Multi-stage ramp-up annealing for frequency-conversion crystals

摘要

A frequency-conversion crystal annealing process includes a first ramp-up period (e.g., increasing the crystal's temperature to a first set point in the range of 100° C. to 150° C. over about 2 hours), a first fixed temperature period (e.g., maintaining at the first set point for 10 to 20 hours), a second ramp-up period (e.g., increasing from the first set point to a second set point above 150° C. over about 1 hour or more), a second fixed period (e.g., maintaining at the second set point for 48 to 300 hours), and then a temperature ramp-down period (e.g., decreasing from the second set point to room temperature over about 3 hours). Transitions from the first and second fixed temperature periods are optionally determined by —OH bonds absorption levels that are measured using Fourier transform infrared spectroscopy, e.g., by monitoring the absorption of —OH bonds (including H2O) near 3580 cm−1 in the infra-red spectrum.

主权项

1. A method of annealing a frequency-conversion crystal, the method comprising:
increasing a temperature to about 150° C. over about 2 hours; holding the temperature near 150° C. for about 10 hours; increasing the temperature to about 200° C. over about 1 hour; holding the temperature between 150-200° C. for about 100 hours or longer; and decreasing the temperature down to close to room temperature over about 3 hours.