Facilities

An external‐cavity diode laser for 1550‐nm wavelength is reported with ultra‐low noise, high power coupled to a fiber, and fast tunability. These characteristics enable the generation of an optical frequency comb in a silica micro‐resonator with a single‐soliton state. Neither an optical amplifier nor a modulator is used in the experiment. This demonstration greatly simplifies the soliton generation setup and represents a significant step forward to a fully integrated soliton comb system. 

Ge-on-Si low-loss waveguides and 7 × 8 arrayed waveguide gratings (AWGs) are presented for operation near 4.7 µm wavelength. Propagation loss in the range of 3 dB/cm for fully etched waveguides and 1 dB/cm for shallow-etched waveguides is reported. 200 GHz AWGs in a 7 × 8 configuration with various waveguide aperture widths and etch depths are designed and characterized. For fully etched AWGs, the insertion loss values as low as −2.34 and 3 dB mean cross talk of −29.63 dB are achieved. The shallow-etched AWG has an insertion loss of −1.52 dB and crosstalk of −28 dB.