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High Power $1.5\mu$ m Pulsed Laser Diode With Asymmetric Waveguide and Active Layer Near <i>p</i> -cladding
摘要： We report ?rst experimental results on a high-power pulsed semiconductor laser operating in the eye-safe spectral range (wavelength around 1.5 μm) with an asymmetric waveguide structure. The laser has a bulk active layer positioned very close to the p-cladding in order to eliminate current-induced nonuniform carrier accumulation in the p-side of the waveguide and the associated carrier losses. Moderate doping of the n-side of the waveguide is used to strongly suppress nonuniform carrier accumulation within this part of the waveguide. Highly p-doped InP p-cladding facilitates low series resistance. An as-cleaved sample with a stripe width of 90 μm exhibits an output power of about 18 W at a pumping current amplitude of 80 A. Theoretical calculations, validated by comparison to experiment, suggest that the performance of lasers of this type can be improved further by optimization of the waveguide thickness and doping as well as improvement of injection ef?ciency.
关键词： Laser radar,optical pulse generation,semiconductor lasers
更新于2025-09-11 14:15:04
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Recent advances in the photonic integration of mode-locked laser diodes
摘要： Mode-locked ?ber and solid state lasers have played an essential role in several scienti?c and technological developments. The integration of mode-locked lasers on chips could enable their use in a wide range of applications. The advancement of semiconductor mode-locked laser diodes has been going on for several decades, but has recently seen the development of novel devices based on generic InP and III-V-on-silicon photonic integration platforms. These photonic integration platforms enable the use of standardized components and low-loss waveguides within the laser cavity, allowing for the design of advanced extended cavities. In this manuscript we give a review of these novel devices and compare their performance.
关键词： Semiconductor lasers,silicon photonics,quantum well lasers
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - A Functional Mapping for Passively Mode-Locked Semiconductor Lasers
摘要： Passive Mode-locking (PML) of semiconductor lasers is a most promising method for the generation of low repetition rate picosecond pulses, which is of paramount importance for a number of applications. Because of the long round-trip times and fast time scales of the ?eld evolution this regime is computationally very intensive. Studying the pulse train dynamics and temporal jitter can require simulations over hundreds of thousands of round-trips. If, in addition to the longitudinal dynamics, transverse diffraction of the beam or thermal processes are considered, the problem becomes intractable. The Haus master equation [1] is a widely used approach to study PML. By considering a partial differential equation (PDE) model one can restrict the analysis of the ?eld to a small temporal interval around the pulse, making the approach computationally ef?cient. Yet this method, when applied to a particular design, provides only qualitative predictions due to the many simplifying hypothesis involved. We present a method that combines the accuracy of ?rst principle time-delayed models with the computational ef?ciency of the Haus master equation. Our method is based upon computing only the so-called fast stage in the vicinity of the pulse where stimulated emission is dominant, while using an approximate analytical solution of the dynamics during the slow stages in-between pulses. We illustrate the idea of the functional mapping (FM) using the DDE model of [2] that considers unidirectional propagation in a ring laser, however it can be used in other models as well, including approaches using delay algebraic equations (DAEs) like [3]. The equations for the ?eld amplitude A, the gain G and the absorption Q read ˙A γ = ?A +Y (t ? τ) , ˙Q = Q0 ? Q ? s (cid:2) 1 ? e (cid:3) ?Q |A|2 , (1) (3) ˙G = Γ (G0 ? G) ? e ?Q (cid:2) eG ? 1 (cid:3) |A|2 , (2) (cid:4) Y (t) = √ κ exp 1 ? iα 2 G (t) ? 1 ? iβ 2 (cid:5) Q (t) A (t) . (4) We wrote Eq. (1) in a form that makes apparent that the forcing ?eld Y (t ? τ) de?ned in Eq. (4) is a nonlinear function that is known over a whole interval of duration τ. Since gain G and losses Q are functions of A, Y involves only the past values of the ?eld, i.e., Y (t ? τ) = g [A (t ? τ)]. Knowing the forcing term Y, Eq. (1) can be solved for A over an interval of duration τ. Integrating Eqs. (1-4), not over the whole round-trips, but only in a selected time interval in the pulse vicinity, is at the core of the functional mapping (FM) method. The speedup of the FM is equal to the ratio of the actual integration domain 2δ and of the full round-trip τ, i.e., m = τ/ (2δ ). Taking a domain of duration 2δ = 5τp, a pulse with of τp = 1 ps at a repetition rate of τ ?1 = 1 GHz, yields a speedup m = 200, i.e., a 24 hours simulation with, e.g., slow thermal effects or transverse diffraction could potentially be achieved in a few (～ 7) minutes.
