Nonlinear refractive index of ceramic laser media and perspectives of their usage in a high-power laser-driver

Abstract

At the recent years a technology of ceramic laser media on the base of crystals with a cubic symmetry has been developed. The perspective of the usage of ceramic materials in many different applications including high - power short pulse lasers stimulates the work on the systematic study of the properties of these new laser media. A nonlinear refractive index, n2 was studied for several garnet and sesquioxide laser ceramics using Z-scan method. n2 indices in the range of (2-6) × 10-13 were measured for YAG, Y2O3, Lu2O3, and Sc2O3 ceramic samples. These data together with the other laser and spectroscopic parameters of several Nd3+ and Yb3+ doped crystals of a cubic symmetry were used to estimate the properties of laser ceramics for the application in a high-power pulsed-repetitive laser - driver for inertial confinement fusion (ICF) program. A high heat conductivity of ceramic materials is a profitable characteristic for this application as compared to glasses, which are used now for experiments in ICF at single shots regime. Compared to single crystals, ceramic elements provide laser designers with a variety of new design options for the projects of laser-drivers.

Effect of Nd concentration on structural and optical properties of Nd:Y2O3 transparent ceramic

“…However, Y 2 O 3 crystal is extremely difficult to fabricate for its high melting point (2430 1C) and structure phase transition at 2350 1C. An alternative method to single crystal would be transparent ceramic, which shows obvious technological, functional and economic advantages compared with crystal [2]. What is more important, the transparent ceramic can incorporate much larger concentration of doping ions than the crystal, which makes high efficient microchip lasers available.…”

Observation of high-order Stokes and anti-Stokes χ(3)-generation in highly transparent laser-host Lu2O3ceramics

“…Therefore, in near future, the VSN technology of RE 2 O 3 ceramics should solve some problems of this attractive family of crystalline laser materials. It should be noted here that there are also some uncertainties concerning the nonlinear refractive index n 2 (χ (3) ∼ = (2π) −1 n 0 n 2 , here n 0 ≈ 1.9 is the "linear" refractive index) of RE 2 O 3 ceramics, in particular for Lu 2 O 3 ceramics n 2 ≈ 4 × 10 −13 ESU [19]. For high-peak power lasers (on the base Lu 2 O 3 doped with Nd 3+ or Yb 3+ ) relatively large value of n 2 could be a seriously obstacle connected with possible arising the small-scale selffocusing of the laser beam.…”

6-GHz, Kerr-lens mode-locked Yb:Lu_2O_3 ceramic laser for comb-resolved broadband spectroscopy

“…% Yb:Lu 2 O 3 ceramic (with a measured GDD of 75 fs 2 25 fs 2 at 1080 nm determined via white-light interferometry and a reflective index of 1.93 [21]) was cooled to 25°C by a Peltier module, mounted on a copper plate, and placed between the concave mirrors at Brewster's angle. Yb-doped ceramics have been shown to generate short pulses and achieve Kerr-lens mode locking even at high repetition rates owing to the broadband emission spectrum and high nonlinearity resulting from their structure [20,21]. For example, Lu 2 O 3 ceramic has higher nonlinear reflective index of 8.6 × 10 −16 cm 2 ∕W [21] than that of Ti:sapphire crystal, 3.1 × 10 −16 cm 2 ∕W [16].…”

“…Yb-doped ceramics have been shown to generate short pulses and achieve Kerr-lens mode locking even at high repetition rates owing to the broadband emission spectrum and high nonlinearity resulting from their structure [20,21]. For example, Lu 2 O 3 ceramic has higher nonlinear reflective index of 8.6 × 10 −16 cm 2 ∕W [21] than that of Ti:sapphire crystal, 3.1 × 10 −16 cm 2 ∕W [16]. This high nonlinearity helped us to achieve high repetition frequency and stable mode locking.…”