25 October 2016 MWIR optical modulation using structured silicon membranes
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Abstract
We have used near IR pump – Mid IR probe techniques to compare the feasibility and potential of using free standing nano-porous and micro-porous silicon (ordered hole arrays) as optically controlled modulators operating in the Mid-Wave Infrared (MWIR) covering the range from 3.3-5 μm. We employed 800 nm pumping pulses with the duration of 60 fs to reduce 4 μm light transmission modulation to about 25% and 45% for both silicon structures, respectively, at excitation powers of 50mW (4 mJ=cm2). However, at 5 μm both structures shown similar contrast of about 60%. The time resolved measurements revealed a fast sub-picosecond rise time for both structures suggesting that the optically generated carriers are a dominant mechanism for the modulation. However, the measurements demonstrated a significant difference in the relaxation dynamics. The nanoporous silicon demonstrated recovery as fast as a few tens of picoseconds and a possibility to effectively work in the GHz regime, while hole arrays shown almost three orders of magnitude slower response making it suitable for the MHz regime.
Conference Presentation
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A. Zakar, S. J. Park, V. Zerova, A. Kaplan, Leigh T. Canham, K. L. Lewis, C. D. Burgess, "MWIR optical modulation using structured silicon membranes", Proc. SPIE 9992, Emerging Imaging and Sensing Technologies, 999203 (25 October 2016); doi: 10.1117/12.2242287; https://doi.org/10.1117/12.2242287
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