Blue-Green Laser System for Underwater Ranging

Investigation into the use of laser sources for underwater applications has been underway for many years. To date, there is still need for a laser system which satisfies the requirements of wavelength, pulse width, average power and repetition frequency while simultaneously meeting the constraints of size, weight, efficiency, reliability, and cost. The system proposed by LPC promises quantum leaps in performance over currently existing technologies. The proposed system, based on a highly efficient, diode-pumped, frequency doubled solid state laser employing a novel cavity configuration, will provide a superior match to the underwater transmission window than Nd:YAG, while still maintaining a higher efficiency and producing 75% less waste heat. It follows that this system can generate a higher effective output power and energy in a smaller package. To overcome fundamental limitations in material properties and generate pulses short enough for high resolution, long range capabilities, our system design utilizes a Q-switched, cavity dumped oscillator followed by a power amplifier in a multi-pass configuration. Preliminary research has revealed that a diode-pumped master oscillator/power amplifier combination, frequency doubled to the blue-green, is the optimum choice for air-to-sea detection, ranging, imaging, and other underwater applications.