Exploiting the Optical Quadratic Nonlinearity of Zinc-Blende Semiconductors for Guided-Wave Terahertz Generation: A Material Comparison

Abstract

We present a detailed analysis and comparison of dielectric waveguides made of CdTe, GaP, GaAs and InP for modal phase matched optical difference frequency generation (DFG) in the terahertz domain. From the form of the DFG equations, we derived the definition of a very general figure of merit (FOM). In turn, this FOM enabled us to compare different configurations, by taking into account linear and nonlinear susceptibility dispersion, terahertz absorption, and a rigorous evaluation of the waveguide modes properties. The most efficient waveguides found with this procedure are predicted to approach the quantum efficiency limit with input optical power in the order of kWs.

Measurements of Silicon Photomultipliers Responsivity in Continuous Wave Regime

“…On the other hand, features like their high gain, fast timing response with low fluctuation and high responsivity to extremely low photon fluxes [14] could open up new SiPMs applications in a variety of fields, such as very low power measurements (less than 1 pW) [23]. SiPMs performances in photon counting mode have been investigated in several papers, using picosecond pulsed lasers [1]- [3], [8]- [14], [24]. Optical characterization performed via continuous wave (CW) sources has seldom been reported [23], [25] even though this kind of excitation seems to be very useful in several applications [22], [23], [26]- [30].…”

Silicon Photomultipliers Signal-to-Noise Ratio in the Continuous Wave Regime

“…High gain, excellent timing properties, and insensitivity to magnetic fields could guarantee new SiPM applications in several fields. At the present time, SiPMs are mainly employed in photon counting mode, in conjunction with pulsed lasers [1]- [3], [10]- [16], [21], [22] and, therefore, the dark noise is the main noise source. However, SiPMs can be used in the continuous wave (CW) regime in several applications, such as very low power measurements (less than 1 pW) [23], as disposable sensors in immunoassay tests [24] and, above all, in CW near-infrared spectroscopy systems [25]- [32].…”

Optical turbulence measurements and channel modeling of an indoor Free Space Optics link

“…Thanks to the most recent laser technologies, high-power sources at the most important wavelengths for free space communications (i.e., 850 and 1550 nm) are nowadays available on the market. In addition, new communication windows for FSO links can be exploited using nonlinear optics techniques which are employed to generate coherent emission at a wide range of wavelengths, from visible to THz [5][6][7]. Nonetheless, in the most widely employed free space optical communication windows, the modulated optical beam, while propagating in the atmosphere, can be affected by unfavorable atmospheric conditions (e.g., rain, fog, snow, smog, scattering, etc.)…”