Sensors 2011, 11(6), 6125-6130; https://doi.org/10.3390/s110606125
Simultaneous Second Harmonic Generation of Multiple Wavelength Laser Outputs for Medical Sensing
1
Department of Cogno-Mechatronics, Pusan National University, Busan, 609-735, Korea
2
Department of Otorhinolaryngology, Seoul National University Bundang Hospital, Kyungki, 463-707, Korea
3
Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
*
Author to whom correspondence should be addressed.
Received: 22 April 2011 / Revised: 10 May 2011 / Accepted: 2 June 2011 / Published: 7 June 2011
(This article belongs to the Section Physical Sensors)
Abstract
Multiple wavelength light sources in the medical spectral window region are useful for various medical sensing applications in tissue by distinguishing the absorption and scattering coefficients optically. We propose a simultaneous second harmonic generation of multiple wavelength fiber laser output using parallel channels of periodically-poled lithium niobate (PPLN) waveguides. High intensity dual wavelength lasing output is experimentally realized with two tunable fiber Bragg gratings of 1,547.20 nm and 1,554.48 nm for the efficient conversion to the half wavelengths, 773.60 nm and 777.24 nm, by using two parallel PPLN channels. Compared with a conventional dual second harmonic generation (SHG) configuration based on two different input wavelengths from each independent light source, this method has a relatively higher efficiency to align the input light beam into the adjacent parallel PPLN channels simultaneously. The use of fiber lasers offers several advantages since they are relatively inexpensive, provide high power in excess of tens of watts, are widely tunable, and can produce pulses from milliseconds to femtoseconds. View Full-TextKeywords:
hemoglobin concentration; oxygen saturation; second harmonic generation; fiber Bragg gratings; Er-doped fiber laser; multiple wavelength
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MDPI and ACS Style
Son, S.N.; Song, J.-J.; Kang, J.U.; Kim, C.-S. Simultaneous Second Harmonic Generation of Multiple Wavelength Laser Outputs for Medical Sensing. Sensors 2011, 11, 6125-6130.