High power optically pumped vertical-external-cavity surface-emitting lasers with front and end pump are re- ported. The gain chip consists of 15 repeats of In0.26GaAs/GaAsP0.02 multiple quantum wells and 30 pairs of ...High power optically pumped vertical-external-cavity surface-emitting lasers with front and end pump are re- ported. The gain chip consists of 15 repeats of In0.26GaAs/GaAsP0.02 multiple quantum wells and 30 pairs of Alo.2GaAs/Alo.98GaAs distributed Bragg reflectors. The maximum output power of 3 W, optical-to-optical conversion efficiency of 22.4%, and slope efficiency of 29.8% are obtained with 5-℃ heatsink temperature under the front pump, while the maximum output power of 1.1 W, optical-to-optical conversion efficiency of 23.2%, and slope efficiency of 30.8% are reached with 5-℃ heatsink temperature under the end pump. Influences of thermal effects on the output power of the laser with front and end pump are discussed.展开更多
We demonstrate high-performance broadband tunable external-cavity lasers(ECLs) with the metal-organic chemical vapor deposition(MOCVD) grown In As/In P quantum dots(QDs) structures. Without cavity facet coatings, the ...We demonstrate high-performance broadband tunable external-cavity lasers(ECLs) with the metal-organic chemical vapor deposition(MOCVD) grown In As/In P quantum dots(QDs) structures. Without cavity facet coatings, the 3-d B spectral bandwidth of the Fabry–Perot(FP) laser is approximately 10.8 nm, while the tuning bandwidth of ECLs is 45 nm.Combined with the anti-reflection(AR)/high-reflection(HR) facet coating, a 92 nm bandwidth tuning range has been obtained with the wavelength covering from 1414 nm to 1506 nm. In most of the tuning range, the threshold current density is lower than 1.5 k A/cm2. The maximum output power of 6.5 m W was achieved under a 500 m A injection current.All achievements mentioned above were obtained under continuous-wave(CW) mode at room temperature(RT).展开更多
External-cavity birefringence feedback effects of the microchip Nd：YAG laser are presented. When a birefringence element is placed in the external feedback cavity of the laser, two orthogonally polarized laser beams ...External-cavity birefringence feedback effects of the microchip Nd：YAG laser are presented. When a birefringence element is placed in the external feedback cavity of the laser, two orthogonally polarized laser beams with a phase difference are output. The phase difference is twice as large as the phase retardation in the external cavity along the two orthogonal directions. The variable extra-cavity birefringence, caused by rotation of the external-cavity birefringenee element, results in tunable phase difference between the two orthogonally polarized beams. This means that the roll angle information has been translated to phase difference of two output laser beams. A theoretical analysis based on the Fabry-Perot cavity equivalent model and refractive index ellipsoid is presented, which is in good agreement with the experimental results. This phenomenon has potential applications for roll angle measurement.展开更多
We report an external cavity quantum cascade laser （EC-QCL） operating near 6.9μm using the Littman Metcalf configuration. The EC-QCL works in a pulsed mode and can be tuned continuously from 1340 to 1640cm^-1 by on...We report an external cavity quantum cascade laser （EC-QCL） operating near 6.9μm using the Littman Metcalf configuration. The EC-QCL works in a pulsed mode and can be tuned continuously from 1340 to 1640cm^-1 by only tilting the tuning mirror. The fine tuning ability of the EC-QCL is demonstrated by measuring the absorption spectrum of water in the ambient air with a lock-in amplifier.展开更多
We presented 980-nm oxide-confined vertical-cavity surface-emitting lasers （VCSELs） with a 16 -um oxide aperture. Optical power, voltage, and emission wavelength are measured in an ambient temperature range of 5 ℃-...We presented 980-nm oxide-confined vertical-cavity surface-emitting lasers （VCSELs） with a 16 -um oxide aperture. Optical power, voltage, and emission wavelength are measured in an ambient temperature range of 5 ℃-80 ℃. Measurements combined with an empirical model are used to analyse the power dissipation in the device and the physical mechanism contributing to the thermal rollover phenomenon in VCSEL. It is found that the carrier leakage induced selfheating in the active region and the Joule heating caused by the series resistance are the main sources of power dissipation. In addition, carrier leakage induced self-heating increases as the injection current increases, resulting in a rapid decrease of the internal quantum efficiency, which is a dominant contribution to the thermal rollover of the VCSEL at a larger current. Our study provides useful guidelines to design a 980-nm oxide-confined VCSEL for thermal performance enhancement.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
