Studying the Nonlinear Optical Properties of Fluoride Laser Host Materials in the Ultraviolet Wavelength Region

Duong Van Pham,Minh Hong Pham,Diep Van Nguyen,Marilou Cadatal-Raduban,Kieu Anh Thi Doan,Quan Minh Le,Tu Xuan Nguyen

doi:10.3390/app12010372

Duong Van Pham, Minh Hong Pham + Show 5 more

Open Access

https://doi.org/10.3390/app12010372

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Abstract

Fluoride host materials doped with trivalent cerium ions have previously been demonstrated as successful laser materials in the ultraviolet wavelength region. However, the nonlinear optical properties of the fluoride hosts in this wavelength region have not been investigated yet, although nonlinearity could result in undesirable effects such as self-focusing and pulse distortion when these fluoride materials are used as gain media in high-power, ultrashort pulse laser oscillator and amplifier systems. In this work, the nonlinear refractive index of lithium calcium aluminum fluoride (LiCaAlF6), lithium strontium aluminum fluoride (LiSrAlF6), lanthanum fluoride (LaF3), and yttrium lithium fluoride (YLiF4) fluoride host materials are determined using the Kramers–Krönig relation model in the ultraviolet wavelength region. Self-focusing conditions, particularly at the peak laser emission wavelength of these materials, are further analyzed. Results show that LiCaAlF6 has the smallest nonlinear refractive index and self-focusing, making it an ideal host material under the conditions of ultrashort pulse and ultrahigh-power laser generation.

Highlights

Ultrashort, high-peak-power lasers such as femtosecond and attosecond lasers have become indispensable in many applications spanning the fields of physics, chemistry, biology, medicine, and engineering [1,2]
In conclusion, the nonlinear refractive index (n ) of different fluoride laser materials including lithium calcium aluminum fluoride (LiCAF), lithium strontium aluminum fluoride (LiSAF), YLF, and lanthanum fluoride (LaF) were determined for the first time using the Kramers–Krönig relation model in the UV region
The nonlinear refractive index (n2) of different fluoride laser materials including LiCAF, LiSAF, YLF, and LaF were determined for the first time using the Kramers– Krönig relation model in the UV region

Summary

Introduction

Ultrashort, high-peak-power lasers such as femtosecond and attosecond lasers have become indispensable in many applications spanning the fields of physics, chemistry, biology, medicine, and engineering [1,2]. Ultrashort lasers operate fundamentally in the infrared region, but there is much demand in the ultraviolet (UV) wavelength region for numerous applications, including time-resolved spectroscopy [3], micromachining for the fabrication of micro-lens arrays, photonic crystals, optical waveguides, gratings, micro-sized optical sensors [4,5], high-efficiency laser processing of materials [6], and high-resolution ultrafast imaging [7]. High-order harmonic generation using nonlinear crystals has been utilized to convert ultrashort laser pulses from the fundamental infrared to UV wavelengths. Direct generation of pulsed tunable UV laser wavelengths has been achieved using trivalent cerium ion (Ce3+)-doped fluorine-based host materials. Based on the dipole-allowed interconfigurational 5d–4f transitions in the Ce3+ activator ions, these new class of solidstate tunable UV lasers are efficient, compact, and are especially attractive for ultrashort pulse generation and amplification in the UV wavelength region

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