Thermal optical properties, Q-switching and frequency tuning of an Nd : LGGG laser based on the 4F3/2 → 4I13/2 transition of a neodymium ion

Laser characteristics of continuous-wave (cw) and passively Q-switched Nd : LGGG lasers based on the ⁴F_3/2 → ⁴I_13/2 transition of an neodymium ion are investigated. The lasing spectra of the cw and the Q-switching regimes are studied in detail. The thermal optical coefficient for the Nd : LGGG crystal at a wavelength of 1.33 μm is estimated to be 15.3 × 10^-6 K^-1. By inserting a quartz plate at the Brewster angle, the frequency of the Nd : LGGG laser is tuned. In the cw regime, the maximum output power at an incident pump power of 7.09 W is 802 mW and a slope efficiency is 13.2%. In the Q-switching regime, a minimum pulse duration of 9.75 ns is obtained with an output power of 176 mW and a repetition rate of 8 kHz. The maximum pulse energy and the highest peak power are 25.4 μJ and 2.4 kW, respectively.