A GaInAsP/InP tapered-waveguide semiconductor laser amplifierintegrated with a 1.5 μm distributed feedback laser

A GaInAsP/InP index-guided type tapered-waveguide traveling-wave semiconductor laser amplifier (TTW-SLA) with exponential taper structure was realized for the first time and its integration with a 1.5 μm wavelength phase adjusted DFB laser was demonstrated. A reasonable amount of the single-pass gain, which was limited by the residual reflectivity at the output end of the amplifier region, was obtained with no serious problem with the lasing spectrum. A narrow beam divergence of FWHM=5.5° and stable longitudinal mode operation were obtained with the output waveguide width of 20 μm by adopting both a window structure and 7° angled facets. This value agrees well with the theoretically calculated one and proves that single transverse-mode propagation can be attained by an exponentially tapered TTW-SLA with a very wide output end     

Efficient integrated Nd3+ fiber laser

An efficient, integrated, low-threshold, tunable, laser-diode pumped Nd³⁺ fiber laser has been fabricated. The integrated fiber laser incorporated two highly reflecting intracore Bragg reflectors, which were formed holographically by transversely exposing the core to a UV two-beam interference pattern. When the fiber laser was diode pumped, a maximum output of 2.3 mW was observed at 1.088 μm, and a slope efficiency of 41% was measured     

GaInAsP/InP semiconductor vertical GRIN-lens for semiconductoroptical devices

A GaInAsP/InP vertical GRIN-lens (VGL), which is suitable for monolithic integration with semiconductor laser diodes (LDs) or semiconductor laser amplifiers (SLAs), was fabricated for the first time. A narrow FWHM of vertical far-field pattern of 6 degree was experimentally obtained with 8 layers of GRIN core region (8 μm thick) and InP cladding layers. An integration of this VGL with a taper waveguide SLA with the output width of 10 μm was also demonstrated     

Optical amplification in Er3+-doped single-mode fluoridefiber

The amplification characteristics at around 1.5 μm of a 0.9-m-long, 1000-p.p.m Er³⁺-doped single-mode fluoride fiber are discussed. By using 1.48-μm laser diodes with 55-mW launched output as a pump source, a gain of 1.75 dB was obtained at 1.530 μm. A broad bandwidth of 40 nm was obtained, which may be suitable for wavelength-division multiplexing (WDM) system use     

光泵CH3F和D2O远红外脉冲激光器

本文叙述了无镜远红外激光器的结构及其实验结果。用可调谐TEA CO_2激光器作为泵浦源,其输出能量在9P(20),9R(22)线上均可达1J左右。用CO_29P(20)线泵浦CH_3F分子,获得了能量为0.5mJ,波长为496μm的激光输出;用9R(22)线泵浦D_2O分子,获得了能量为1mJ,波长为385μm的激光输出。输出能量和波长是分别用热电堆和Fabry-Perot干涉仪测量的。     

Surface-emitting multiple quantum well distributed feedback laserwith a broad-area grating coupler

A surface-emitting laser diode with a 100×200 μm² grating coupler was fabricated. Narrow beam divergence angles of 2°×0.32° and a maximum output power of 210 mW were obtained     

Efficient pulsed first-overtone CO laser operating within thespectral range of 2.5-4.2 μm

Output characteristics of a single-pulse e-beam controlled discharge laser operating on the first-overtone (FO) transitions (Δν=2) of CO molecules have been studied both experimentally and theoretically. Various sets of dielectric mirrors with high reflectivity in the range of the overtone spectrum have been used for the laser resonator. Multiwavelength lasing has been obtained in the wide spectral range of 2.5-4.1 μm on vibrational transitions from 6→4 up to 37→35. A maximum output efficiency of 11%, the highest ever published for a FO CO laser, has been experimentally obtained for the broad-band multiline FO CO laser. Maximum specific output energy is 50 J/1 Amagat. FO CO lasing was observed within a predischarge gas temperature range of 100-220 K. Spectral characteristics of the overtone laser operating on a selected set of vibrational bands have been analyzed theoretically. Theoretical calculations based on the experimental data predict that multiline FO CO laser efficiency can be increased up to 20%. Experiments with a single-pulse FO CO laser using a diffraction grating as a frequency-selective element demonstrated the feasibility of developing a frequency-tunable single-line FO CO laser. Tunable FO CO lasing on wavelengths from 2.7 up to 4.2 μm corresponding to vibrational transitions from 13→11 up to 38→ 36 was obtained. The maximum specific output energy came up to 2.8 J/1 Amagat, with single-line output efficiency being up to 0.6%     

