Phase and Frequency Control of Laser Arrays for Pulse Synthesis

Abstract : A phase locked source, consisting of three beams at fo, fo - 80 MHz, and fo + 80 MHz, was demonstrated. Fast feedback was implemented by an FPGA using a single phase-sensitive detector that recorded the peak power of the waveform. We use feedback from a piezo and current-control of a tapered amplifier. We have demonstrated a pulse train of 4.9 ns pulses at 80 MHz, an order of magnitude reduction in phase noise, and the potential for long-term stability. Additionally, we have explored methods for improving the beam quality of a broad area laser array in a wavelength beam combining cavity. Brightness can be increased by imaging the diffraction-limited fast axis back onto the slow axis, with proper astigmatism compensation. The work has been submitted to the 2014 Conference on Lasers and Electro-Optics (CLEO), presented at the 2013 CLEO, one journal paper published in Optics Express, and another is currently under review for publication in Optics Letters.