Patent ID: 7970039

Claim:
A laser amplifier including a solid state laser gain medium, the solid state laser gain medium having first and second ends along a laser optical axis in which each end is profiled concave to provide a level of thermal lens compensation at a desired operating pump power such that the beam has a beam quality factor M 2 maximized at the desired operating pump power, wherein the solid state laser gain medium is configured to operate in a laser oscillator cavity that is optically symmetrical and includes flat cavity end reflectors, said laser amplifier further comprising: a laser cavity; and an amplifying module external to the laser cavity, said amplifying module sharing a common axis of emission with said laser cavity and comprising an amplifier gain medium having first and second ends along said axis of emission; whereby at least one of said first or second ends of said amplifying module is profiled to produce a lensing effect so as to directly couple light from said laser cavity into said amplifying module.