Theory of guided-wave frequency tripling in the form of coherent Čerenkov radiation: Application to ultraviolet light generation

Abstract

A useful wave-optics solution is derived for the Čerenkov mode calculation of optical third-harmonic signals that are generated in a multilayer planar optical waveguide. With this modal solution, the ultimate performance of the planar-configuration frequency tripler, being phase matched in the form of coherent Čerenkov radiation, is predictable. Numerical results are shown for the third-harmonic ultraviolet light generation in a planar glass waveguide loaded by a polydiacetylene Langmuir–Blodgett deposited thin film. Furthermore, the possibility of pronounced activation of the third-harmonic radiation from a glass waveguide pumped by an intense laser beam is suggested through field calculations based on a laser-induced damage model. In addition, loss analysis that includes both one- and two-photon absorptions is made by means of a phenomenological propagation model using coupled rate equations.

Cascaded Čerenkov third-harmonic generation in random quadratic media

“…10 Among the most interesting emission processes is the socalled Cerenkov scheme, where the phase velocity of the nonlinear polarization wave driven by the fundamental wave is faster than that of the harmonic. [11][12][13][14] Moreover, the observation of conical cascaded Cerenkov-type third harmonic generation in LiNbO 3 was recently reported with artificially disordered square domain lattices. 15 However, up to now, no third harmonic (TH) conical emission was experimentally reported in totally randomized crystals due to the low conversion efficiency.…”

Theoretical analysis of Cherenkov third harmonic generation via two cascaded χ(2) processes in a waveguide

“…The energy of the guided fundamental and SH waves partially generate a group of third harmonic (TH) radiated modes that emit into the substrate. In previous years, some excellent theoretical works about Cherenkov SHG [18,19] have been reported. However, so far there have been few detailed theoretical studies on QPM CTHG via two cascaded χ (2) processes.…”

Cerenkov third-harmonic generation via cascaded χ^(2) processes in a periodic-poled LiTaO_3 waveguide

“…Previous experimental and theoretical investigations on QPM Cerenkov radiations [6][7][8], such as second-harmonic generation (SHG) and sum-frequency generation (SFG), revealed that the QPM Cerenkov configuration has the advantages of high efficiency, wide phase-matching bandwidth, and large tolerance of variations in pump wavelength and waveguide parameters. In a nonlinear waveguide, Cerenkov third-harmonic generation (CTHG) can take place as well [9]. For the realization of CTHG, two possible schemes can be adopted: one is direct CTHG via a χ ð3Þ process and the other bases on two cascaded χ ð2Þ processes.…”