Lab is dedicated to the phase measurement of light-wave circuits. A novel phase sensitive set-up based on a free space Mach-Zehnder interferometer allows measuring simultaneously the transmitted intensity and phase shift of generic optical integrated circuits. In this way, the transmitted intensity are completed by the knowledge of the phase. The interferometer allows us to perform both characterization measurements in the linear regime and Pump and Probe measurements in the non-linear one. The possibility to detect the signal response by means of a Lock-in Amplifier not only decreases the signal to noise ratio but also allows filtering the Probe from the Pump signal even if they have the same wavelengths. Systematic and stable measurements are ensured by a full remote control of the interferometer and by enclosing it into a box. A detailed description of the optical set-up is reported in the ref. [1].  

Examples of characterized samples are straight waveguides, single-/multi-mode optical resonators plane/vertical coupled to a bus waveguide, space sequence of optical resonators. Pump and Probe measurements are performed to study: the optical bistability in resonators and the quantum fluid of light in cavity-less circuits.  

The equipment of the lab is the following:

Light Sources: Tunable SC band laser (1475-1575nm), Tunable OL band laser (1260-1650nm), Erbium-doped fiber amplifier (EDFA) 5W (1535-1565nm).

Detectors: 1x Near-IR Optical Spectrum Analyzers (OSA), 2x Ge IR detectors, InGaAs IR Camera, Visible Camera.

Fiber based devices: 1x IR Variable Optical Attenuators (VOA), 2x Optical Isolators C band, 2x IR polarization controllers, 1x 50:50 Fiber optic coupler.

General Optical/Optomechanical Components: 1x Optical Table, 2x Three Axis positioners with piezo-electric controllers, 3x Chopper Wheels.

Electronics: 1x Function generators, 1x Power sources, 2x Lock-in Amplifier, 2x DAQ devices, 5x stepper motors, All the devices are controlled and monitored with a computer.

References:

[1] F. Turri, S. Biasi, F. Ramiro Manzano and L. Pavesi, "A Free-Space Interferometer for Phase-Delay Measurements in Integrated Optical Devices in Degenerate Pump-and-Probe Experiments," in IEEE Transactions on Instrumentation and Measurement, vol. 67, no. 12, pp. 2863-2871, Dec. 2018.