Compact Vertically Stacked Master Oscillator Power Amplifier Based on Grating Coupled Laser Diodes

A new design of hybrid master oscillator power amplifier (MOPA) has been proposed and realized by vertically stacking laser diodes with optical coupling provided by identical in-plane integrated gratings. Low beam divergence, large emitting and input areas of the grating coupled devices simplify the assembling technique over the fabrication of MOPA devices based on edge-emitting laser diodes. The master oscillator also incorporates a dual-grating reflector providing a wavelength-selective feedback resulting in a narrow emission spectrum of 0.2 nm at a wavelength of 975.4 nm. The power amplifier is a tapered chip with two integrated grating couplers. The operational characteristics of the MOPA were evaluated in the pulse regime demonstrating an output peak power of 32 W with a total amplification factor of 9.3dB