Theoretical calculation and experimental demonstration indicate that there is an optimal position near the zero optical bias point in a crossed polarizer electro-optic sampling geometry. At this position, free-space electro-optic sampling with a ZnTe sensor crystal has the largest modulation depth for the detection of a weak (THz) modulated signal on a strong laser background. Electro-optic sampling of THz pulses with a modulation depth of 9% and a signal-to-noise ratio better than 50 000:1 is demonstrated.

In this letter, terahertz (THz) pulse measurements with a chirped probe pulse are analyzed. The method of stationary phase is used to explore the relation between the temporal waveform of an input THz pulse and spectral distribution of an output probe pulse on a detector array. The dependence of the temporal resolution on the chirp rate, the spectrum of the chirped probe beam, and the spectral resolution of the spectrometer is discussed. We confirm that the temporal resolution of the chirped pulse technique is equal to the square root of the product of the original unchirped probe pulse duration and the chirped pulse duration.

Antennas based on commercially available GaAs as a photoconductor with a subnanosecond photocarrier lifetime have been used to detect subpicosecond free-space electromagnetic radiation (THz pulses). At low optical gating intensities (≤1 mW/100 μm2), GaAs based antennas exhibit a higher responsivity and signal-to-noise ratio than typical antennas based on radiation-damaged silicon-on-sapphire.

Articles you may be interested inResearch on the magneto-optic current sensor for high-current pulses Rev. Sci. Instrum. 79, 083106 (2008); 10.1063/1.2968200 Sensitive magneto-optical sensors for visualization of magnetic fields using garnet films of specific orientations J. Appl. Phys. 92, 6484 (2002); 10.1063/1.1516839 Magneto-optical observation of the latchup effect in CMOS ICs induced by uniform and local irradiation

We report the recent measurement and analysis of the transmitted and pseudoreflected optically induced terahertz (THz) beams emitted from a semiconductor wafer under femtosecond laser illumination, where the static electric field is either parallel or perpendicular to the surface. In general, the amplitude of the transmitted THz field is different from that of pseudoreflected THz field, except at the Brewster angle.