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Comparison of Self-Injection Locking of DFB-LD by Optical Fiber and Optical Waveguide Ring Resonators
摘要： Utilizing the frequency selection characteristic of ring resonators, self-injection-locking linewidth narrowing and frequency stabilization of distributed feedback laser diodes (DFB-LDs) can be achieved under the aid of ring resonators. In this paper, the self-injection-locking effects of a DFB-LD realized by two fiber ring resonators and an optical waveguide ring resonator are compared. The influences of the resonant peak bandwidth and transmission on linewidth narrowing are demonstrated. It is shown that the mode hopping can be significantly suppressed by employing the optical waveguide ring resonator. This is of great significance for practical applications and integration of the self-injection-locked DFB-LDs.
关键词： Self-injection locking,distributed feedback laser diode,phase noise,linewidth narrowing,mode hopping,ring resonator
更新于2025-09-12 10:27:22
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InGaN/GaN Distributed Feedback Laser Diodes with Surface Gratings and Sidewall Gratings
摘要： A variety of potential applications such as visible light communications require laser sources with a narrow linewidth and a single wavelength emission in the blue light region. The gallium nitride (GaN)-based distributed feedback laser diode (DFB-LD) is a promising light source that meets these requirements. Here, we present GaN DFB-LDs that share growth and fabrication processes and have surface gratings and sidewall gratings on the same epitaxial substrate, which makes LDs with di?erent structures comparable. By electrical pulse pumping, single-peak emissions at 398.5 and 399.95 nm with a full width at half maximum (FWHM) of 0.32 and 0.23 nm were achieved, respectively. The surface and sidewall gratings were fabricated alongside the p-contact metal stripe by electrical beam lithography and inductively coupled plasma etching. DFB LDs with 2.5 μm ridge width exhibit a smaller FWHM than those with 5 and 10 μm ridge widths, indicating that the narrow ridge width is favorable for the narrowing of the line width of the DFB LD. The slope e?ciency of the DFB LD with sidewall gratings is higher than that of surface grating DFB LDs with the same ridge width and period of gratings. Our experiment may provide a reliable and simple approach for optimizing gratings and GaN DFB-LDs.
关键词： surface gratings,GaN laser diode,sidewall gratings,distributed feedback (DFB)
更新于2025-09-11 14:15:04
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InAs/GaAs Quantum Dot Dual-Mode Distributed Feedback Laser Towards Large Tuning Range Continuous-Wave Terahertz Application
摘要： In this paper, a laterally coupled distributed feedback (LC-DFB) laser based on modulation p-doped multiple InAs/GaAs quantum dot (QD) structures has been fabricated. The device exhibits a high side-mode suppression ratio (SMSR) of > 47 dB and a high thermal stability of dλ/dT = 0.092 nm/K under continuous-wave (CW) operation, which is mainly attributed to the high material gain prepared by modulation p-doping and rapid thermal annealing (RTA) process, and the significantly reduced waveguide losses by shallow-etched gratings and its close proximity to the laser ridge feature in the LC-DFB laser. With this superior performance of the DFB laser, the wide tunable dual-wavelength lasing operation has been obtained by delicately defining different periods for the grating structures on the two sides of the laser ridge or combining the reduced laser cavity length. The wavelength spacing between the two lasing modes can be flexibly tuned in a very wide range from 0.5 to 73.4 nm, corresponding to the frequency difference from 0.10 to 14 THz, which is the largest tuning range by the utilization of single device and hence providing a new opportunity towards the generation of CW THz radiation.
关键词： Semiconductor lasers,Lasers,Distributed feedback,Optoelectronics,Terahertz imaging,Quantum well, wire, and dot devices
更新于2025-09-11 14:15:04
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Electronically Tunable Distributed Feedback (DFB) Laser on Silicon
摘要： An electronically tunable distributed feedback (DFB) laser heterogeneously integrated on a silicon photonics platform is experimentally demonstrated. Tuning is achieved through carrier injection into the tuning layer of a tunable twin-guide III–V membrane on silicon. A 2 nm continuous tuning range is achieved with a single tuning current. Continuous-wave single-mode laser operation with a side-mode suppression ratio larger than 44 dB across the tuning range is obtained. Measured wavelength switching times are on the order of 3 ns and non-return-to-zero on-o? keying direct modulation at 12.5 Gbit s?1 is readily achieved. This work can be a major advance toward the realization of optical burst or packet switching systems for future data center networks.
