Modulation bandwidth enhancement in a directly modulated two-section distributed feedback(TS-DFB)laser based on a detuned loading effect is investigated and experimentally demonstrated.The results show that the 3-dB b...Modulation bandwidth enhancement in a directly modulated two-section distributed feedback(TS-DFB)laser based on a detuned loading effect is investigated and experimentally demonstrated.The results show that the 3-dB bandwidth of the TS-DFB laser is increased to 17.6 GHz and that chirp parameter can be reduced to 2.24.Compared to the absence of a detuned loading effect,there is a 4.6 GHz increase and a 2.45 reduction,respectively.After transmitting a 10 Gb/s non-return-to-zero(NRZ)signal through a 5-km fiber,the modulation eye diagram still achieves a large opening.Eight-channel laser arrays with precise wavelength spacing are fabricated.Each TS-DFB laser in the array has side mode suppression ratios(SMSR)>49.093 dB and the maximum wavelength residual<0.316 nm.展开更多
In this work,a hybrid integrated optical transmitter module was designed and fabricated.A proton-exchanged Mach–Zehnder lithium niobate(LiNbO_(3))modulator chip was chosen to enhance the output extinction ratio.A fib...In this work,a hybrid integrated optical transmitter module was designed and fabricated.A proton-exchanged Mach–Zehnder lithium niobate(LiNbO_(3))modulator chip was chosen to enhance the output extinction ratio.A fiber was used to adjust the rotation of the polarization direction caused by the optical isolator.The whole optical path structure,including the laser chip,lens,fiber,and modulator chip,was simulated to achieve high optical output efficiency.After a series of process improvements,a module with an output extinction ratio of 34 dB and a bandwidth of 20.5 GHz(from 2 GHz)was obtained.The optical output efficiency of the whole module reached approximately 21%.The link performance of the module was also measured.展开更多
We experimentally demonstrate an In P-based hybrid integration of a single-mode DFB laser emitting at around 1310 nm and a tunneling diode. The evident negative differential resistance regions are obtained in both ele...We experimentally demonstrate an In P-based hybrid integration of a single-mode DFB laser emitting at around 1310 nm and a tunneling diode. The evident negative differential resistance regions are obtained in both electrical and optical output characteristics. The electrical and optical bistabilities controlled by the voltage through the tunneling diode are also measured. When the voltage changes between 1.46 V and 1.66 V, a 200-mV-wide hysteresis loop and an optical power ON/OFF ratio of 17 dB are obtained. A side-mode suppression ratio of the integrated device in the ON state is up to 43 dB. The tunneling diode can switch on/off the laser within a very small voltage range compared with that directly controlled by a voltage source.展开更多
A new all-optical flip-flop based on a nonlinear Distributed feedback (DFB) structure is proposed. The device does not require a holding beam. A nonlinear part of the grating is detuned from the remaining part of the ...A new all-optical flip-flop based on a nonlinear Distributed feedback (DFB) structure is proposed. The device does not require a holding beam. A nonlinear part of the grating is detuned from the remaining part of the grating and has negative nonlinear coefficient. Optical gain is provided by an injected electrical current into an active layer. In the OFF state, due to the detuned section, no laser light is generated in the device. An injected optical pulse reduces the detuning of the nonlinear section, and the optical feedback provided by the DFB structure generates a laser light in the structure that sustains the change in the detuned section. The device is switched “OFF” by detuning another section of the grating by a Reset pulse. The Reset pulse reduces the refractive index of that section by the generation of electron-hole pairs. The Reset pulse wavelength is adjusted such that the optical gain provided by the active layer at that wavelength is zero. The Reset pulse is prevented from reaching the nonlinear detuned section by introducing an optical absorber in the laser cavity to attenuate the pulse. The device is simulated in time domain using General Purpose Graphics Processing Unit (GPGPU) computing. Set-Reset operations are in nanosecond time scale.展开更多
