J. Fricke

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-power 980-nm DFB RW lasers with a narrow vertical far field

We compare 980-nm distributed-feedback ridge-waveguide lasers having cavity lengths of 1.5 and 3 mm. The maximum single-mode output powers are 500 and 700 mW, respectively. The full-width at half-maximum of the vertical far-field profile is only 22/spl deg/ due to a superlarge optical cavity.

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 980-nm Broad-Area Lasers Spectrally Stabilized by Surface Bragg Gratings

We report on broad-area distributed Bragg reflector (DBR) lasers with a stripe width of 90 ¿m providing up to 14-W optical power and 50% maximum conversion efficiency. Ninety-five percent of the power is included within a wavelength range of less than 1 nm. The wavelength shift between threshold and the maximum output power is less than 3.5 nm. The wavelength stabilization is achieved with a 500-¿m -long DBR containing a sixth-order Bragg grating defined by i-line wafer stepper lithography and fabricated by reactive ion etching.

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

Suppression of Higher-Order Lateral Modes in Broad-Area Diode Lasers by Resonant Anti-Guiding

For a maximum fiber-coupled power, high power broad-area diode lasers must operate with a small lateral far-field divergence at high continuous wave (CW) powers. However, these structures are laterally multi-moded, with a low beam quality and wide emission angles. We present a new approach to suppress higher-order lateral modes based on an anti-guiding layer with a high refractive index inserted at the edges of the active stripe. Simulations of planar waveguides containing germanium layers reveal that strong mode-coupling effects occur. These are found to vary as a function of the thickness of the inserted layer. By embedding the germanium layer in the outer region of a ridge-waveguide, the mode coupling effects result in a reduction of the modal gain of higher-order lateral modes. The lateral far-field divergence of fabricated 90- μm stripe lasers emitting at 980 nm and containing such an anti-guiding layer is narrowed by 3° at a CW output power of 10 W.

High-Power Distributed Feedback Lasers With Surface Gratings

We present the results for high-power broad-area distributed feedback lasers with surface gratings of 80th, 135th, and 270th Bragg orders. A maximum output power of 11 W for a laser with 80th order grating, emitting around 976 nm with a spectral width <; 1 nm has been achieved. Similar narrow linewidth operation occurs for devices with 135th Bragg order from 7- to 11-W output power. The technological approach to fabricating these devices based on stepper lithography and reactive ion etching is described.

High Brightness, Narrow Bandwidth DBR Diode Lasers at 1120 nm

In this letter, we report on monolithic distributed Bragg reflector ridge waveguide diode lasers. The lasers feature highly strained InGaAs quantum wells and fifth order surface gratings for a stabilized emission wavelength ~1120 nm. Output powers up to 1 W and a maximum conversion efficiency of ~34% were achieved in a spatial and spectral single-mode. In a preliminary reliability test, at 0.4 W a lifetime of could be demonstrated. Therefore, the laser sources should allow for an efficient non-linear frequency doubling to 560 nm.

Tensile-strained GaAsP-AlGaAs laser diodes for reliable 1.2-W continuous-wave operation at 735 nm

Tensile-strained GaAsP quantum wells embedded in AlGaAs large optical cavity structure were investigated at an emission wavelength of 735 nm. 1.2-W continuous-wave operation for 100-/spl mu/m stripe width diode lasers over 1000 h is reported. Experiments with different stripe widths showed a high stability at an output power of 12-mW//spl mu/m stripe widths with degradation rates below 5/spl middot/10/sup -5/ h/sup -1/, i.e., lifetimes larger than 5000 h could be expected.

Fundamental-lateral mode stabilized high-power ridge-waveguide lasers

This paper investigates the impact of lateral radiation losses in ridge waveguide (RW) lasers emitting around 1064 nm is investigated. The RWs are fabricated by dry etching of pairs of trenches with widths between 2.5 and 20 μm into the epitaxial layer structure in order to define the RWs.