Applied Physics B

, Volume 79, Issue 3, pp 331–339

Optical characterization of semiconductor saturable absorbers


DOI: 10.1007/s00340-004-1535-1

Cite this article as:
Haiml, M., Grange, R. & Keller, U. Appl. Phys. B (2004) 79: 331. doi:10.1007/s00340-004-1535-1


Semiconductor saturable absorber mirror (SESAM) devices have become a key component of ultrafast passive mode-locked laser sources. Here we describe in more detail how the key SESAM parameters such as saturation fluence, modulation depth, and nonsaturable losses are measured with a high accuracy. These parameters need to be known and controlled to obtain stable pulse generation for a given laser. A high-precision, wide dynamic range setup is required to measure this nonlinear reflectivity of saturable absorbers. The challenge to measure a low modulation depth and key measures necessary to obtain an accurate calibration are described in detail. The model function for the nonlinear reflectivity is based on a simple two-level travelling wave system. We include spatial beam profiles, nonsaturable losses and higher-order absorption, such as two-photon absorption and other induced absorption. Guidelines to extract the key parameters from the measured data are given.

Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  1. 1.Swiss Federal Institute of Technology (ETH) Physics Department/Institute of Quantum ElectronicsETH Zurich Hoenggerberg HPTZurichSwitzerland