Optical Limiting Using the Two‐Photon Absorption Electrical Modulation Effect in HgCdTe Photodiode

Abstract

The electrical modulation properties of the output intensity of two-photon absorption (TPA) pumping were analyzed in this paper. The frequency dispersion dependence of TPA and the electric field dependence of TPA were calculated using Wherrett theory model and Garcia theory model, respectively. Both predicted a dramatic variation of TPA coefficient which was attributed into the increasing of the transition rate. The output intensity of the laser pulse propagation in the pn junction device was calculated by using function-transfer method. It shows that the output intensity increases nonlinearly with increasing intensity of incident light and eventually reaches saturation. The output saturation intensity depends on the electric field strength; the greater the electric field, the smaller the output intensity. Consequently, the clamped saturation intensity can be controlled by the electric field. The prior advantage of electrical modulation is that the TPA can be varied extremely continuously, thus adjusting the output intensity in a wide range. This large change provides a manipulate method to control steady output intensity of TPA by adjusting electric field.

Spectral broadening induced by intense ultra-short pulse in 4H–SiC crystals

“…Theoretical analysis shows that the two-photon absorption coefficient reaches its maximum when hω/E g is about 0.7, where hω is the photon energy and E g is the bandgap of the semiconductor. [27,28] This value is evaluated to be 0.73 for SI 4H-SiC crystal with bandgap of 3.2 eV under the incident laser at 532 nm. Additionally, previous works showed that electrons in SiC crystals exhibit ultrafast optical response on the fs scale.…”