We report the study on a short wavelength-tunable vertical-cavity surface-emitting laser utilizing a monolithically integrated bridge tuning microelectromechanical system. A deformable-bridge top mirror suspended abov...We report the study on a short wavelength-tunable vertical-cavity surface-emitting laser utilizing a monolithically integrated bridge tuning microelectromechanical system. A deformable-bridge top mirror suspended above an active region is utilized. Applied bridge-substrate bias produces an electrostatic force which reduces the spacing of air-gap and tunes the resonant wavelength toward a shorter wavelength （blue-shift）, Good laser characteristics are obtained： such as continuous tuning ranges over 11 nm near 940 nm for 0-9 V tuning bias, the peak output power near 1 mW and the full-width-half-maximum limited to approximately 3.2-6.8 rim. A detailed simulation of the micromechanical and optical characteristics of these devices is performed, and the ratio of bridge displacement to wavelength shift has been found to be 3：1.展开更多
The mode splitting induced by electro-optic birefringence in a P-I-N InGaAs/GaAs/A1GaAs vertical-cavity surface- emitting laser （VCSEL） has been studied by polarized electroluminescence （EL） at room temperature. T...The mode splitting induced by electro-optic birefringence in a P-I-N InGaAs/GaAs/A1GaAs vertical-cavity surface- emitting laser （VCSEL） has been studied by polarized electroluminescence （EL） at room temperature. The polarized EL spectra with E｜｜[110] and E ｜｜ [150] directions, are extracted for different injected currents. The mode splitting of the two orthogonal polarized modes for a VCSEL device is determined, and its value increases linearly with the increasing injected current due to electro-optic birefringence; This article demonstrates that the polarized EL is a powerful tool to study the mode splitting and polarization anisotropy of a VCSEL device.展开更多
Polarization-stable 980 nm oxide-confined vertical-cavity surface-emitting lasers with 3 μm diamond-shaped aper- ture are fabricated by comprehensively utilizing the anisotropic properties of wet etching and wet nitr...Polarization-stable 980 nm oxide-confined vertical-cavity surface-emitting lasers with 3 μm diamond-shaped aper- ture are fabricated by comprehensively utilizing the anisotropic properties of wet etching and wet nitrogen oxida- tion of Ⅲ-Ⅴ semiconductor materials. Polarization-stable operation along the major axis of the diamond-shaped oxide aperture with 11 dB orthogonal polarization suppression ratio is achieved in a temperature range of 15-55℃ from the threshold to 4 mA.展开更多
A low-threshold and high-power oxide-confined 850-nm AlInGaAs strained quantum-well （QW） vertical-cavity surface-emitting laser （VCSEL） based on an intra-cavity contacted structure is fabricated. A threshold curre...A low-threshold and high-power oxide-confined 850-nm AlInGaAs strained quantum-well （QW） vertical-cavity surface-emitting laser （VCSEL） based on an intra-cavity contacted structure is fabricated. A threshold current of 1.5 mA for a 22 μm oxide aperture device is achieved, which corresponds to a threshold current density of 0.395 kA/cm2. The peak output optical power reaches 17.5 mW at an injection current of 30 mA at room temperature under pulsed opera- tion. While under continuous-wave （CW） operation, the maximum power attains 10.5 mW. Such a device demonstrates a high characteristic temperature of 327 K within a temperature range from -12°C to 96 °C and good reliability under a lifetime test. There is almost no decrease of the optical power when the device operates at a current of 5 mA at room temperature under the CW injection current.展开更多
The output performance of a 980-nm broad-area vertical-cavity surface-emitting laser （VCSEL） is improved by optimizing the p-electrode diameter in this study. Based on a three-dimensional finite-element method, the ...The output performance of a 980-nm broad-area vertical-cavity surface-emitting laser （VCSEL） is improved by optimizing the p-electrode diameter in this study. Based on a three-dimensional finite-element method, the current density distribution within the active region of the VCSEL is optimized through the appropriate adjustment of the p-electrode diameter, and uniform current-density distribution is achieved. Then, the effects of this optimization are studied experimentally. The L-I-V characteristics under different temperatures of the VCSELs with different p-electrode diameters are investigated, and better temperature stability is demonstrated in the VCSEL with an optimized p-electrode diameter. The far-field measurements show that with an injected current of 2 A, the far-field divergence angle of the VCSEL with an optimized p-electrode diameter is 9°, which is much lower than the far-field angle of the VCSEL without this optimization. Also the VCSEL with an optimized p-electrode diameter shows a better near-field distribution.展开更多
