Enhancement of Cr⁴⁺ Concentration in Y₃Al₅O₁₂ Crystal Fiber by Pregrowth Perimeter Deposition

Abstract

Chromium ions tend to diffuse outward during the laser-heated pedestal growth (LHPG) of Y 3 Al 5 O 12 (YAG) crystal fiber, in which the average Cr 4þ ion concentration decreases significantly after each diameter-reduction step. The Cr 4þ ions are replenished using an electron gun to deposit Cr 2 O 3 and divalent-ion oxide (CaO or MgO) on the source rod circumference before LHPG. It was observed that Ca 2þ has better efficiency to diffuse into the source rod more efficiently than Mg 2þ generating fewer defects and stacking faults. By CaO deposition and post growth annealing at 1350 C under an oxygen environment, a 110% increase in Cr 4þ concentration was obtained. The achieved Cr 4þ concentration and the ratio of Cr 4þ to total Cr were 1:76 Â 10 18 cm À3 and 5.5, respectively. The Ca,Cr:YAG crystal fiber can thus be used as an ultra broadband laser material and amplified spontaneous emitter.

Simulation and experiment on laser-heated pedestal growth of chromium-doped yttrium aluminum garnet single-crystal fiber

“…They are recognized for their remarkable characteristics, such as low defect density, long mode confinement length, and good laser efficiency. These advantages enable their applications in passive devices [2,3], active devices [4][5][6][7][8][9][10][11], and nonlinear fiber devices [12][13][14]. For various kinds of high quality crystal fiber devices, the concentration level and distribution of dopants in the melt, especially at the growth front, are necessary to be designed and optimized finely.…”

Two-Dimensional Simulations on Heat Transfer and Fluid Flow for Yttrium Aluminium Garnet Single-Crystal Fiber in Laser-Heated Pedestal Growth System

“…1) They are recognized for their remarkable characteristics, such as low defect density leading to high optical damage threshold, long modeconfinement length leading to high nonlinear wavelength conversion efficiency, and good laser efficiency upon doping with transition metals. These advantages enable their application in passive devices, 2,3) active devices, [4][5][6][7][8][9][10][11] and nonlinear fiber devices. [12][13][14] Among the floating-zone (FZ) methods, 15) pedestal growth 16) has so far proved to be the most versatile method when using laser heating; 17) this method is also known as the laser-heated pedestal growth (LHPG) technique.…”

Fabrication and characterization of Cr:forsterite single crystal fiber

“…Uniform refractive index cladding for LiNbO 3 single-crystal fibers by using Mg ion indiffusion process has been obtained [16] . In recent years, this fiber growth technique has been further developed and modified by S. L. Huang, et al [17][18][19][20][21][22][23][24][25][26][27][28] to grow single-crystal-core double-clad optical fibers. Based on the same technology in this work, we performed the first Cr:forsterite fiber growth and material characterization.…”