High-power distributed-feedback tapered master-oscillator power amplifiers emitting at 1064 nm

摘要

In this work, we investigate experimentally optimized monolithic distributed-feedback (DFB) tapered master-oscillator power amplifiers (MOPA). The devices consist of three autonomously driven sections: a 1 mm long DFB ridgewaveguide (RW) laser, a 1 mm long RW pre-amplifier and 2 mm or 4 mm long tapered amplifiers. The ridge width and the full taper angle are 5 μm and 6°, respectively. Both laser facets are anti-reflection coated. The second order Bragg gratings in the DFB laser were realized by holographic photolithography, wet-chemical etching and a two-step epitaxy. The DFB tapered MOPAs emit nearly diffraction limited spectral single mode CW radiation at 1064 nm. The 6 mm long devices provide an optical power of about 12 W at DFB laser, pre-amplifier and tapered amplifier currents of 150 mA, 400 mA and 18 A, respectively. The 4 mm long devices generate more than 4 W at a tapered amplifier current of 7 A. The spectral drift versus output power is below 50 pm/W.