By using an external-cavity frequency-doubling master oscillator fiber power amplifier （MOPA）, a 700 mW continuous-wave single-frequency laser source at 780 nm is produced. It is shown that the frequency doubling ef...By using an external-cavity frequency-doubling master oscillator fiber power amplifier （MOPA）, a 700 mW continuous-wave single-frequency laser source at 780 nm is produced. It is shown that the frequency doubling efficiency is improved when the seed diode laser is optically locked to a resonant frequency of a confocal Fabry-Perot （F-P） cavity. This phenomenon can be attributed to the narrowing of the 1.56 μm laser linewidth and explained by our presented theoretical model. The experimental results are found to be in good agreement with the theoretical predictions.展开更多
The 850-nm oxide-confined vertical-cavity surface-emitting lasers with petal-shape holey structures are presented. An area-weighted average refractive index model is given to analyse their effective index profiles, an...The 850-nm oxide-confined vertical-cavity surface-emitting lasers with petal-shape holey structures are presented. An area-weighted average refractive index model is given to analyse their effective index profiles, and the graded index distribution in the holey region is demonstrated. The index step between the optical aperture and the holey region is obtained which is related merely to the etching depth. Four types of holey vertical-cavity surface-emitting lasers with different parameters are fabricated as well as the conventional oxide-confined vertical-cavity surface-emitting laser. Compared with the conventional oxide-confined vertical-cavity surface-emitting laser without etched holes, the holey vertical-cavity surface-emitting laser possesses an improved beam quality due to its graded index distribution, but has a lower output power, higher threshold current and lower slope efficiency. With the hole number increased, the holey vertical-cavity surface-emitting laser can realize the single-mode operation throughout the entire current range, and reduces the beam divergence further. The loss mechanism is used to explain the single-mode characteristic, and the reduced beam divergence is attributed to the shallow etching. High coupling efficiency of 86% to a multi-mode fibre is achieved for the single-mode device in the experiment.展开更多
The effect of mesa size on th e thermal characteristics of etched mesa vertical-cavity surface-emitting lase rs(VCSELs) is studied. The numerical results show that the mesa size of the top mirror strongly influences t...The effect of mesa size on th e thermal characteristics of etched mesa vertical-cavity surface-emitting lase rs(VCSELs) is studied. The numerical results show that the mesa size of the top mirror strongly influences the temperature distribution inside the etched mesa V CSEL. Under a certain driving voltage, with decreasing mesa size, the location o f the maximal temperature moves towards the p-contact metal, the temperature in the core region of the active layer rises greatly, and the thermal characterist ics of the etched mesa VCSELs will deteriorate.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
Taking into account oxidation temperature, N2 carrier gas flow, and the geometry of the mesa structures this paper investigates the characteristics of selective oxidation during the fabrication of the vertical cavity ...Taking into account oxidation temperature, N2 carrier gas flow, and the geometry of the mesa structures this paper investigates the characteristics of selective oxidation during the fabrication of the vertical cavity surface emitting laser （VCSEL） in detail. Results show that the selective oxidation follows a law which differs from any reported in the literature. Below 435℃ selective oxidation of Al0.98Ga0.02As follows a linear growth law for the two mesa structures employed in VCSEL. Above 435℃ approximately increasing parabolic growth is found, which is influenced by the geometry of the mesa structures. Theoretical analysis on the difference between the two structures for the initial oxidation has been performed, which demonstrates that the geometry of the mesa structures does influence on the growth rate of oxide at higher temperatures.展开更多
