Modeling and measurements of the radiative characteristics of high-power /spl alpha/-DFB lasers

A new above-threshold model of /spl alpha/-DFB lasers is presented. It is based on a generalized beam-propagation method and takes into account spatial hole burning and self-heating effects. Up to moderate output powers, a good agreement between simulated and measured radiative characteristics is obtained. The theoretical model was used to design an optimized laser structure with a 4-mm-long cavity, which yielded a maximum output power of 3 W with a times-diffraction-limit factor of M/sup 2//spl ap/3.     

High-performance laser diodes with emission wavelengths above 1100 nm and very small vertical divergence of the far field

The effect of variations in the vertical structure on the performance of AlGaAs-GaAs laser diodes with an InGaAs quantum well (QW) emitting around 1120 nm was investigated. With very thick waveguide layers, more than 95% of the output power is enclosed in an angle smaller than 35/spl deg/. This allows the use of fast axis collimators with a small numerical aperture. Broad area laser diodes with 100-/spl mu/m stripe width, an optimized doping profile, and a double QW emit more than 12 W and show reliable operation at 5 W.     

7 W CW power from tensile-strainedGaAsyP1-y/AlGaAs (λ=735 nm) QW diode lasers

100 μm-stripe lasers with a tensile-strained GaAs_yP _1-y quantum well embedded in a low-loss AlGaAs large-optical-cavity structure provide a record-high CW power of 7 W at 735 nm from 2 mm-long devices. The transverse beam pattern has a narrow 25° beamwidth. Reliability tests at the 0.5 W CW power level suggest lifetimes >10⁴ h     

7.4 W continuous-wave output power of master oscillator power amplifier system at 1083 nm

A 1083 nm hybrid master oscillator power amplifier system consisting of a DBR laser and a tapered amplifier has been realised. A maximum output power of 7.4 W in single-longitudinal mode operation with a narrow spectral linewidth and a sidemode suppression ratio better than 40 dB is presented.     

Demonstration of high-energy 2 omega (526.5 nm) operation on the National Ignition Facility Laser System

A single beamline of the National Ignition Facility (NIF) has been operated at a wavelength of 526.5 nm (2 omega) by frequency converting the fundamental 1053 nm (1 omega) wavelength with an 18.2 mm thick type-I potassium dihydrogen phosphate (KDP) second-harmonic generator (SHG) crystal. Second-harmonic energies of up to 17.9 kJ were measured at the final optics focal plane with a conversion efficiency of 82%. For a similarly configured 192-beam NIF, this scales to a total 2 omega energy of 3.4 MJ full NIF equivalent (FNE).     

Fundamental-Lateral Mode Stabilized High-Power Ridge-Waveguide Lasers With a Low Beam Divergence

We compare ridge-waveguide lasers with trench widths of 5 and 20 mum. The emission wavelength is around 1064 nm and the ridge width is 5 m. The maximum output power exceeds 2 W. The 5-mum trench-width device exhibits a much more stable lateral far-field. The full-width at half-maximum of the vertical far-field profile is only 15deg due to a super-large optical cavity.     

High pak power femtosecond pulses from modelocked semiconductor laser in external cavity

The generation of high peak power femtosecond pulses from an all semiconductor laser system is demonstrated. The system is based on a passively modelocked two-section laser diode in an external cavity, a tapered amplifier and a compact external pulse compressor. Pulse durations are achieved below 600 fs with an average optical power above 500 mW at a repetition rate of 330 MHz. This corresponds to a peak power of 2.5 kW, which is the highest value reported for an all semiconductor ultrafast laser system so far.     

12W high-brightness single-frequency DBR tapered diode laser

A distributed Bragg reflector (DBR) tapered diode laser with a record optical output power of 12 W and a conversion efficiency of about 44% is presented. The device has a sixth-order surface grating and shows single longitudinal mode emission at 979 nm as well as a nearly diffraction limited beam. At 11.4 W the laser has a lateral beam propagation factor of M ² _1/ e ²=1.1 with 72% of the power in the central lobe.     

Tunable high-power narrow-spectrum external-cavity diode laser at 675 nm as a pump source for UV generation

High-power narrow-spectrum diode laser systems based on tapered gain media in an external cavity are demonstrated at 675 nm. Two 2 mm long amplifiers are used, one with a 500 μm long ridge-waveguide section (device A), the other with a 750 μm long ridge-waveguide section (device B). Laser system A based on device A is tunable from 663 to 684 nm with output power higher than 0.55 W in the tuning range; as high as 1.25 W output power is obtained at 675.34 nm. The emission spectral bandwidth is less than 0.05 nm throughout the tuning range, and the beam quality factor M(2) is 2.07 at an output power of 1.0 W. Laser system B based on device B is tunable from 666 to 685 nm. As high as 1.05 W output power is obtained around 675.67 nm. The emission spectral bandwidth is less than 0.07 nm throughout the tuning range, and the beam quality factor M(2) is 1.13 at an output power of 0.93 W. Laser system B is used as a pump source for the generation of 337.6 nm UV light by single-pass frequency doubling in a bismuth triborate (BIBO) crystal. An output power of 109 μW UV light, corresponding to a conversion efficiency of 0.026% W(-1), is attained.