Laser pulse generation has emphasized either minimum pulse duration, typically to maximize peak power, (mode-locked pulses), or maximum energy per pulse (q-switched solid state lasers). Both of these approaches have pushed pulse durations well below 100 ns. Modern broad stripe diode lasers with relaxation times in the nanoseconds can be modulated to produce the required pulse durations and energies with simple modulation of the drive current and mimimal risk to the diodes themselves. However, diode lasers capable of achieving the power levels required emit light outside the spectral region of interest have notoriously poor beam quality as well as substantially greater divergence angles than required for ship self-defense applications. During the course of this Phase I program, a novel technique for spatial and spectral conversion of diode laser pump light into the wavelengths and divergence angles of interest will be designed and analyzed. A proof of concept will be demonstrated using a Nd:YAG laser as a simulated diode laser pump. The final report will include preliminary design parameters for scaling up the proof of concept for a Phase II prototype to achieve 50 mJ 200 ns pulses at 1 kHz repetition rates in each of the desired wavelength regions.
Keywords: Fiber Lasers, Raman, Visible, Nonlinear Optics
