Widely tunable near-IR monolithic coherent source

The InP and GaAs platforms, well known for their mature laser-diode technology, allow for efficient optical frequency conversion on chip thanks to their strong quadratic nonlinearity and broad transparency range. Based on... [ view full abstract ]

The InP and GaAs platforms, well known for their mature laser-diode technology, allow for efficient optical frequency conversion on chip thanks to their strong quadratic nonlinearity and broad transparency range. Based on these features, we report on the design and preliminary characterization of a monolithic widely tunable near-IR parametric source.
Two spontaneous-parametric-down-conversion (SPDC) sources are studied. The first one relies either on a GaAs/AlGaAs laser diode operating as a pump at 1 µm or on an InGaAsP/InP diode with laser emission at 1.55 µm, with intracavity SPDC from 1.8 to 2.3 µm or around 3 µm, respectively. In the second one, two superposed cavities for laser emission and SPDC are coupled through a vertical tapered coupler. These designs are accompanied by a characterization of GaxIn1-xAsyP1-y refractive index in the near-IR range up to 3 µm, where this alloy has never been studied despite its common use in the telecom range. The material index is determined with a precision of 0.001 in m-line measurements, extending the wavelength range where it was known and significantly improving the experimental accuracy. Three alloy compositions (y = 0.6, 0.7, 0.75) and three wavelengths (0.55, 2.1 and 3.1 µm) are spanned.
This work is promising for a continuous-wave parametric source on chip, with wavelength tunability up to 500 nm and a peak power of a few milliwatts, enough for out-of-the-lab spectroscopy applications.