High-power solid-state laser targets niche applications

Researchers at Laser Power Corporation (San Diego, CA) have constructed a 130-mW, 1550-nm solid-state laser source intended for use in sensors and optical generation of ultrastable signals. The device was fabricated using a 1-W, 980-nm indium gallium arsenide (InGaAs) pump diode laser and a laser cavity consisting of an erbium ytterbium codoped phosphate glass disk, a lithium niobate phase modulator, and a Polarcor Fabry-Perot etalon. The 1-mm-thick modulator, 1-mm-thick glass disk, and 100-µm-thick etalon were bonded together to form a single structure. The modulator enabled tuning of the laser wavelength and chirping of the approximately 22-kHz linewidth to defeat stimulated Brillouin scattering. It also acted as a heat spreader, reducing peak temperatures and stresses in the cavity by about 50%, thereby enabling high pump- and output-power values. The etalon served to fix the polarization state of the laser output. An optoelectronic feedback loop reduced relative intensity noise by as much as 35 dB. The size of the entire device, including additional optical elements, was 0.5 x 1.5 x 2.0 in.