The intrinsic features involving a circularly symmetric beam profile with low divergence, planar geometry as well as the increasingly enhanced power of vertical-cavity surface-emitting lasers （VCSELs） have made the ...The intrinsic features involving a circularly symmetric beam profile with low divergence, planar geometry as well as the increasingly enhanced power of vertical-cavity surface-emitting lasers （VCSELs） have made the VCSEL a promising pump source in direct end bonding to a solid-state laser medium to form the minimized, on-wafer integrated laser system. This scheme will generate a surface contact pump configuration and thus additional end thermal coupling to the laser medium through the joint interface of both materials, apart from pump beam heating. This paper analytically models temperature distributions in both VCSEL and the laser medium from the end thermal coupling regarding surface contact pump configuration using a top-emitting VCSEL as the pump source for the first time. The analytical solutions are derived by introducing relative temperature and mean temperature expressions. The results show that the end contact heating by the VCSEL could lead to considerable temperature variations associated with thermal phase shift and thermal lensing in the laser medium. However, if the central temperature of the interface is increased by less than 20 K, the end contact heating does not have a significant thermal influence on the laser medium. In this case, the thermal effect should be dominated by pump beam heating. This work provides useful analytical results for further analysis of hybrid thermal effects on those lasers pumped by a direct VCSEL bond.展开更多
Polarization self-modulation effect in a free oscillated Nd：YAG laser is investigated after a quarter wave plate is introduced independently in the two positions of the cavity. As described in the previous experiment...Polarization self-modulation effect in a free oscillated Nd：YAG laser is investigated after a quarter wave plate is introduced independently in the two positions of the cavity. As described in the previous experiments, the intensity components in the orthogonal directions are modulated with a period of the round-trip time or twice. Different pulse shapes reveal that the seed field from the spontaneous emission is not uniform and seems to be stochastic for each pulse.展开更多
The wavelength tuning ranges of a grating external-cavity laser diode (ECLD) have been studied by the equivalent cavity method. The maximum tuning range (MTR) and the continuous tuning range (CTR), which are related t...The wavelength tuning ranges of a grating external-cavity laser diode (ECLD) have been studied by the equivalent cavity method. The maximum tuning range (MTR) and the continuous tuning range (CTR), which are related to the maximum and the minimum threshold carrier densities, are deduced from the threshold condition. We define a ratio of the CTR to the MTR. This ratio is only determined by the reflectivities of the external and internal facets of the ECLD. The analysis shows that there is an appropriate combination of the external and internal-cavity reflectivities to obtain a given CTR in the design of an ECLD.展开更多
Semiconductor vertical-cavity surface-emitting lasers(VCSELs)with wavelengths from 491.8 to 565.7 nm,covering most of the‘green gap’,are demonstrated.For these lasers,the same quantum dot(QD)active region was used,w...Semiconductor vertical-cavity surface-emitting lasers(VCSELs)with wavelengths from 491.8 to 565.7 nm,covering most of the‘green gap’,are demonstrated.For these lasers,the same quantum dot(QD)active region was used,whereas the wavelength was controlled by adjusting the cavity length,which is difficult for edge-emitting lasers.Compared with reports in the literature for green VCSELs,our lasers have set a few world records for the lowest threshold,longest wavelength and continuous-wave(CW)lasing at room temperature.The nanoscale QDs contribute dominantly to the low threshold.The emitting wavelength depends on the electron–photon interaction or the coupling between the active layer and the optical field,which is modulated by the cavity length.The green VCSELs exhibit a low-thermal resistance of 915 kW^(−1),which benefits the CW lasing.Such VCSELs are important for small-size,low power consumption full-color displays and projectors.展开更多
