The characterization results and analysis from the detection of meso-photonic laser pulses, characterized by zero to tens of photons per pulse, using an inhouse developed detector module based on HgCdTe avalanche photodiodes (APDs) are reported. In this detector module, HgCdTe APDs is hybridized to a specifically developed Si CMOS amplifier circuit with a low input noise and high bandwidth of 400 MHz that is shown to be capable of detecting single photon events at APD gain in excess of 100. The use of a Si CMOS amplifier with a high bandwidth is crucial to detect pulsed signals at high rates. With the present detector, this has enabled to detect temporally distinguishable single photon events up to a record rate of 500 MHz on a single solid-state detector. The capacity of the detector to characterize mesoscopic light states was demonstrated on an input state of an average of l= 1.6 photons using a fitting procedure to extract the timing and amplitude of each pulse. This analog approach to analyze the detection of meso-photonic light is shown to be efficient to estimate the attenuated photon state and to calibrate detector characteristics such as the event detection efficiency (87%), the multiplication gain distribution and corresponding excess noise factor (F = 1.33) and the timing jitter distribution with a full width half maximum of FWHM= 277 ps.
Laser (VCSEL) with a liquid crystal (LC) microcell monolithi-2 cally integrated on its surface for spectral tuning is investigated. 3 Unlike tunable VCSELs integrating a movable membrane, here 4 the physical length of the cavity remains unchanged and only the 5 voltage applied on the LC ensures a refractive index modification 6 for a particular polarization emitted by the VCSEL. This tunable 7 VCSEL operates in CW at room temperature and exhibits 8 more than 23 nm wavelength tuning around 1.55 µm at a 9 maximum applied voltage of 20 V. The measured laser threshold 10 around 6.5 mW is still comparable to VCSEL without 11 LC microcell, a clear indication that the optical losses related 12 the LC are very low. On the other hand, for this first optically 13 pumped device, the lasing characteristics suggest that the LC 14 birefringence is lower than expected. To assess this hypothesis, 15 thermo-optical simulations have been conducted.
Spectral dependence of Lamb coupling constant C is experimentally investigated in an InGaAlAs Quantum Wells active medium. An Optically-Pumped Vertical-External-Cavity Surface-Emitting Laser is designed to sustain the oscillation of two orthogonally polarized modes sharing the same active region while separated in the rest of the cavity. This laser design enables to tune independently the two wavelengths and, at the same time, to apply differential losses in order to extract without any extrapolation the actual coupling constant. C is found to be almost constant and equal to 0.839 ± 0.023 for frequency differences between the two eigenmodes ranging from 45 GHz up to 1.35 THz.
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