Nd concentration optimization for efficient low-cost 473-nm diode-pumped Nd: YAG/KNbO3 microchip assembly

Oxxius 473 nm blue laser sources today

Published at SPIE Photonics West 2004, this paper represents Oxxius’s earliest systematic work on the 473 nm Nd:YAG/KNbO3 microchip architecture. By modelling and measuring thermal lensing, beam evolution, and Nd concentration effects within a 2.1 mm microchip assembly, the authors identified the key parameters limiting efficiency in linear cavity designs — and demonstrated 40 mW CW output at 473 nm with high beam quality (M² < 1.2) from under 900 mW of launched pump power.

This foundational efficiency work, combined with the mode dynamics and stability studies that followed in 2005, established the design basis for Oxxius’s compact blue laser product line. The 473 nm wavelength is widely used in flow cytometry, confocal microscopy, and Raman spectroscopy as a solid-state replacement for the air-cooled argon ion laser. Oxxius’s current LBX-473 sources build directly on this research, delivering stable, low-noise CW output in a compact, OEM-ready format.

Abstract

Although powerful (2.8 W) blue emission at 473 nm was recently reported, the design of low-cost compact and efficient 473 nm source failed so far. We have theoretically and experimentally analyzed the operation of a simple 2.1 mm long microchip assembly pumped by a 100×1 μm laser diode and found several ways to improve the efficiency of such a laser. As a first result, we achieved high beam quality (M2<1.2) 40 mW CW operation @ 473 nm with less than 900 mW launched power (5% efficiency) and small low-frequency (10Hz-20 kHz) noise. Multi-frequency operation however led to high-frequency noise (green problem). To our best knowledge, this is the highest efficiency obtained with a linear cavity. In this paper, we model and measure thermal lensing, pump, 946 nm and 473 nm beam size and power evolution within the MCA. Nd concentration was left unoptimized in previously reported experiments to …