In this paper,the fabrication of 1.3μm InGaAsP/InP gain-coupled DFB lasers with lossgrating is reported for the first time.A technique of regrowth on corrugated surface usingLPE is developed.By using GaAs as the cove...In this paper,the fabrication of 1.3μm InGaAsP/InP gain-coupled DFB lasers with lossgrating is reported for the first time.A technique of regrowth on corrugated surface usingLPE is developed.By using GaAs as the cover of thermal protection and controlling theamount of the super cooling,high quality epitxial layers on corrugated surface are obtained.The oxide stripe lasers with a stripe width of 20μm are fabricated.Single-mode oscillation isachieved at 1.293μm,and a high single-mode oscillation yield is also obtained.展开更多
The stable long-distance transmission of radio-frequency(RF)signals holds significant importance from various aspects,including the comparison of optical frequency standards,remote monitoring and control,scientific re...The stable long-distance transmission of radio-frequency(RF)signals holds significant importance from various aspects,including the comparison of optical frequency standards,remote monitoring and control,scientific research and experiments,and RF spectrum management.We demonstrate a scheme where an ultrastable frequency signal was transmitted over a 50 km coiled fiber.The optical RF signal is generated using a two-section distributed feedback(DFB)laser for direct modulation based on the reconstruction equivalent chirp(REC)technique.The 3-dB modulation bandwidth of the two-section DFB laser is 18 GHz and the residual phase noise of-122.87 dBc/Hz is achieved at 10-Hz offset frequency.We report a short-term stability of 1.62×10^(-14)at an average time of 1 s and a long-term stability of 6.55×10^(-18)at the measurement time of 62,000 s when applying current to the front section of the DFB laser.By applying power to both sections,the stability of the system improves to 4.42×10^(-18)within a testing period of 56,737 s.Despite applying temperature variations to the transmission link,long-term stability of 8.63×10^(-18)at 23.9 h can still be achieved.展开更多
We demonstrate a high-resolution frequency-modulated continuous-wave dual-frequency LIDAR system based on a monolithic integrated two-section(TS) distributed feedback(DFB) laser. In order to achieve phase locking of t...We demonstrate a high-resolution frequency-modulated continuous-wave dual-frequency LIDAR system based on a monolithic integrated two-section(TS) distributed feedback(DFB) laser. In order to achieve phase locking of the two lasers in the TS-DFB laser, the sideband optical injection locking technique is employed. A high-quality linear frequency-modulated signal is achieved from the TS-DFB laser. Utilizing the proposed LIDAR system, the distance and velocity of a target can be measured accurately. The maximum relative errors of distance and velocity measurement are 1.6% and 3.18%, respectively.展开更多
A more than 12 mW highly efficient fibre-DFB laser operating at 1618.3 nm is fabricated and characterised. Its high-power, low-noise and single-polarisation characteristics make it very suitable WDM-source for L-band ...A more than 12 mW highly efficient fibre-DFB laser operating at 1618.3 nm is fabricated and characterised. Its high-power, low-noise and single-polarisation characteristics make it very suitable WDM-source for L-band transmission.展开更多
A novel cascaded DFB laser,which consists of two serial gratings to provide selectable wavelengths,is presented and analyzed by the transfer matrix method.In this method,efficient facet reflectivity is derived from th...A novel cascaded DFB laser,which consists of two serial gratings to provide selectable wavelengths,is presented and analyzed by the transfer matrix method.In this method,efficient facet reflectivity is derived from the transfer matrix built for each serial section and is then used to simulate the performance of the novel cascaded DFB laser through self-consistently solving the gain equation,the coupled wave equation and the current continuity equations.The simulations prove the feasibility of this kind of wavelength selectable laser and a corresponding designed device with two selectable wavelengths of 1.51μm and 1.53μm is realized by experiments on InP-based multiple quantum well structure.展开更多
EAM-DFB monolithic light sources with the coupling waveguide between laser and modulator have been developed. 10mw output light power at 90mA and 18dB extinction ratio at -2V has been achieved.