基金Project supported by the Chongqing Research Program of Basic Research and Frontier Technology(Grant No.cstc2015jcyj BX0098)the National Natural Science Foundation of China(Grant No.61575011)the Foundation for the Creative Research Groups of Higher Education of Chongqing(Grant No.CXTDX201601016)
文摘High power optically pumped vertical-external-cavity surface-emitting lasers with front and end pump are re- ported. The gain chip consists of 15 repeats of In0.26GaAs/GaAsP0.02 multiple quantum wells and 30 pairs of Alo.2GaAs/Alo.98GaAs distributed Bragg reflectors. The maximum output power of 3 W, optical-to-optical conversion efficiency of 22.4%, and slope efficiency of 29.8% are obtained with 5-℃ heatsink temperature under the front pump, while the maximum output power of 1.1 W, optical-to-optical conversion efficiency of 23.2%, and slope efficiency of 30.8% are reached with 5-℃ heatsink temperature under the end pump. Influences of thermal effects on the output power of the laser with front and end pump are discussed.
基金Project supported by the National Natural Science Foundation of China(Grant No.61974141)Tianjin Municipal Science and Technology BureauScience and Technology Innovation Bureau of China-Singapore Tianjin Eco-City。
文摘We demonstrate high-performance broadband tunable external-cavity lasers(ECLs) with the metal-organic chemical vapor deposition(MOCVD) grown In As/In P quantum dots(QDs) structures. Without cavity facet coatings, the 3-d B spectral bandwidth of the Fabry–Perot(FP) laser is approximately 10.8 nm, while the tuning bandwidth of ECLs is 45 nm.Combined with the anti-reflection(AR)/high-reflection(HR) facet coating, a 92 nm bandwidth tuning range has been obtained with the wavelength covering from 1414 nm to 1506 nm. In most of the tuning range, the threshold current density is lower than 1.5 k A/cm2. The maximum output power of 6.5 m W was achieved under a 500 m A injection current.All achievements mentioned above were obtained under continuous-wave(CW) mode at room temperature(RT).
基金supported by the National Natural Science Foundation of China (Grant No 50575110)
文摘External-cavity birefringence feedback effects of the microchip Nd：YAG laser are presented. When a birefringence element is placed in the external feedback cavity of the laser, two orthogonally polarized laser beams with a phase difference are output. The phase difference is twice as large as the phase retardation in the external cavity along the two orthogonal directions. The variable extra-cavity birefringence, caused by rotation of the external-cavity birefringenee element, results in tunable phase difference between the two orthogonally polarized beams. This means that the roll angle information has been translated to phase difference of two output laser beams. A theoretical analysis based on the Fabry-Perot cavity equivalent model and refractive index ellipsoid is presented, which is in good agreement with the experimental results. This phenomenon has potential applications for roll angle measurement.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11174098 and 11574107the SelfDetermined Research Funds of Central China Normal University under Grant No CCNU15A02034
文摘We report an external cavity quantum cascade laser （EC-QCL） operating near 6.9μm using the Littman Metcalf configuration. The EC-QCL works in a pulsed mode and can be tuned continuously from 1340 to 1640cm^-1 by only tilting the tuning mirror. The fine tuning ability of the EC-QCL is demonstrated by measuring the absorption spectrum of water in the ambient air with a lock-in amplifier.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60908012 and 61076148)the Foundation of Beijing Municipal Education Commission, China (Grant No. KM201010005030)
文摘We presented 980-nm oxide-confined vertical-cavity surface-emitting lasers （VCSELs） with a 16 -um oxide aperture. Optical power, voltage, and emission wavelength are measured in an ambient temperature range of 5 ℃-80 ℃. Measurements combined with an empirical model are used to analyse the power dissipation in the device and the physical mechanism contributing to the thermal rollover phenomenon in VCSEL. It is found that the carrier leakage induced selfheating in the active region and the Joule heating caused by the series resistance are the main sources of power dissipation. In addition, carrier leakage induced self-heating increases as the injection current increases, resulting in a rapid decrease of the internal quantum efficiency, which is a dominant contribution to the thermal rollover of the VCSEL at a larger current. Our study provides useful guidelines to design a 980-nm oxide-confined VCSEL for thermal performance enhancement.
