Dynamics and long-term stability of single and multi-longitudinal mode 473-nm diode-pumped Nd:YAG/KNbO3 lasers
Oxxius 473 nm blue laser sources today
Published at SPIE Photonics West 2005, this paper addresses one of the central engineering challenges in compact blue DPSS laser design: achieving reliable, long-term single-frequency operation at 473 nm in a Nd:YAG/KNbO3 microchip architecture. Through detailed modelling of laser dynamics — including hole burning, quenching, and type-I frequency doubling — the authors demonstrate that even in multimode operation, only one longitudinal mode oscillates at a time, switching at approximately 50 kHz. This behaviour, distinct from the well-known “green noise” of type-II intracavity doubling, was experimentally confirmed and informed Oxxius’s approach to power-stable blue laser design.
The 473 nm wavelength is a standard excitation line in flow cytometry, confocal microscopy, and Raman spectroscopy, where it serves as a compact, efficient replacement for air-cooled argon ion lasers. The stability work described here underpins the LBX-473 and LCX-473 laser sources that Oxxius produces today for integration into scientific instruments and OEM systems.
Abstract
Diode pumped frequency doubled Nd :YAG microchip lasers should become an alternative to air-cooled argon ion lasers. The main issues to be solved are the long-term stabilization of the single frequency operation and the power control of the multi-frequency operation. These questions are mostly related to the laser dynamics. In this paper, we present an accurate modelling of the laser dynamics, including quenching processes, non uniform pumping, partial overlap of optical signals and excited-state populations, hole burning and type-I frequency doubling. We theoretically predict that even in multimode operation, only one mode is oscillating at a time, with a mode hoping at a rate of about 50 kHz. This behavior, quite different from the well known dynamics of intra-cavity type-II frequency doubled lasers (green noise) is experimentally confirmed. Diode pumped frequency doubled Nd:YAG 473 nm lasers based on …