Detection of terahertz radiation from longitudinal optical phonon–plasmon coupling modes in InSb film using an ultrabroadband photoconductive antenna

Abstract

Terahertz radiation from longitudinal optical (LO) phonon–plasmon coupling modes in InSb films is observed using an ultrafast photoconductive antenna detector. We demonstrate a response frequency of up to 7 THz for a low-temperature-grown GaAs-based photoconductive antenna gated with 25 fs laser pulses. It is found that the emission frequencies of the coupling modes are dependent only on the residual carrier density, not on the excitation carrier density. It is also found that the LO phonon–plasmon oscillations in semiconductors can serve as an efficient THz source.

Two-fluid hydrodynamic model for semiconductors

“…A third kind of excitation especially found in nonelemental semiconductors is optical phonons. These resonances of the lattice may couple to the plasmons if they are in the same frequency range, and this interaction has been studied for both InSb [74,75] and GaAs [76,77]. It should also be mentioned that for InSb, in particular, a charge-carrier depleted region known as the space-charge layer may exist close to the surface which would be relevant for the optical properties.…”

Terahertz radiation induced by coherent phonon generation via impulsive stimulated Raman scattering in paratellurite

“…Interesting phenomena based upon coherent phonon generation were previously reported by a variety of experiments [2,3], for examples, ultrafast control of coherent phonons by using a pair of femtosecond laser pulses with an appropriate interval [4,5], the observation of vibronic wavepackets in time domain [6], and the generation of the frequency comb over 100 THz [7]. Furthermore, it was demonstrated that narrowband terahertz waves can be emitted by coherent phonon generation in various kinds of semiconductors such as Te [8,9], GaAs [10], GaAs/AlAs multiple quantum wells [11], (Pb,Cd)Te [12], InSb [13][14][15], and Li(In,Ga)(S,Se) [16].…”

Photoconductive Emission and Detection of Terahertz Pulsed Radiation Using Semiconductors and Semiconductor Devices

“…Gu et al [42] observed that there is a significant contribution to the THz emission from InSb and InAs due to the nonlinear optical rectification process even for relatively low pump power values. For an n-InAs (111) surface, the optical rectification contribution amounts to about 40 % of the total THz emission for a low excitation intensity of~60 MW/cm 2 of 800-nm fs laser pulses.…”