Portable all-fiber dual-output widely tunable light source for coherent Raman imaging

Abstract

We present a rapidly tunable dual-output all-fiber light source for coherent Raman imaging, based on a dispersively matched mode-locked laser pumping a parametric oscillator. Output pump and Stokes pulses with a maximal power of 170 and 400 mW, respectively, and equal durations of 7 ps could be generated. The tuning mechanism required no mechanical delay line, enabling all-electronic arbitrary wavelength switching across more than 2700 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup><mml:mrow><mml:mtext>cm</mml:mtext></mml:mrow> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>1</mml:mn></mml:mrow> </mml:msup> </mml:math> in less than 5 ms. The compact setup showed a reliable operation despite mechanical shocks of more than 25 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mtext>m</mml:mtext></mml:mrow> <mml:mrow><mml:mo>/</mml:mo></mml:mrow> <mml:msup><mml:mrow><mml:mtext>s</mml:mtext></mml:mrow> <mml:mn>2</mml:mn></mml:msup> </mml:math> and is, thus, well suited for operation in a mobile cart. Imaging mouse and human skin tissue with both the portable light source and a commercial laboratory-bound reference system yielded qualitatively equal results and verified the portable light source being well suited for coherent Raman microscopy.