High power continuous laser at 461 nm based on a compact and high-efficiency frequency-doubling linear cavity

TL;DR

This paper reports a high-power, continuous, single-frequency blue laser at 461 nm achieved through efficient frequency doubling of a 922 nm diode laser, with applications demonstrated in atomic trapping.

Contribution

The work introduces a compact, high-efficiency frequency-doubling linear cavity producing over 1 W of blue light with 87% conversion efficiency, suitable for robust applications.

Findings

Achieved over 1 W blue output power with 87% efficiency.

Demonstrated stable operation over several days.

Successfully used the laser for magneto-optical trapping of Sr atoms.

Abstract

A Watt-level continuous and single frequency blue laser at 461 nm is obtained by frequency-doubling an amplified diode laser operating at 922 nm via a LBO crystal in a resonant Fabry-P\'{e}rot cavity. We achieved a best optical conversion efficiency equal to 87\% with more than 1 W output power in the blue, and limited by the available input power. The frequency-converted beam is characterized in terms of long term power stability, residual intensity noise, and geometrical shape. The blue beam has a linewidth of the order of 1 MHz, and we used it to magneto-optically trap $^{88}$Sr atoms on the 5s$^{2}\,^{1}$S$_0$ -- 5s5p$\,^{1}$P$_1$ transition. The low-finesse, linear-cavity doubling system is very robust, maintains the lock for several days, and is compatible with a tenfold increase of the power levels which could be obtained with fully-fibered amplifiers and large mode area fibers.