Development of an 813-nm Tm-doped ZBLAN fiber amplifier for the Sr optical lattice clock

摘要

The Sr Optical Lattice Clock (OLC) was developed by Prof. Katori in 2005 [1], and also research on it has been conducted as major candidates for the next generation optical frequency standards. The light sources for Sr-OLC is required to be single tunable frequency, long-term stability, portable, and high beam quality. One of the key technologies for improving OLC is a high power trapping laser for collecting larger number of ions. Requierments of the trapping laser are wavelength at 813nm, linewidth of less than 1 MHz, and output power of higher than 1 W. In the current Sr-OLC, Ti: Sapphire lasers or semiconductor tapered amplifiers are employed for the trapping laser. However, they have following disadvantages of its lager-size, low beam quality and difficulty in stable long-term operation. In order to solve these problems, we have developed Master-Oscillator Fiber Power Amplifier (MOFPA) by using a Tm-doped ZBLAN fiber amplifier.