A novel distribute feedback (DFB) laser which gave two different wavelengths under two distinct work conditions was fabricated. The laser consists of two Bragg gratings with different periods corresponding to waveleng...A novel distribute feedback (DFB) laser which gave two different wavelengths under two distinct work conditions was fabricated. The laser consists of two Bragg gratings with different periods corresponding to wavelength spacing of 20 nm in an identical active area. When driving current was injected into one of the different sections separately, two different wavelengths at 1542.4 and 1562.5 nm were realized. The side mode suppression ratio (SMSR) of 45 dB or more both for the two Bragg wavelengths were achieved. The fabricating process of the laser was just the samp as that of traditional DFB laser diode. This device can be potentially used in coarse wavelength division multiplexer (CWDM) as a promising light source and the technology idea can be used to enlarge the transmission capacity in metro area network (MAN).展开更多
We propose, design, and realize a compact stabilized laser system that can be tuned within 24 GHz automatically. This laser system consists of two distributed feedback （DFB） lasers, one of which is reference and loc...We propose, design, and realize a compact stabilized laser system that can be tuned within 24 GHz automatically. This laser system consists of two distributed feedback （DFB） lasers, one of which is reference and locked to the D2 line of Rb87, the other laser is a slave that is locked to the reference laser via a loop servo. We measured the frequency of the beating signal of the two lasers and generated an error signal, which controlled the frequency of the slave laser to close the loop. We compressed the fluctuation of the beating signal’s frequency to less than 1 MHz. Furthermore, the system can also automatically determine and control whether the slave is red detuned or blue detuned to the reference. The dimensions of our laser system are about 15 cm×20 cm×10 cm. This kind of laser system can be applied in many important applications, such as atomic interferometer and cold atomic clock.展开更多
The techniques used for the fabrication of photonic integrated circuit(PIC) chip are introduced briefly.Then a four channel DFB laser array integrated with MMI coupler and semiconductor optical amplifier(SOA) fabricat...The techniques used for the fabrication of photonic integrated circuit(PIC) chip are introduced briefly.Then a four channel DFB laser array integrated with MMI coupler and semiconductor optical amplifier(SOA) fabricated with butt-joint technique,varied ridge width and holographic exposure techniques is reported.展开更多
文摘Modulation bandwidth enhancement in a directly modulated two-section distributed feedback(TS-DFB)laser based on a detuned loading effect is investigated and experimentally demonstrated.The results show that the 3-dB bandwidth of the TS-DFB laser is increased to 17.6 GHz and that chirp parameter can be reduced to 2.24.Compared to the absence of a detuned loading effect,there is a 4.6 GHz increase and a 2.45 reduction,respectively.After transmitting a 10 Gb/s non-return-to-zero(NRZ)signal through a 5-km fiber,the modulation eye diagram still achieves a large opening.Eight-channel laser arrays with precise wavelength spacing are fabricated.Each TS-DFB laser in the array has side mode suppression ratios(SMSR)>49.093 dB and the maximum wavelength residual<0.316 nm.
基金This work was supported by National Key Research and Development Program of China(2018YFB2201101)the Strategic Priority Research Program of Chinese Academy of Sciences,Grant No.XDB43000000Beijing Municipal Science&Technology Commission,Administrative Commission of Zhongguancun Science Park No.Z201100004020004。
文摘In this work,a hybrid integrated optical transmitter module was designed and fabricated.A proton-exchanged Mach–Zehnder lithium niobate(LiNbO_(3))modulator chip was chosen to enhance the output extinction ratio.A fiber was used to adjust the rotation of the polarization direction caused by the optical isolator.The whole optical path structure,including the laser chip,lens,fiber,and modulator chip,was simulated to achieve high optical output efficiency.After a series of process improvements,a module with an output extinction ratio of 34 dB and a bandwidth of 20.5 GHz(from 2 GHz)was obtained.The optical output efficiency of the whole module reached approximately 21%.The link performance of the module was also measured.
