Efficient terahertz generation by optical rectification in Si-LiNbO3-air-metal sandwich structure with variable air gap

Abstract

A record high optical-to-terahertz conversion efficiency of 0.25% was realized with femtosecond laser pulses propagated in a planar Si-LiNbO3-air-metal structure. Terahertz spectrum tuning was demonstrated by adjusting an air gap between the LiNbO3 layer and the metal plate. The influence of optical pulse chirp on the efficiency of terahertz generation was investigated.

Diffraction-Limited High-Power Single-Cycle Terahertz Pulse Generation in Prism-Cut LiNbO3for Precise Terahertz Applications

“…However, the large index dispersion and mismatch in LiNbO3 inhibit efficient phase matching in a collinear geometry. Since Hebling et al suggested a non-collinear phase matching in a prism-cut LiNbO3 using a tilted pulse-front pumping (TPFP) scheme and reported its proof-of-principle experiment for efficient THz pulse generation in 2003, many efforts have followed to improve both THz pulse energy and spectral bandwidth by utilizing different configurations and excitation sources [15][16][17]. As a result, it turned out that there was a tradeoff between the pump-to-THz conversion efficiency and the spectral bandwidth for THz pulse generation.…”

Absorption-reduced waveguide structure for efficient terahertz generation

“…[1][2][3][4][5][6][7][8][9] In case of materials with high nonlinearity but strong absorption in the THz range, such as LiNbO 3 (LN) with d 33 ¼ 168 pm/V nonlinear optical coefficient 10 and tens of cm À1 absorption coefficient, 11 it is important to suppress absorption. A promising way to achieve this is to sandwich a few lm thick LN layer between layers of significantly smaller absorption.…”

“…A promising way to achieve this is to sandwich a few lm thick LN layer between layers of significantly smaller absorption. [1][2][3][4][5] A suitable material for such a lowabsorption cladding is silicon (Si). The structures reported so far are guiding only the optical pump; 1-5 the selected material parameters and dimensions do not allow wave guiding in the THz range.…”

Asymmetric Cherenkov radiation for improved terahertz generation in the Si-prism-coupled LiNbO_3 layer

“…We propose using this phenomenon to improve the spectral characteristics of one of the most efficient optical-to-terahertz converters: a thin LiNbO 3 layer attached to a Si-prism outcoupler.One of the most efficient optical-to-terahertz converters is the structure consisting of a thin (∼30 − 50 μm thick) layer of LiNbO 3 (LN) attached to a Si-prism outcoupler [1][2][3][4][5]. A femtosecond laser pulse propagates in the LN layer as a guided mode and produces (via optical rectification) nonlinear polarization, which follows the optical intensity envelope.…”