GaSb diode lasers tunable around 2.6 <b> <i>μ</i> </b>m using silicon photonics resonators or external diffractive gratings
Samu‐Pekka Ojanen, Jukka Viheriälä, Matteo Cherchi, Nouman Zia, Eero Koivusalo, Pentti Karioja, Mircea Guină
Abstract
We report two tunable diode laser configurations emitting around 2.6 μm, where the gain is provided by a high-gain GaSb-based reflective semiconductor optical amplifier. The lasers are driven in pulsed mode at 20 °C, with a pulse width of 1 μs and 10% duty cycle to minimize heating effects. To demonstrate the broad tuning and high output power capability of the gain chip, an external cavity diode laser configuration based on using a ruled diffraction grating in a Littrow configuration is demonstrated. The laser shows a wide tuning range of 154 nm and a maximum average output power on the order of 10 mW at 2.63 μm, corresponding to a peak power of 100 mW. For a more compact and robust integrated configuration, we consider an extended-cavity laser design where the feedback is provided by a silicon photonics chip acting as a reflector. In particular, the integrated tuning mechanism is based on utilizing the Vernier effect between two thermally tunable micro-ring resonators. In this case, a tuning range of around 70 nm is demonstrated in a compact architecture, with an average power of 1 mW, corresponding to a peak power of 10 mW.