Widely tunable multimode-interference based coupled cavity laser with integrated interferometer.

We present a simple to process tunable laser, fabricated in a low-cost generic fabrication process and based on two coupled Fabry-Perot cavities. The complex coupling coefficients of the coupling element are analytically derived from a 3×3 MMI using coupled mode theory and chosen to maximize the SMSR during lasing operation. Additionally, one of the cavities contains a reflective interferometer, which acts as coarse wavelength selector. This interferometer is derived from a Michelson Interferometer, by replacing the two independent mirrors with our optimized coupling element, leading to a doubled Free Spectral Range. As a result, we obtained a tuning range of 26 nm with potential for beyond 40 nm, a SMSR larger than 40 dB and fiber coupled power up to 9 dBm.