关键词： picosecond pulses,semiconductor lasers,Passive Mode-locking,computational efficiency,functional mapping
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Modeling of the Ultra-Stable Operating Regime in Fourier Domain Mode Locked (FDML) Lasers
摘要： Fourier domain mode locked (FDML) ?ber lasers are broadband wavelength-swept ring systems with record sweep speeds. Lasing is achieved by synchronizing the roundtrip time of the optical ?eld in the ?ber delay cavity with the sweep period of a tunable Fabry-P′erot (FP) bandpass ?lter. Since their invention in 2006, FDML lasers have dramatically enhanced the capabilities of optical coherence tomography (OCT) and various sensing applications. However, the physical coherence limits, such as the maximum achievable coherence length, are yet unknown. An important breakthrough in reaching this limit is a recently experimentally demonstrated highly coherent operation mode over a bandwidth of more than 100 nm [1], referred to as the sweet spot. The sweet spot operation mode is characterized by nearly shot-noise limited ?uctuations in the intensity trace of the laser with signi?cantly enhanced coherence properties, whereas in conventional FDML laser systems the intensity trace is distorted by high frequency noise which negatively affects the coherence length. This ultra-low noise operating regime was generated by an almost perfect compensation of the ?ber dispersion with a manually ?ne tuned chirped ?ber Bragg grating and a highly synchronized sweep rate of the FP ?lter with an accuracy in the range of mHz. Polarization effects were controlled with a polarization maintaining semiconductor optical ampli?er (SOA) gain medium and a polarization controller.
关键词： Fourier domain mode locked (FDML) lasers,sweet spot operation mode,coherence length,semiconductor optical amplifier (SOA),polarization controller,optical coherence tomography (OCT)
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Square Pulse and Harmonic Ultrashort Pulse Generation in Semiconductor Optical Amplifier-Based Mamyshev Oscillator
摘要： Modulation instability is responsible for the symmetry breaking of homogeneous spatio-temporal states or wave envelopes and the formation of stable patterns in a variety of physical media. Recently, by using this phenomenon in laser physics, remarkable developments have been made based on the use of the effect of self-phase modulation in Mamyshev oscillator [1-3]. The oscillator is designed using a spectral filter and a gain to compensate for filtering losses. By mismatching spectral filter offsets, entire cavity works as an element with the power-dependent transmission, suppressing the continuous wave lasing and favouring the formation of ultrashort pulses. Recently application of semiconductor optical amplifiers (SOA) as a gain media in fibre lasers as a gain medium has drawn a new wave of research attention due to their potential applications in telecommunications, all-optical square-wave clocks, range finding, and optical sensing. In this work, we developed a Mamyshev oscillator based on SOA operating in square pulses and high harmonic generation at 1550 nm.
关键词： high harmonic generation,Mamyshev oscillator,semiconductor optical amplifiers,square pulses,Modulation instability
更新于2025-09-11 14:15:04
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[IEEE 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - Fukuoka, Japan (2019.7.7-2019.7.11)] 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - Data Suppression in Wavelength-Reuse WDM-PON Using Semiconductor Optical Amplifier with Faraday Rotator Mirror and Fabry-Perot Etalon
摘要： We experimentally study data suppression characteristics of a semiconductor optical amplifier with a Faraday rotator mirror used for wavelength-reuse WDM-PON. Bidirectional transmission over 10 km assisted by spectral trimming using a Fabry-Perot etalon is demonstrated.