关键词： silicon photonics,electronic wavelength tuning,distributed feedback lasers,semiconductor lasers
更新于2025-09-11 14:15:04
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Semiconductor Heterolasers with Double-Mirror Two-Dimensional Bragg Resonators
摘要： A double-mirror two-dimensional Bragg resonator design based on structures of planar geometry, which is typical of both band-to-band and quantum-cascade heterolasers, is suggested. The distinguishing feature of this design is the coupling between longitudinal and transverse energy flows in two-dimensional Bragg mirrors. The eigenmode spectrum of the structure is described. It is shown that the proposed design can be used for synchronizing radiation emitted in lasers and laser arrays.
关键词： Bragg structures,single-mode lasing,heterolaser,distributed feedback
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - High-Power Long-Waveguide 1300nm Directly Modulated DFB Laser for 45Gb/s NRZ and 50Gb/s PAM4
摘要： A 1300-nm high-speed high-power directly modulated distributed-feedback laser using floating feeding electrode has been demonstrated. A 5-μm-thick benzocyclobutene was used for planarization to float a coplanar waveguide, connecting a reversed-mesa ridge waveguide of a laser. Low parasitic capacitance was then formed. A long waveguide can thus be fabricated with low roll-off at high-frequency modulation, further enabling high-output optical power. A 250-μm-long waveguide was fabricated, leading to >28-mW optical power with linear operation and ?3-dB bandwidth of 26 GHz. Furthermore, improvement in high-frequency regime and the reduction near resonance peak were found, attaining a broadband and flat frequency response at high current. A 45-Gb/s non-return-to- zero and 50-Gb/s four-level pulse amplitude modulation with 35-km fiber transmission were successfully shown through mod- ulating high-output optical power.
关键词： Coplanar waveguide (CPW),distributed feedback (DFB) lasers,reversed-ridge waveguide (RRW),planarization
更新于2025-09-11 14:15:04
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Influence of Light Coupling Configuration and Alignment on the Stability of HWG-Based Gas Sensor System for Real-Time Detection of Exhaled Carbon Dioxide
摘要： A mid-infrared tunable diode laser absorption spectroscopy (TDLAS) gas sensor based on hollow waveguide (HWG) gas cell for real-time exhaled carbon dioxide (eCO2) detection is reported. A 2.73 μm distributed feedback (DFB) laser was used to target a strong CO2 absorption line, and wavelength modulation spectroscopy (WMS) with the second harmonic (WMS-2 f ) was used to retrieve the CO2 concentration with high sensitivity. The influence of different parameters, including coupling configuration of HWG, laser-to-HWG and HWG-to-detector coupling alignment on the stability of the HWG sensor is systematically studied. The HWG eCO2 sensor showed a fast response time of 2.7s, detection limit of 17 ppmv, and measurement precision of 20.9 ppmv with a 0.54 s temporal resolution. The eCO2 concentrations changed in breath cycles were measured in real time. The Allan variance indicated that the detection limit can reach 1.7 ppmv, corresponding to a detection sensitivity of 1.3×10?8 cm?1 Hz?1/2, as the integration time increases to 26 s. This work demonstrates the performance characteristics and merits of HWG eCO2 sensor for exhaled breath analysis and potential detection for other exhaled gases.
关键词： hollow waveguide,distributed feedback laser,carbon dioxide,Tunable diode laser absorption spectroscopy
更新于2025-09-11 14:15:04
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Time-modulated Periodic Systems with PT Symmetry
摘要： This work explores the effects of parity-time (PT) symmetry in time-modulated periodic systems. Mechanisms for dynamic tunability of exceptional points are presented. We show that synthetic linear momentum imparted by time-modulation leads to uni-directional exceptional points. Such structures could see application in uni-directional lasers with tunable directionality.
关键词： semiconductor lasers,photonic crystals,distributed feedback lasers,time-varying circuits,parity-time symmetry,time-varying systems,optical modulation
更新于2025-09-04 15:30:14