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Project supported by the National Natural Science Foundation of China （Grant No 60506012）, the Fok Ying-Tong Foundation （Grant No 101062）, the Natural Science Foundation of Beijing China （Grant No KZ200510005003）, the Science Star of Beijing China （Grant No 2005A11）, and the Funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality China （Grant No 20051D0501502）.Acknowledgement The authors gratefully acknowledge the staff of M0CVD, Zhou Deshu, and Han Jinru for technical assistance. The authors also thank Professor Academician Chen Lianghui, Professor Tan Manqing and Mr Wang Xuming at the Institute of Semiconductors, CAS for technological support in device fabrication.
文摘We report the study on a short wavelength-tunable vertical-cavity surface-emitting laser utilizing a monolithically integrated bridge tuning microelectromechanical system. A deformable-bridge top mirror suspended above an active region is utilized. Applied bridge-substrate bias produces an electrostatic force which reduces the spacing of air-gap and tunes the resonant wavelength toward a shorter wavelength （blue-shift）, Good laser characteristics are obtained： such as continuous tuning ranges over 11 nm near 940 nm for 0-9 V tuning bias, the peak output power near 1 mW and the full-width-half-maximum limited to approximately 3.2-6.8 rim. A detailed simulation of the micromechanical and optical characteristics of these devices is performed, and the ratio of bridge displacement to wavelength shift has been found to be 3：1.
基金Project supported the National Key Basic Research and Development Program of China (Grant Nos.2012CB921304 and 2013CB632805)the National Natural Science Foundation of China (Grant Nos.60990313,61306120,and 6106003)the Foundation of Fuzhou University (Grant No.022498)
文摘The mode splitting induced by electro-optic birefringence in a P-I-N InGaAs/GaAs/A1GaAs vertical-cavity surface- emitting laser （VCSEL） has been studied by polarized electroluminescence （EL） at room temperature. The polarized EL spectra with E｜｜[110] and E ｜｜ [150] directions, are extracted for different injected currents. The mode splitting of the two orthogonal polarized modes for a VCSEL device is determined, and its value increases linearly with the increasing injected current due to electro-optic birefringence; This article demonstrates that the polarized EL is a powerful tool to study the mode splitting and polarization anisotropy of a VCSEL device.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61222501 and 61335004the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No 20111103110019
文摘Polarization-stable 980 nm oxide-confined vertical-cavity surface-emitting lasers with 3 μm diamond-shaped aper- ture are fabricated by comprehensively utilizing the anisotropic properties of wet etching and wet nitrogen oxida- tion of Ⅲ-Ⅴ semiconductor materials. Polarization-stable operation along the major axis of the diamond-shaped oxide aperture with 11 dB orthogonal polarization suppression ratio is achieved in a temperature range of 15-55℃ from the threshold to 4 mA.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.60908012 and 61076148)the Foundation of Beijing Municipal Education Commission,China (Grant No.KM201010005030)
文摘A low-threshold and high-power oxide-confined 850-nm AlInGaAs strained quantum-well （QW） vertical-cavity surface-emitting laser （VCSEL） based on an intra-cavity contacted structure is fabricated. A threshold current of 1.5 mA for a 22 μm oxide aperture device is achieved, which corresponds to a threshold current density of 0.395 kA/cm2. The peak output optical power reaches 17.5 mW at an injection current of 30 mA at room temperature under pulsed opera- tion. While under continuous-wave （CW） operation, the maximum power attains 10.5 mW. Such a device demonstrates a high characteristic temperature of 327 K within a temperature range from -12°C to 96 °C and good reliability under a lifetime test. There is almost no decrease of the optical power when the device operates at a current of 5 mA at room temperature under the CW injection current.
