Long Period Gratings (LPG) in Photonic crystal Fibers (PCF)

LPG fabrication in PCF provides noval features such as very high strain sensitivity and lower thermal sensitivity. LPGs in various types of PCF fibers have been fabricated in FOL/SSLD for sensor applications. Following figure shows the transmission spectrum of Long period grating fabricated in PCF fiber.

Lateral microstructuring of PCF fiber  for sensitive detection of greenhouse gases

The holes in microstructured fibers open up new opportunities for exploiting the interaction of light with gases or liquids. With the possibility of filling the air holes of PCF with gas, with large interaction lengths, new ways to monitor or detect gas are possible. . We have developed a scanning CO₂ laser based technique for lateral access to PCF fibers. The openings can be as small as 50 micron at fiber surface and the depth of the opening can be controlled with a precision of 10 micron. The technique is reliable and fast. Openings have been made in solid core PCFs, hollow core PCFs and Hi-BI PCFs.. The spectral changes due to diffusion of gases was monitored in real time using Optical spectral analyser equipped with a broad band source and a low noise detector.

Microscope image of PCF fiber with U-grooves.

Microscope image of PCF fiber with V-groove.