Generation of coherent terahertz pulses in ruby at room temperature

Abstract

We have shown that a coherently driven solid state medium can potentially produce strong controllable short pulses of THz radiation. The high efficiency of the technique is based on excitation of maximal THz coherence by applying resonant optical pulses to the medium. The excited coherence in the medium is connected to macroscopic polarization coupled to THz radiation. We have performed detailed simulations by solving the coupled density matrix and Maxwell equations. By using a simple V -type energy scheme for ruby, we have demonstrated that the energy of generated THz pulses ranges from hundreds of pico-Joules to nano-Joules at room temperature and micro-Joules at liquid helium temperature, with pulse durations from picoseconds to tens of nanoseconds. We have also suggested a coherent ruby source that lases on two optical wavelengths and simultaneously generates THz radiation. We discussed also possibilities of extension of the technique to different solid-state materials.

Interaction mechanism of a terahertz wave generator using a field emission cathode

“…Figure 5 shows our monitored average power per cathode area for the two cases. [24][25][26][27][28] In comparison, an efficiency of 3%-4% is relatively high and this motivates us to further study the interaction mechanisms. It is difficult to separate the component of terahertz waves from the monitored output power in the time domain, so that the results of the two cases are similar.…”

Tunability of terahertz random lasers with temperature based on superconducting materials

“…A and E, respectively, and the frequency between them is 29 cm À1 . 25,43 By optical pumping the ruby grain from 4 A 2 state to 2…”

Excitation of atomic coherence at XUV transition enhanced by tunneling in an electric field for X-ray generation

“…For example, lasing without population inversion (LWI) [18,19] and electromagnetically induced transparency (EIT) [20] have been demonstrated [21,22] in coherently driven media. These unusual properties hold promise for the generation of electromagnetic radiation of different frequencies [23][24][25][26][27][28] ranging from IR to UV, X-ray [2,29], and gamma-rays [30]. Enhancement of coherent Raman scattering via maximal coherence has been demonstrated experimentally [31].…”