Recent years have seen rising interest in optical system-on-a-chip sensors for biological applications. Vertical cavity surface emitting lasers (VCSELs) are a natural choice for array-based sensors requiring high power and low noise. However, much of the noise characterization of VCSELs has been performed in frequency ranges on the order of 10⁸ to 10¹⁰ Hz, whereas many physiological phenomena occur in frequency bands in the hertz to kilohertz range where 1/f and 1/f² noise is dominant. In this work we characterize the relative intensity noise (RIN) of commercial VCSEL devices and evaluate their feasibility for use in an integrated semiconductor optical sensor for functional brain imaging using Intrinsic Optical Signals (IOS). Our results show RIN on the order of -196 to -174 dB/Hz at an offset of 10 Hz. This is well below the signal-to-background and dynamic range requirements of 6 dB and 86 dB, respectively, for this application.

Date Published: 8 February 2008
PDF: 8 pages
Proc. SPIE 6842, Photonic Therapeutics and Diagnostics IV, 68422T (8 February 2008); doi: 10.1117/12.764143

Published in SPIE Proceedings Vol. 6842:
Photonic Therapeutics and Diagnostics IV
Kenton W. Gregory M.D.; Reza S. Malek M.D.; Nikiforos Kollias; Brian Jet-Fei Wong M.D.; Henry Hirschberg M.D.; Justus F. R. Ilgner M.D.; Steen J. Madsen; Guillermo J. Tearney M.D.; Bernard Choi; Haishan Zeng, Editor(s)