Lithium niobate and lithium tantalate based scalable terahertz pulse sources in reflection geometry.

Gergö O Krizsán,György Tóth,Zoltán Tibai,Gábor Almási,László Pálfalvi,János Hebling

doi:10.1364/oe.405748

Abstract

A new type of THz source, working in reflection geometry, is proposed, where the pulse-front-tilt is introduced by a periodically micro-structured metal profile. For optical coupling, high refractive index nanocomposite fluid is used between the nonlinear optical material and the structured metal surface. Numerical simulations predict ∼87 and ∼85% optimized diffraction efficiencies for lithium niobate and lithium tantalate at 1030 and 800 nm pump wavelengths. The largest diffraction efficiencies can be achieved for a larger refractive index of the nanocomposite fluid than the index of the nonlinear material, for both cases. THz generation efficiencies of ∼3 and ∼1% are predicted for lithium niobate and lithium tantalate, respectively.

Highlights

Among several applications, acceleration of electrons [1,2] and protons [3,4] is a potential use of THz pulses with extremely high pulse energy and peak electric field strength in the low-frequency part of the THz spectrum
Since for 800 nm pump wavelength, the disadvantageous three-photon absorption appears in lithium niobate (LN), lithium tantalate (LT), which has similar linear and nonlinear optical properties as LN but has a larger band gap is considered [21,22]
We introduced an imaging free, plane-parallel, easy-to-manufacture THz pulse source, which is especially advantageous for those nonlinear material (NM) where the necessary PFT is greater than 60◦

Summary

Introduction

Acceleration of electrons [1,2] and protons [3,4] is a potential use of THz pulses with extremely high pulse energy and peak electric field strength in the low-frequency part of the THz spectrum. In the past two-decade lithium niobate (LN) became a compelling material in TPFP sources Several applications, such as particle acceleration and manipulation, require extremely high THz peak electric field strength, which makes necessary the focusing of the THz beam. This wedged NLES setup solves (iii) and significantly reduces (i), and (ii), only a small (

RNLS with ESR

Diffraction efficiency of the ESR

Nanocomposite fluid as HRIL

THz generation efficiencies for RNLS-ESR

Findings

Conclusion