Efficient second-harmonic generation using a semiconductor tapered amplifier in a coupled ring-resonator geometry.

A new approach for efficient second-harmonic generation using diode lasers is presented. The experimental setup is based on a tapered amplifier operated in a ring resonator that is coupled to a miniaturized enhancement ring resonator containing a periodically poled lithium niobate crystal. Frequency locking of the diode laser emission to the resonance frequency of the enhancement cavity is realized purely optically, resulting in stable, single-frequency operation. Blue light at 488 nm with an output power of 310 mW is generated with an optical-to-optical conversion efficiency of 18%.

Stripe-array diode-laser in an off-axis external cavity: theory and experiment.

Stripe-array diode lasers naturally operate in an anti-phase supermode. This produces a sharp double lobe far field at angles +/-alpha depending on the period of the array. In this paper a 40 emitter gain guided stripe-array laterally coupled by off-axis filtered feedback is investigated experimentally and numerically. We predict theoretically and confirm experimentally that at doubled feedback angle 2alpha a stable higher order supermode exists with twice the number of emitters per array period. The theoretical model is based on time domain traveling wave equations for optical fields coupled to the carrier density equation taking into account diffusion of carriers. Feedback from the external reflector is modeled using Fresnel integration.

100 mW high efficient single pass SHG at 488 nm of a single broad area laser diode with external cavity using a PPLN waveguide crystal.

A frequency stabilized single broad area laser in a V-shaped external cavity is used for Second Harmonic Generation (SHG) in a waveguide channel with dimensions of 3 mum x 5 mum x 10 mm of a PPMgO: LN crystal. A maximum coupling efficiency of 63% could be obtained. An optical output power of 100.4 mW of visible light at 488 nm could be generated with 265 mW of coupled infrared light. This results in a single pass conversion efficiency of 37.8%. No photorefractive damage or saturation effects were observed.

Tuning high-power laser diodes with as much as 0.38 W of power and M(2) = 1.2 over a range of 32 nm with 3-GHz bandwidth.

Gain-guided diode lasers usually have emission wavelengths determined by the manufacturing process, with typically 0.5-1-nm bandwidth. Furthermore, their beam quality is rather poor. We show that external cavities allow for tunable narrow-bandwidth operation of gain-guided diode lasers. At the same time the beam quality is drastically improved; almost diffraction-limited light of more than 200 mW has been achieved over the whole tuning range from 910 to 942 nm with narrow bandwidth.