基金supported by the National Natural Science Foundation of China (Grant Nos. 61204056,61234004,90923037,and 11074247)the Jilin ProvincialScience and Technology Development Plan Item (Grant Nos. 201105025 and 20116011)
文摘The output performance of a 980-nm broad-area vertical-cavity surface-emitting laser （VCSEL） is improved by optimizing the p-electrode diameter in this study. Based on a three-dimensional finite-element method, the current density distribution within the active region of the VCSEL is optimized through the appropriate adjustment of the p-electrode diameter, and uniform current-density distribution is achieved. Then, the effects of this optimization are studied experimentally. The L-I-V characteristics under different temperatures of the VCSELs with different p-electrode diameters are investigated, and better temperature stability is demonstrated in the VCSEL with an optimized p-electrode diameter. The far-field measurements show that with an injected current of 2 A, the far-field divergence angle of the VCSEL with an optimized p-electrode diameter is 9°, which is much lower than the far-field angle of the VCSEL without this optimization. Also the VCSEL with an optimized p-electrode diameter shows a better near-field distribution.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 60527003,60608011 and 60878003)the State Key Program for Basic Research of China (Grant No 2007CB316501)
文摘By using an external-cavity frequency-doubling master oscillator fiber power amplifier （MOPA）, a 700 mW continuous-wave single-frequency laser source at 780 nm is produced. It is shown that the frequency doubling efficiency is improved when the seed diode laser is optically locked to a resonant frequency of a confocal Fabry-Perot （F-P） cavity. This phenomenon can be attributed to the narrowing of the 1.56 μm laser linewidth and explained by our presented theoretical model. The experimental results are found to be in good agreement with the theoretical predictions.
基金supported by the National Key Basic Research Special Foundation of China (Grant No. 2011CB922000)the National Natural Science Foundation of China (Grant Nos. 61025025 and 60838003)the National High Technology Research and Development Program of China (Grant Nos. 2007AA03Z410 and 2007AA03Z408)
文摘The 850-nm oxide-confined vertical-cavity surface-emitting lasers with petal-shape holey structures are presented. An area-weighted average refractive index model is given to analyse their effective index profiles, and the graded index distribution in the holey region is demonstrated. The index step between the optical aperture and the holey region is obtained which is related merely to the etching depth. Four types of holey vertical-cavity surface-emitting lasers with different parameters are fabricated as well as the conventional oxide-confined vertical-cavity surface-emitting laser. Compared with the conventional oxide-confined vertical-cavity surface-emitting laser without etched holes, the holey vertical-cavity surface-emitting laser possesses an improved beam quality due to its graded index distribution, but has a lower output power, higher threshold current and lower slope efficiency. With the hole number increased, the holey vertical-cavity surface-emitting laser can realize the single-mode operation throughout the entire current range, and reduces the beam divergence further. The loss mechanism is used to explain the single-mode characteristic, and the reduced beam divergence is attributed to the shallow etching. High coupling efficiency of 86% to a multi-mode fibre is achieved for the single-mode device in the experiment.
基金National High Technology Research and Development Programof China(2001AA312180)
文摘The effect of mesa size on th e thermal characteristics of etched mesa vertical-cavity surface-emitting lase rs(VCSELs) is studied. The numerical results show that the mesa size of the top mirror strongly influences the temperature distribution inside the etched mesa V CSEL. Under a certain driving voltage, with decreasing mesa size, the location o f the maximal temperature moves towards the p-contact metal, the temperature in the core region of the active layer rises greatly, and the thermal characterist ics of the etched mesa VCSELs will deteriorate.
