Arsenic Trisulfide on Lithium Niobate Waveguides for Nonlinear Infrared Optics

Arsenic trisulfide (As_(2)S_(3)) waveguides on lithium niobate (LiNbO_(3)) substrate have a wide variety of applications in both near-infrared (near-IR) and mid-infrared (mid-IR). As an amorphous material, As_(2)S_(3) has large transmission range (0.2-11?m) and high nonlinear refractive index (n_(2)=3?10^(-18) m^(2)/W), which can be utilized to nonlinear infrared optics. Meanwhile, as a birefringence material, LiNbO_(3) is an attractive substrate to integrate with As_(2)S_(3) waveguides by semiconductor fabrication techniques, due to its lower refractive index and large transmission range (0.42-5.2 ?m).

Since low loss As_(2)S_(3)-on-LiNbO_(3) waveguides have been developed, it is a good time to exploit its applications in mid-IR wavelength. We illustrate the application of As_(2)S_(3)-on-LiNbO_(3) waveguides in four-wave-mixing (FWM), which can generate 3.03 ?m mid-IR light by a 1.55 ?m near-IR signal source and a strong 2.05 ?m pump source. When pump power intensity is 0.1 GW/cm^(2), the largest parametric conversion efficiency at 3.03 ?m is -8 dB. On the other hand, since mid-IR detectors are limited in terms of noise performance, we also provide an excellent solution with our As_(2)S_(3)-on-LiNbO_(3) waveguides, which largely improve the electrical signal-to-noise ratio (eSNR) by converting mid-IR signals to near-IR wavelengths. Therefore, state-of-the-art near-IR commercial detectors can be used to detector mid-IR signals indirectly.

In order to characterize our different types of optical devices in near-IR and mid-IR, we build a measurement system using optical low-coherence interferometry (OLCI) and Fourier transform spectroscopy techniques. The group delay of the device-under-test (DUT) can be achieved.