Tunable ultraviolet generation using a femtosecond 250 kHzTi:sapphire regenerative amplifier

A mode-locked Ti:sapphire regenerative amplifier system pumped with a single argon ion laser produces μJ energy femtosecond pulses of 800 nn wavelength at up to 300 kHz repetition rate. This output is used to generate tunable femtosecond pulses in the ultraviolet to as short as 240 mn by using a combination of harmonic generation, white-light continuum generation and parametric amplification. A variety of techniques to access different parts of the UV spectrum are presented     

155 W CW optical power from 1 cm monolithic AlGaAs/InGaAs laserdiode array

155 W continuous-wave output power from a 1 cm wide monolithic AlGaAs/InGaAs laser diode array with an emitting aperture of 4800 μm has been demonstrated at a cooling water temperature of 3°C. A continuous-wave output power of 72 W was achieved at room temperature with an emitting aperture of 1600 μm. High T₀ was observed for the laser structures     

Continuous-wave power performance of a 2.47-μmCr2+:ZnSe laser: experiment and modeling

Power performance of a continuous-wave Cr²⁺:ZnSe laser was investigated experimentally and numerically at 2.47 μm. In the experiments, an astigmatically compensated z-cavity with a 3% transmitting output coupler produced as high as 250 mW of output power when excited by a NaCl:OH^$color-center laser at 1.58 μm. The measured absorbed power slope efficiency was 24.2%. Experimental pump absorption saturation and laser efficiency data were analyzed by using a numerical model to determine the absorption, emission, and excited-state absorption cross-sections. Simulations were then performed to investigate the dependence of the output power on crystal and resonator parameters. Results indicate that optimum power performance should be obtained with a 1.5-cm-long crystal which has a total unsaturated absorption of 86%. Finally, the optimum output coupling of the resonator was determined to be 10%     

Spot-size converted 1.3 μm laser with butt-jointed selectivelygrown vertically tapered waveguide

A 1.3 μm laser has been developed with a butt-jointed selectively grown spot-sire converter (SSC). The SSC vertically tapered waveguide and strained multiquantum well (MQW) active region are independently optimised. The laser was buried with semi-insulating InP to reduce optical loss in the SSC. A threshold current of 7 mA and an output power of >20 mW were obtained. Minimum coupling loss to a flat-end fibre of 1.06 dB was achieved. Long-term stability was also confirmed     

A 170 J electron beam pumped XeF(C→A) laser

A pulse output energy of 170 J has been achieved from an XeF(C→A) laser system, pumped by a pair of counterpropagating, three-meter-long electron beams. This represents a record for all types of pumping, for this excimer system. Energy was extracted from a volume of ~100 L, using a free-running stable oscillator. No evidence of laser oscillations on the competing XeF(B→X) transition was observed. Within the extraction volume the laser gas was pumped at a rate of 140 kW/cm³ (time average value), for a period of 1.7 μs. The optical cavity was folded, giving a gain length of 6 m. The optical pulse duration was 0.8 μs (full width at half maximum), and the observed flux buildup time of ~1 μs was consistent with modeling and a measurement of the net gain. The specific output energy was 1.7 J/L which is comparable to that achieved in previous, small scale experiments at somewhat higher pump rate. The results confirm the volumetric scalability of the electron beam pumped XeF(C→A) laser system to high output energy per pulse, and the feasibility of operating this system at a low electron beam pump rate which relaxes constraints on the design of the electron gun and pulse power subsystems in a high output energy device. Means for extending the laser pulse duration and increasing the output energy of the specific test device are discussed. An output energy of ~1000 J is projected for an optimized gas cell width, for full size resonator mirrors, and with injection     

