High-Power High Beam Quality 351 nm MOPA System
Publication Date: 2005-Mar-17
The IP.com Prior Art Database
Purpose and advantage of invention: Improve efficiency and divergence of the drive laser operating at 351 nm.
High-Power High-Beam Quality 351NM MOPA System
Purpose and advantage of invention:
Improve efficiency and divergence of the drive laser operating at 351 nm
Short description of invention (Include or attach appropriate sketches, and point out novel features):
We describe efficient UV MOPA system that consists of a solid-state master oscillator (MO) and XeF gas discharge power amplifier (PA). The advantage of this system is that it combines diffraction-limited properties of the solid-state laser beam and high energy and short pulse duration of the excimer PA output. Preferable choice for the MO approach is a diode-pumped laser (DPSS) to provide diffraction limited beam and high pointing stability.
A proper choice for XeF PA is a 3-rd harmonic Nd:
MOlaser, that closely matches spectral properties of XeF excimer gain media, see patent disclosure by W. Partlo and D. Brown, 2004.
The gain spectrum of XeF media has three-branch structure and is shown in the fig. 1.
Fig.1. Level structure of XeF molecule: shows three emission branches of XeF spectrum: 351.1nm, 351.2nm and 353.6 nm. Each branch has structure due to vibration levels of the molecule.
The operating wavelength of Nd:YLF laser is offset, but can be tuned to match two strong 351 nm lines of XeF power amplifier using selective cavity (see invention disclosure “Solid State Master Oscillator for XeF Power Amplifier” Fleurov at all, 2004). However, there is another strong XeF gain line at 353 nm that cannot be seeded with the same MO.
The gain values in excimer laser media are very high. As a result, efficient seeding of PA with MO beam at 351 nm can be only achieved if another gain branch at 353 nm is suppressed. Otherwise, the beam quality and efficiency of the system will be compromised.
In this invention disclosure we propose configuration of MOPA system which consists of a third harmonic Nd:YLF MO and a dual or multi-pass XeF PA with a wavelength selector to suppress amplified stimulated emission (ASE) at 353 nm and to provide good beam quality and efficient operational regime of PA at 351nm.