基金Supported by the National Key Research and Development Program of China under Grant No 2017YFB0405301the National Natural Science Foundation of China under Grant Nos 61604144 and 61504137
文摘We experimentally demonstrate an In P-based hybrid integration of a single-mode DFB laser emitting at around 1310 nm and a tunneling diode. The evident negative differential resistance regions are obtained in both electrical and optical output characteristics. The electrical and optical bistabilities controlled by the voltage through the tunneling diode are also measured. When the voltage changes between 1.46 V and 1.66 V, a 200-mV-wide hysteresis loop and an optical power ON/OFF ratio of 17 dB are obtained. A side-mode suppression ratio of the integrated device in the ON state is up to 43 dB. The tunneling diode can switch on/off the laser within a very small voltage range compared with that directly controlled by a voltage source.
文摘A new all-optical flip-flop based on a nonlinear Distributed feedback (DFB) structure is proposed. The device does not require a holding beam. A nonlinear part of the grating is detuned from the remaining part of the grating and has negative nonlinear coefficient. Optical gain is provided by an injected electrical current into an active layer. In the OFF state, due to the detuned section, no laser light is generated in the device. An injected optical pulse reduces the detuning of the nonlinear section, and the optical feedback provided by the DFB structure generates a laser light in the structure that sustains the change in the detuned section. The device is switched “OFF” by detuning another section of the grating by a Reset pulse. The Reset pulse reduces the refractive index of that section by the generation of electron-hole pairs. The Reset pulse wavelength is adjusted such that the optical gain provided by the active layer at that wavelength is zero. The Reset pulse is prevented from reaching the nonlinear detuned section by introducing an optical absorber in the laser cavity to attenuate the pulse. The device is simulated in time domain using General Purpose Graphics Processing Unit (GPGPU) computing. Set-Reset operations are in nanosecond time scale.
基金Supported by National Natural Science Foundation of Chinathe Trans-Century Training Porgramme Foundation for Talents of the State Education Commission.
文摘In this paper,the fabrication of 1.3μm InGaAsP/InP gain-coupled DFB lasers with lossgrating is reported for the first time.A technique of regrowth on corrugated surface usingLPE is developed.By using GaAs as the cover of thermal protection and controlling theamount of the super cooling,high quality epitxial layers on corrugated surface are obtained.The oxide stripe lasers with a stripe width of 20μm are fabricated.Single-mode oscillation isachieved at 1.293μm,and a high single-mode oscillation yield is also obtained.
基金supported by the National Key R&D Program of China(No.2020YFB2205804)the National Natural Science Foundation of China(Nos.62273355,61975075,61975076,and 62004094)+1 种基金the Natural Science Foundation of Jiangsu Province of China(No.BK20200334)the Jiangsu Science and Technology Project(No.BE2017003-2)。
文摘The stable long-distance transmission of radio-frequency(RF)signals holds significant importance from various aspects,including the comparison of optical frequency standards,remote monitoring and control,scientific research and experiments,and RF spectrum management.We demonstrate a scheme where an ultrastable frequency signal was transmitted over a 50 km coiled fiber.The optical RF signal is generated using a two-section distributed feedback(DFB)laser for direct modulation based on the reconstruction equivalent chirp(REC)technique.The 3-dB modulation bandwidth of the two-section DFB laser is 18 GHz and the residual phase noise of-122.87 dBc/Hz is achieved at 10-Hz offset frequency.We report a short-term stability of 1.62×10^(-14)at an average time of 1 s and a long-term stability of 6.55×10^(-18)at the measurement time of 62,000 s when applying current to the front section of the DFB laser.By applying power to both sections,the stability of the system improves to 4.42×10^(-18)within a testing period of 56,737 s.Despite applying temperature variations to the transmission link,long-term stability of 8.63×10^(-18)at 23.9 h can still be achieved.
