Mach-Zehnder interferometer (MZI) is a valuable practical tool in many optical science areas. In particular, high-contrast MZI are required for experimental realization of displacement-based quantum receivers that can discriminate weak coherent states of light with the minimum error rate. In this work we study phase modulators of tunable on-chip interferometer on silicon nitride (Si3N4) platform for telecom wavelength (1550 nm) consisting of several MZI. Phase modulators on one of the arms of MZI consists of microheaters and waveguide. Microheaters heat waveguides changing its refractive index due to thermo-optical effect providing a phase shift. We measure the bandwidth of phase modulators and study their operation in pulse mode.
In this work, we study Ga50%Se50-x%Sx crystals (where x = 0, 1.5, 6, 8, 11) as an electrooptic detector of terahertz pulses using probing femtosecond laser radiation with the wavelength of 1.55 μm. It was found that the sample with x = 6 provides the highest detection efficiency. The efficient value of the electrooptic coefficient of GaSe:S crystals is estimated to be about twice higher than those of GaAs in the same conditions.