Optimization and Characterization of Femtosecond Laser Inscribed In-Fiber Microchannels for Liquid Sensing (original) (raw)

Soliton self-frequency shift (SSFS) in a photonic crystal fiber (PCF) pumped by a long-cavity mode-locked Cr:forsterite laser is integrated with second harmonic generation (SHG) in a nonlinear crystal to generate ultrashort light pulses tunable within the range of wavelengths from 680 to 1800 nm at a repetition rate of 20 MHz. The pulse width of the second harmonic output is tuned from 70 to 600 fs by varying the thickness of the nonlinear crystal, beam-focusing geometry, and the wavelength of the soliton PCF output. Wavelength-tunable pulses generated through a combination of SSFS and SHG are ideally suited for coherent Raman microspectroscopy at high repetition rates, as verified by experiments on synthetic diamond and polystyrene films.

We report on the influence of the choice of the pump wavelength relative to the zero-dispersion wavelength for continuum generation in microstructured fibers. Different nonlinear mechanisms are observed depending on whether the pump is located in the normal or anomalous dispersion region. Raman scattering and the wavelength dependence of the group delay of the fiber are found to play an important role in the process. We give an experimental and numerical analysis of the observed phenomena and find a good agreement between the two.

— in every second the modern age of technology is developing and with the improving science we achieve a huge advancement in the field of photonic crystal fiber which offers us a wide range of applications in day to day life. Among all the applications, biosensors have the most innovative potentials. In this paper we proposed a sensor which is designed to sense the liquid with refractive index 1.48 with the sensitivity of 62.56% at the sensing wavelength of 40µm.