Near-infrared supercontinuum generation in conventional single mode fiber used in optical sensor

Abstract

The near-infrared supercontinuum light was generated in a single mode optical fiber by the femtosecond pulses from an unamplified Ti:sapphire laser. The light source possesses properties of high repetition rate, peak power, and low optical damage, and thus can used for optical sensors. Supercontinuum generation is a complex nonlinear phenomenon that is characterized by the dramatic spectral broadening of intense light pulses passing through a nonlinear material. Special fibers, such as the fluoride fiber and tapered fiber, spanning over three octaves from UV to 3.85 m and over two octaves from 370~1550 nm, respectively, are used to generate the supercontinuum. The spectra span more than an octave and retain the longitudinal mode structure of the mode-locked laser source, which recently led to spectacular advances in optical frequency metrology. In this study, a conventional single mode optical fiber with a cladding-free central section immobilized metal nanoparticles was used to generate the near-infrared supercontinuum light. The absorption spectrum of nanoparticals on the optical fiber can be measured by the homemade tunable near-infrared supercontinuum light source from the single mode fiber. It offers a simple and cost-effective method to generate a near-infrared light source to serve for spectral measurements and achieving the fiber-optic sensing.