B. Sumpf

5-W DBR Tapered Lasers Emitting at 1060 nm With a Narrow Spectral Linewidth and a Nearly Diffraction-Limited Beam Quality

Distributed Bragg reflector tapered lasers emitting at a wavelength of about 1060 nm were realized. The expitaxial layer structure leads to a vertical far-field angle of 15deg (full-width at half-maximum). The devices with a total length of 4 mm consist of 2-mm-long ridge waveguide and tapered sections. The input currents to both sections can be independently controlled. The laser reached 5-W output power with a narrow spectral linewidth below 40 pm (95% power) and a nearly diffraction-limited beam quality.

High-power 808-nm tapered diode lasers with nearly diffraction-limited beam quality of M/sup 2/=1.9 at P=4.4 W

High-power 808-nm tapered diode lasers mounted as single emitters with very good brightness were manufactured and analyzed. The beam propagation ratio M² is 1.9 at 4.4 W; a very low beam propagation ratio M² of 1.3 is achieved at 3.9 W. At 808 nm, the high brightness of 460 MWmiddotcm^-2 sr^-1 never reported before is a step forward toward new applications of tapered diode lasers

Nearly Diffraction-Limited Tapered Lasers at 675 nm With 1-W Output Power and Conversion Efficiencies Above 30%

High brightness, highly efficient tapered lasers emitting around 675 nm have been developed. The devices have a 500- μm-long straight section and a 1500-μm -long tapered section with a flare angle of 3°. At a temperature of 25°C and a current of 1.5 A, the lasers emit an output power of nearly 1.2 W. The maximum conversion efficiency of 31% is reached at an output power of 1 W. The emitted beam is nearly diffraction-limited with a beam propagation ratio (second moments) of 2.2.

Narrow Linewidth of 633-nm DBR Ridge-Waveguide Lasers

Compact laser sources with long coherence lengths in the visible spectral region are sought for many applications. This letter presents distributed-Bragg-reflector (DBR) ridge-waveguide (RW) lasers with an emission wavelength at 633 nm and an optical output power >20 mW. The DBR-RW lasers exhibit a technical linewidth at full width at half maximum of ~1 MHz. The emission line can be tuned via current and temperature >200 GHz. At 14 mW, the lasers show a preliminary lifetime 4000 h.

CW technique for measurement of linewidth enhancement factor: application to 735-nm tensile-strained GaAsP quantum-well lasers

We present a procedure for determining the linewidth enhancement factor (/spl alpha/ parameter) in semiconductor lasers under continuous-wave (CW) operation. It is based on the measurement of the amplified spontaneous emission spectra, with a proper correction of thermal effects. The method is applied to 735-nm tensile strained GaAsP-AlGaAs quantum-well lasers and it is validated by comparing CW results, after correcting thermal effects, with pulsed measurements. The results show a low value of the /spl alpha/ parameter attributed to the tensile strain.

Highly efficient single-pass sum frequency generation by cascaded nonlinear crystals.

The cascading of nonlinear crystals has been established as a simple method to greatly increase the conversion efficiency of single-pass second-harmonic generation compared to a single-crystal scheme. Here, we show for the first time that the technique can be extended to sum frequency generation, despite differences in the phase relations of the involved fields. An unprecedented 5.5 W of continuous-wave diffraction-limited green light is generated from the single-pass sum frequency mixing of two diode lasers in two periodically poled nonlinear crystals (conversion efficiency 50%). The technique is generally applicable and can be applied to any combination of fundamental wavelengths and nonlinear crystals.

Miniaturized Tunable External Cavity Diode Laser with Single-Mode Operation and a Narrow Linewidth at 633 nm

A miniaturized, standalone tunable semiconductor laser module operating at a wavelength of 633 nm with a footprint as small as 10 mm × 5 mm is presented. The module is based on an external cavity diode laser system with no moving parts and features a frequency tuning range of 25 GHz with a spectral linewidth of approximately 10 MHz. An output power of 10 mW within a nearly diffraction-limited beam is demonstrated. The electrical power consumption, including thermal management, is around 0.7 W.

High-Power Pulse Generation in GHz Range With 1064-nm DBR Tapered Laser

For high-power pulse generation at 1060-nm, distributed Bragg reflector tapered lasers were investigated. The lasers consist of a tapered section, a ridge waveguide (RW) absorber section and a passive grating section with a sixth-order surface grating. For the generation of short optical pulses, the tapered section was biased with a dc-current and the RW absorber section was modulated with a 1-GHz sinusoidal current. At a repetition rate of 1 GHz-6.3 W optical pulses with 74-ps full-width at half-maximum and a small spectral widths of 50 pm were generated.

Widely Tunable High-Power Tapered Diode Laser at 1060 nm

We report a large tuning range from 1018 to 1093 nm from a InGaAs single quantum-well 1060-nm external cavity tapered diode laser. More than 2.5-W output power has been achieved. The tuning range is to our knowledge the widest obtained from a high-power InGaAs single quantum-well tapered laser operating around 1060 nm. The light emitted by the laser has a nearly diffraction limited beam quality and a narrow linewidth of less than 6 pm everywhere in the tuning range.

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.