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Taking into account oxidation temperature, N2 carrier gas flow, and the geometry of the mesa structures this paper investigates the characteristics of selective oxidation during the fabrication of the vertical cavity surface emitting laser （VCSEL） in detail. Results show that the selective oxidation follows a law which differs from any reported in the literature. Below 435℃ selective oxidation of Al0.98Ga0.02As follows a linear growth law for the two mesa structures employed in VCSEL. Above 435℃ approximately increasing parabolic growth is found, which is influenced by the geometry of the mesa structures. Theoretical analysis on the difference between the two structures for the initial oxidation has been performed, which demonstrates that the geometry of the mesa structures does influence on the growth rate of oxide at higher temperatures.
文摘The intrinsic features involving a circularly symmetric beam profile with low divergence, planar geometry as well as the increasingly enhanced power of vertical-cavity surface-emitting lasers （VCSELs） have made the VCSEL a promising pump source in direct end bonding to a solid-state laser medium to form the minimized, on-wafer integrated laser system. This scheme will generate a surface contact pump configuration and thus additional end thermal coupling to the laser medium through the joint interface of both materials, apart from pump beam heating. This paper analytically models temperature distributions in both VCSEL and the laser medium from the end thermal coupling regarding surface contact pump configuration using a top-emitting VCSEL as the pump source for the first time. The analytical solutions are derived by introducing relative temperature and mean temperature expressions. The results show that the end contact heating by the VCSEL could lead to considerable temperature variations associated with thermal phase shift and thermal lensing in the laser medium. However, if the central temperature of the interface is increased by less than 20 K, the end contact heating does not have a significant thermal influence on the laser medium. In this case, the thermal effect should be dominated by pump beam heating. This work provides useful analytical results for further analysis of hybrid thermal effects on those lasers pumped by a direct VCSEL bond.
基金Supported by the National Natural Science Foundation of China under Grant No 10472123, and the Innovation Project ofChinese Academy of Sciences.
文摘Polarization self-modulation effect in a free oscillated Nd：YAG laser is investigated after a quarter wave plate is introduced independently in the two positions of the cavity. As described in the previous experiments, the intensity components in the orthogonal directions are modulated with a period of the round-trip time or twice. Different pulse shapes reveal that the seed field from the spontaneous emission is not uniform and seems to be stochastic for each pulse.
基金The Foundation of National Railways Ministry , National Studying
文摘The wavelength tuning ranges of a grating external-cavity laser diode (ECLD) have been studied by the equivalent cavity method. The maximum tuning range (MTR) and the continuous tuning range (CTR), which are related to the maximum and the minimum threshold carrier densities, are deduced from the threshold condition. We define a ratio of the CTR to the MTR. This ratio is only determined by the reflectivities of the external and internal facets of the ECLD. The analysis shows that there is an appropriate combination of the external and internal-cavity reflectivities to obtain a given CTR in the design of an ECLD.
基金supported by the National Natural Science Foundation of China(Grant Nos.61274052,11474235,U1505253)the Major Scientific and Technological Special Project of Guangdong Province(No.2014B010119004)the Science Challenge Project(No.JCKY2016212A503).
文摘Semiconductor vertical-cavity surface-emitting lasers(VCSELs)with wavelengths from 491.8 to 565.7 nm,covering most of the‘green gap’,are demonstrated.For these lasers,the same quantum dot(QD)active region was used,whereas the wavelength was controlled by adjusting the cavity length,which is difficult for edge-emitting lasers.Compared with reports in the literature for green VCSELs,our lasers have set a few world records for the lowest threshold,longest wavelength and continuous-wave(CW)lasing at room temperature.The nanoscale QDs contribute dominantly to the low threshold.The emitting wavelength depends on the electron–photon interaction or the coupling between the active layer and the optical field,which is modulated by the cavity length.The green VCSELs exhibit a low-thermal resistance of 915 kW^(−1),which benefits the CW lasing.Such VCSELs are important for small-size,low power consumption full-color displays and projectors.