关键词： TWDM-PON,Access Network and Subsystem,OFDM-PON,Future high capacity and long-reach access networks including WDM-PON,Semiconductor optical amplifiers
更新于2025-09-11 14:15:04
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Synthesis, chemical, theoretical studies, electrochemical, electrical and optical characterization of novel oligomer 2,2’-((1E,1’E)(2,5-bis(octyloxy)-1,4-phenylenevinylene)bis(6-(E)-2-(vinylquinolin))quinoline for OLED applications
摘要： A fluorescent pentamer 5QnQnPV with one phenyl central donor group surrounded by four quinoline acceptor groups set in a quadrupolar A-π-A-π-D-π-A-π-A electronic structure was synthesized. This compound is an organic semiconductor and shows a wide band fluorescence emission that spans from the blue to the red region with a maximum peak centered at 509 nm. In addition, its HOMO (? 5.4 eV)/LUMO (? 3.5 eV) energy values, determined by cyclic voltammetry, optical gap EgOpt of 2.18 and theoretical DT-DFT studies indicated a potential for OLED fabrication. When such device was made with a ITO/PEDOT:PSS/5QnQnPV/Al configuration it displayed a maximum electroluminescent response at 860 nm. The structural and physical characterization of this compound was performed using 1H and 13C Nuclear Magnetic Resonance, Fourier Transformed Infrared Spectroscopy, Mass Spectroscopy and Atomic Force Microscopy.
关键词： organic semiconductor,Atomic Force Microscopy,Fourier Transformed Infrared Spectroscopy,Mass Spectroscopy,electroluminescent response,fluorescent pentamer,Nuclear Magnetic Resonance,OLED
更新于2025-09-11 14:15:04
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Laser self-mixing interferometry for micro-vibration measurement based on inverse Hilbert transform
摘要： A novel micro-vibration reconstruction method based on inverse Hilbert transform is presented. By inversing either side of the SMI signal after Hilbert transform, micro-vibration can be reconstructed quickly and conveniently. In the paper, the principle of inverse Hilbert transform algorithm is studied. And, the effectiveness of the method is verified through simulated signals, and several experiments are carried out, including the self-mixing signal affected by speckle effect. The experimental results show that the external cavity phase can be rapidly extracted by inverse Hilbert transform algorithm, and the relative error is no more than 7%.
关键词： Micro-vibration reconstruction,Phase extraction,Self-mixing interferometry,Semiconductor laser diode
更新于2025-09-11 14:15:04
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Thin film Sn2S3 via chemical deposition and controlled heating - its prospects as a solar cell absorber
摘要： As a semiconductor of “earth-abundant” elements, Sn2S3 with a bandgap (Eg) close to 1 eV merits attention, but a method to prepare phase-pure thin film remains elusive. We report the formation of Sn2S3 thin film of 360 nm in thickness by heating chemically deposited tin sulfide thin films at 450 oC during 30 – 45 min in presence of sulfur at a pressure, 75 Torr of nitrogen. Energy dispersive x-ray emission spectra and grazing incidence x-ray diffraction established a reaction route for this conversion of SnS completely to Sn2S3 via an intermediate phase, SnS2. The optical bandgap of the material is 1.25 eV (indirect) and 1.75 eV (direct, forbidden). The optical absorption suggests a light-generated current density of 30 mA/cm2 for the Sn2S3 film (360 nm) as a solar cell absorber. Thin film Sn2S3 formed in 30 min heating has a p-type electrical conductivity in the dark of 1x10–4 Ω–1 cm–1, which increases to 3x10–4 Ω–1 cm–1 in 0.2 s under 800 W/m2 tungsten-halogen illumination. An estimate made for its mobility-lifetime product is, 6x10–6 cm2 V–1. We discuss the prospects of this material for solar cells.
关键词： SnS-CUB,Sn2S3,semiconductor thin film,chemical deposition,energy conversion,ottemannite,cubic tin sulfide,renewable energy,optical and electrical properties,solar cells
更新于2025-09-11 14:15:04
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Investigation of Current-Driven Degradation of 1.3 μm Quantum-Dot Lasers Epitaxially Grown on Silicon
摘要： This work investigates the degradation processes affecting the long-term reliability of 1.3 μm InAs quantum-dot lasers epitaxially grown on silicon. By submitting laser samples to constant-current stress, we were able to identify the physical mechanisms responsible for the optical degradation. More specifically, the samples (i) exhibited a gradual increase in threshold current, well correlated with (ii) a decrease in sub-threshold emission, and (iii) a decrease in slope efficiency. These variations were found to be compatible with a diffusion process involving the propagation of defects toward the active region of the device and the subsequent decrease in injection efficiency. This hypothesis was also supported by the increase in the defect-related current conduction components exhibited by the electrical characteristics, and highlights the role of defects in the gradual degradation of quantum dot laser diodes. Electroluminescence measurements were used to provide further insight in the degradation process.
关键词： silicon photonics,semiconductor defects,degradation,reliability,Quantum dots,laser diodes
更新于2025-09-11 14:15:04