High-stability LD-pumped solid state laser

In high power laser systems, the stability of the seed laser is vitally important. This paper focuses on work undertaken to design and make a high stable LD pumped solid state seed laser which had the advantage of being all solid state, compact, easy to manufacture and low cost. The laser was composed of two parts. One part was a LD pumped 0.5 mm thick Nd:YLF laser system in which the instability was around +/- 6% (3(sigma) ). The other part was a close-looped laser power control system using external cavity power feedback. Using an electro-optic modulator, a 1 X 2 optical fiber splitter and a signal processing circuit, we successfully realized the high stable LD pumped Nd:YLF laser in which the instability of laser output power was lower than +/- 0.2%/hour (3(sigma) ). A digital PID control method was used in which the control frequency was 40 kHz. We obtained 3 mW of high stability laser power through the optical fiber.