20 February 2007 Semiconductor saturable absorbers with recovery time controlled through growth conditions
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Proceedings Volume 6451, Solid State Lasers XVI: Technology and Devices; 645113 (2007); doi: 10.1117/12.725397
Event: Lasers and Applications in Science and Engineering, 2007, San Jose, California, United States
Abstract
We discuss a new method to shape the temporal response of saturable absorption in semiconductors. In particular, we investigate the possibility to control independently the absorption recovery time of each quantum-well forming the semiconductor absorber. The recovery time is tailored by irradiation with nitrogen ions produced by an RF-plasma source. The irradiation is performed in-situ as one step of the epitaxial growth process; the quantum-wells are individually exposed to a flux of N-ions after they are grown. The amount of non-radiative recombination centers within the quantum-wells is strongly related to the time interval during which the N-ions flux is active and to the thickness of the semiconductor layer grown on top of each quantum-well before the irradiation is performed. We apply this method to fabricate fast semiconductor saturable absorbers operating in the 1-&mgr;m wavelength range. The absorption recovery time could be changed from 300 ps to 10 ps without degradation of the nonlinear optical response. The practicality of the design is finally proved by using the semiconductor saturable absorbers for mode-locking Yb-doped fiber lasers.
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Mircea D. Guina, Pietari Tuomisto, Oleg G. Okhotnikov, Saulius Marcinkevicius, Kenichiro Mizohata, Juhani Keinonen, "Semiconductor saturable absorbers with recovery time controlled through growth conditions", Proc. SPIE 6451, Solid State Lasers XVI: Technology and Devices, 645113 (20 February 2007); doi: 10.1117/12.725397; https://doi.org/10.1117/12.725397
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KEYWORDS
Semiconductors

Quantum wells

Ions

Picosecond phenomena

Absorption

Gallium arsenide

Mode locking

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