natural Science Foundation of China (Grant Nos. 60577019 and 60777041)the International Cooperation Project of Shanxi Province,China (Grant No. 2007081019)
文摘This paper numerically demonstrates synchronization and bidirectional communication without delay line by using two semiconductor lasers with strong mutual injection in a face-to-face configuration. These results show that both of the two lasers＇ outputs synchronize with their input chaotic carriers. In addition, simulations demonstrate that this kind of synchronization can be used to realize bidirectional communications without delay line. Further studies indicate that within a small deviation in message amplitudes of two sides （±6%）, the message can be extracted with signal-noise-ratio more than 10 dB; and the signal-noise-ratio is extremely sensitive to the message rates mismatch of two sides, which may be used as a key of bidirectional communication.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61527823 and 61377105)
文摘Square microcavities, which support whispering-gallery modes with total internal reflections, can be employed as high-quality laser resonators for fabricating compact, low-threshold semiconductor lasers. In this paper, we review the recent progress of square microcavity semiconductor lasers. The characteristics of confined optical modes in the square microcavities are introduced briefly. Based on the mode properties of the square microcavities, dual-mode lasers with tunable wavelength intervals are realized for generating microwave signals. Furthermore, deformed square microcavity lasers with the sidewalls replaced by circular sides are proposed and experimentally demonstrated to enhance the mode confinement and increase the dual-mode interval to the THz range. In order to further reduce the device size, metal-confined wavelength-scale square cavity lasers are also demonstrated.
基金Project supported by the National Science and Technology Major Project of China(Grant Nos.2018YFB0504600and 2017YFB0405102)the Frontier Science Key Program of the President of the Chinese Academy of Sciences(Grant No.QYZDY-SSW-JSC006)+7 种基金the Pilot Project of the Chinese Academy of Sciences(Grant No.XDB43030302)the National Natural Science Foundation of China(Grant Nos.62090051,62090052,62090054,11874353,61935009,61934003,61904179,61727822,61805236,62004194,and 61991433)the Science and Technology Development Project of Jilin Province,China(Grant Nos.20200401062GX,202001069GX,20200501006GX,20200501007GX,20200501008GX,and 20190302042GX)the Key Research and Development Project of Guangdong Province,China(Grant No.2020B090922003)the Equipment Pre-researchChina(Grant No.2006ZYGG0304)the Special Scientific Research Project of the Academician Innovation Platform in Hainan Province,China(Grant No.YSPTZX202034)the Dawn Talent Training Program of CIOMP,China。
文摘The semiconductor laser array with single-mode emission is presented in this paper.The 6-μm-wide ridge waveguides(RWGs)are fabricated to select the lateral mode.Thus the fundamental mode of laser array can be obtained by the RWGs.And the maximum output power of single-mode emission can reach 36 W at an injection current of 43 A,after that,a kink will appear.The slow axis(SA)far-field divergence angle of the unit is 13.65.The beam quality factor M;of the units determined by the second-order moment(SOM)method,is 1.2.This single-mode emission laser array can be used for laser processing.
基金the National Natural Science Foundation of China(Grant No.62075168)Guang Dong Basic and Applied Basic Research Foundation(Grant No.2020A1515011088)Special Project in Key Fields of Guangdong Provincial Department of Education of China(Grant No.2020ZDZX3052 and 2019KZDZX1025)。
文摘We utilize three parallel reservoir computers using semiconductor lasers with optical feedback and light injection to model radar probe signals with delays.Three radar probe signals are generated by driving lasers constructed by a threeelement laser array with self-feedback.The response lasers are implemented also by a three-element lase array with both delay-time feedback and optical injection,which are utilized as nonlinear nodes to realize the reservoirs.We show that each delayed radar probe signal can be predicted well and to synchronize with its corresponding trained reservoir,even when parameter mismatches exist between the response laser array and the driving laser array.Based on this,the three synchronous probe signals are utilized for ranging to three targets,respectively,using Hilbert transform.It is demonstrated that the relative errors for ranging can be very small and less than 0.6%.Our findings show that optical reservoir computing provides an effective way for applications of target ranging.
