Low SWaP miniaturized fiber coupled external cavity diode laser (ECDL) with high optical isolation as plug and play solution

Abstract

We report the latest development of a polarization-maintained fiber-coupled miniaturized external cavity diode laser (ECDL) at 780 nm with a narrow linewidth of less than 100 kHz and optical isolation of higher than 60 dB integrated into a temperature controlled hermetically sealed industrial standard butterfly package. Combined with a fiber-coupled tapered amplifier, this provides a plug and play low SWaP (Size,Weight and Power consumption) “Master Oscillator Power Amplifier”-system, without the need of additional bulky optical free-space components such as optical faraday isolators and time-consuming optical alignment. In addition to robustness and high stability, we were able to combine the narrow linewidth of the external cavity diode laser and the high output power of the amplifier in the footprint of only two butterfly packages. Output powers higher than 25 mW of the seed laser ex-fiber are sufficient to saturate the tapered amplifier to reach optical powers of more than 3 W with high beam quality and integrated beam collimation. The integrated isolators with isolation greater than 60 dB assure a stable operation and no disturbance of the seed laser by the tapered amplifier. Furthermore, we used an additional optical resonator to reduce the linewidth to less than 10 kHz using an electronic stabilization scheme according to the Pound-Drever-Hall technique with electronics provided by TOPTICA Photonics AG.