simultaneous second harmonic generation of multiple wavelength laser outputs for medical sensing同时二次谐波发生的多个医疗传感波长激光输出.pdf

Sensors 2011, 11, 6125-6130; doi:10.3390/s110606125 OPEN ACCESS sensors ISSN 1424-8220 /journal/sensors Article Simultaneous Second Harmonic Generation of Multiple Wavelength Laser Outputs for Medical Sensing Seung Nam Son 1, Jae-Jin Song 2, Jin U. Kang 3 and Chang-Seok Kim 1,* 1 Department of Cogno-Mechatronics, Pusan National University, Busan, 609-735, Korea; E-Mail: nami-new@ 2 Department of Otorhinolaryngology, Seoul National University Bundang Hospital, Kyungki, 463-707, Korea; E-Mail: jjsong96@ 3 Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; E-Mail: jkang@ * Author to whom correspondence should be addressed; E-Mail: ckim@pusan.ac.kr; Tel.: +82-55-350-5285; Fax: +82-55-350-5653. Received: 22 April 2011; in revised form: 10 May 2011 / Accepted: 2 June 2011 / Published: 7 June 2011 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 wavelen