基金This work was supported in part by the National Key R&D Program of China(No.2018YFA0704402)National Natural Science Foundation of China(Nos.61974165 and 61975075)+1 种基金National Natural Science Foundation of China for the Youth(No.62004105)Science and Technology Project,and Natural Science Foundation of Jiangsu Province(No.BE2019101)。
文摘We demonstrate a high-resolution frequency-modulated continuous-wave dual-frequency LIDAR system based on a monolithic integrated two-section(TS) distributed feedback(DFB) laser. In order to achieve phase locking of the two lasers in the TS-DFB laser, the sideband optical injection locking technique is employed. A high-quality linear frequency-modulated signal is achieved from the TS-DFB laser. Utilizing the proposed LIDAR system, the distance and velocity of a target can be measured accurately. The maximum relative errors of distance and velocity measurement are 1.6% and 3.18%, respectively.
文摘A more than 12 mW highly efficient fibre-DFB laser operating at 1618.3 nm is fabricated and characterised. Its high-power, low-noise and single-polarisation characteristics make it very suitable WDM-source for L-band transmission.
基金Project supported by the National Natural Science Foundation of China(Nos.60776051,60376033)the Beijing Municipal Natural Science Foundation of China(No.4082007)the Beijing Municipal Education Committee of China(Nos.KM200910005001, KM200710005015).
文摘A novel cascaded DFB laser,which consists of two serial gratings to provide selectable wavelengths,is presented and analyzed by the transfer matrix method.In this method,efficient facet reflectivity is derived from the transfer matrix built for each serial section and is then used to simulate the performance of the novel cascaded DFB laser through self-consistently solving the gain equation,the coupled wave equation and the current continuity equations.The simulations prove the feasibility of this kind of wavelength selectable laser and a corresponding designed device with two selectable wavelengths of 1.51μm and 1.53μm is realized by experiments on InP-based multiple quantum well structure.
文摘EAM-DFB monolithic light sources with the coupling waveguide between laser and modulator have been developed. 10mw output light power at 90mA and 18dB extinction ratio at -2V has been achieved.
基金This work was supported by National "973" Project of China (No. G20000683-1)the National Natural Science Foundation of China (No. 90401025)the National "863" Program of China (No. 2002AA312150).
文摘A novel distribute feedback (DFB) laser which gave two different wavelengths under two distinct work conditions was fabricated. The laser consists of two Bragg gratings with different periods corresponding to wavelength spacing of 20 nm in an identical active area. When driving current was injected into one of the different sections separately, two different wavelengths at 1542.4 and 1562.5 nm were realized. The side mode suppression ratio (SMSR) of 45 dB or more both for the two Bragg wavelengths were achieved. The fabricating process of the laser was just the samp as that of traditional DFB laser diode. This device can be potentially used in coarse wavelength division multiplexer (CWDM) as a promising light source and the technology idea can be used to enlarge the transmission capacity in metro area network (MAN).
文摘We propose, design, and realize a compact stabilized laser system that can be tuned within 24 GHz automatically. This laser system consists of two distributed feedback （DFB） lasers, one of which is reference and locked to the D2 line of Rb87, the other laser is a slave that is locked to the reference laser via a loop servo. We measured the frequency of the beating signal of the two lasers and generated an error signal, which controlled the frequency of the slave laser to close the loop. We compressed the fluctuation of the beating signal’s frequency to less than 1 MHz. Furthermore, the system can also automatically determine and control whether the slave is red detuned or blue detuned to the reference. The dimensions of our laser system are about 15 cm×20 cm×10 cm. This kind of laser system can be applied in many important applications, such as atomic interferometer and cold atomic clock.
基金supported by the National Hi-Tech Research and Development Program of China ("863" Project)(Grant Nos. 2011AA010303,2012AA012203)the National Basic Research Program of China ("973" Project)(Grant No. 2011CB301702)the National Natural Science Foundation of China (Grant Nos. 61021003,61090392)
文摘The techniques used for the fabrication of photonic integrated circuit(PIC) chip are introduced briefly.Then a four channel DFB laser array integrated with MMI coupler and semiconductor optical amplifier(SOA) fabricated with butt-joint technique,varied ridge width and holographic exposure techniques is reported.