Low threshold InGaAs/GaAs 45° folded cavity surface-emittinglaser grown on structured substrates

A novel folded cavity surface-emitting laser structure integrating a horizontal cavity InGaAs/GaAs laser grown on a structured substrate with a high reflectivity Bragg reflector has been fabricated. Devices with threshold currents of 8 mA and CW wall plug efficiencies at 5% at 6 mW output power have been demonstrated at a wavelength of 0.99 μm. By combining a cleaved uncoated mirror with the 45° deflecting mirror the authors have obtained threshold current as low as 5 mA for a device 450 μm long     

Efficient high power operation of erbium 3 μm fibre laserdiode-pumped at 975 nm

Efficient CW operation of a 2.71 μm Er,Pr:ZBLAN double-clad fibre laser pumped with a single diode laser operating at a wavelength of 975 nm is described. A maximum output power of 0.5 W and a slope efficiency of 25% (with respect to the launched pump power) were obtained. Threshold pump powers of <200 mW launched were measured and consistent relaxation oscillations in the output from the fibre laser indicate the presence of a saturable absorption mechanism     

光泵CF4 16微米激光器

本文介绍了由 TEA CO_2激光器的9R(12)跃迁线泵浦冷却的 CF_4分子,获得 16μm激光输出。泵浦光用限孔光阑得到TEMoo单横模,由低气压CO_2增益池压缩线宽,并与光泵腔良好的模式匹配下,以700mJ的泵浦源能量获得25mJ左右的16μm激光输出能量。光量子转换效率达7％左右。激光脉宽窄于150ns,该器件可在约0.5Hz重复率下,以20mJ的输出能量运转数千次。     

1.3-μm GaInAsP/InP buried-ridge-structure laser and itsmonolithic integration with photodetector using reactive ion beametching

A 1.3 μm GaInAs/InP BRS laser is monolithically integrated with a photodiode. reactive ion beam etching technique (RIBE) is used for the realization of the laser mesa stripe and for the separation of the laser and the photodetector sections. Influence of the laser-detector gap width, the detector facet inclination, and the laser beam waist on the coupling efficiency between LD and PD are discussed theoretically and experimentally. Coupling efficiency as high as 50 μA/mW is obtained by optimizing the structure. A packaged pigtailed integrated LD-PD is realized, in which the signal emitted from the rear laser facet is detected by the integrated photodiode and used to stabilize the laser output power, through a hybrid feedback circuit, to within 0.1% over 55°C temperature range     

Solid-state laser pumping of 1.5-μm optical amplifiers andsources for lightwave video transmission

An optical power amplifier and a laser source are demonstrated at 1.5 μm. A diode-pumped Nd:YAG laser is used as the pumping source for an Er/Yb co-doped gain medium. The power scaling advantages of this approach are demonstrated. Up to +21 dBm of output power is obtained from the Er/Yb amplifier and up to +19 dBm is obtained from the laser source. The Er/Yb power amplifier was deployed in a 42-channel AM link with 40 km of fiber, and an optical loss budget of 18 dBm was demonstrated     

Asymmetric output characteristics in 1.3-μm spot-size convertedlaser diodes

A spot-size converted laser diode (SSC-LD) with a vertically tapered passive waveguide structure was fabricated by butt-joint-built-in (BJB) coupling and selective area metal organic chemical vapor deposition growth. A high coupling efficiency exceeding 50% and 1-dB alignment tolerance of ±2.5 μm were obtained at a distance of 20 μm between a flat-end single-mode fiber and the SSC-LD. Experimental results show that the asymmetric output property can be described by the radiation mode added to the guide mode and spatial hole-burning in the active region     

Low-noise 0.78 μm-band laser diode unit containing Faradayrotator

A small, low-noise 0.78 μm-band laser diode unit, containing a Faraday rotator which suppresses optical feedback, was developed. Stable low-noise characteristics were realised within the 3 mW to 10 mW output power. Greater than 40 dB signal/noise ratio was obtained in an optical video disc with this unit