DescriptionWidely tunable, high coherence diode lasers have found a wide range of important applications, from terrestrial ones, such as fiber-optic communications or optical sensing, to applications in space, for instance in atomic clocks. Monolithic diode lasers for such tasks, i.e., distributed feedback (DFB) lasers and distributed Bragg reflector (DBR) lasers, approach their limits since they typically show either a small tuning range or low coherence with large spectral linewidths at the MHz level. Hybrid lasers, in contrast, are free from these limits. In such lasers, the gain from a semiconductor optical amplifier chip is receiving spectrally filtered feedback from a second chip fabricated from dielectric material. The second chip carries an integrated-optical waveguide circuit with which highly selective filtering and a long photon lifetime can be realized.
Here we report the realization of a wavelength-tunable hybrid diode laser that offers about 80 nm tuning range and a high output power (10-20 mW). In order to impose a small quantum (Schawlow-Townes) linewidth, we equip the laser diode with a low-loss Si3N4 waveguide circuits (TripleXTM) of a significant roundtrip optical length (50 cm on a chip). The resulting lowest quantum linewidth observed is 290 Hertz. The demonstrated narrow quantum linewidth is far below that of any reported chip-based and tunable hybrid laser and thereby may mark a new paradigm in employing semiconductor lasers for providing light with ultra-high coherence in an application relevant format.
|Period||12 Dec 2017|
|Event title||International MicroNanoConference, iMNC 2017|
|Degree of Recognition||International|