Measurement of nonlinear optical reflectivity of saturable absorber devices is discussed. A setup is described that enables absolute accuracy of reflectivity measurements better than 0.3%. A repeatability within 0.02% is shown for saturable absorbers with few-percent modulation depth. The setup incorporates an in situ knife-edge characterization of beam diameters, making absolute reflectivity estimations and determination of saturation fluences significantly more reliable. Additionally, several measures are discussed to substantially improve the reliability of the reflectivity measurements. At its core, the scheme exploits the limits of state-of-the-art digital lock-in technology but also greatly benefits from a fiber-based master-oscillator power-amplifier source, the use of an integrating sphere, and simultaneous comparison with a linear reflectivity standard.
© 2014 Optical Society of America
Original Manuscript: May 2, 2014
Revised Manuscript: June 2, 2014
Manuscript Accepted: June 18, 2014
Published: July 22, 2014
Lasse Orsila, Antti Härkönen, Janne Hyyti, Mircea Guina, and Günter Steinmeyer, "Ultrahigh precision nonlinear reflectivity measurement system for saturable absorber mirrors with self-referenced fluence characterization," Opt. Lett. 39, 4384-4387 (2014)