Femtosecond bulk transparent material processing and recovery.

Femtosecond lasers have a unique ability of processing bulk transparent materials for various applications such as micromachining, waveguide manufacturing, and photonic bandgap structures, just to name a few. These applications depend on the formation of micron or submicron size features are known to be index modifications to the bulk substrate [2, 11], which were thought to persist indefinitely. However, it has been observed that some of these bulk transparent materials recover or "heal" with time.

Optical temperature sensor and thermal expansion measurement using a femtosecond micromachined grating in 6H-SiC.

An optical temperature sensor was created using a femtosecond micromachined diffraction grating inside transparent bulk 6H-SiC, and to the best of our knowledge, this is a novel technique of measuring temperature. Other methods of measuring temperature using fiber Bragg gratings have been devised by other groups such as Zhang and Kahrizi [in MEMS, NANO, and Smart Systems (IEEE, 2005)]. This temperature sensor was, to the best of our knowledge, also used for a novel method of measuring the linear and nonlinear coefficients of the thermal expansion of transparent and nontransparent materials by means of the grating first-order diffracted beam.

Femtosecond micromachining in transparent bulk materials using an anamorphic lens.

A unique anamorphic lens design was applied to a circular 780nm femtosecond laser pulse to transform it into an elliptically shaped beam at focus. This lens was developed to give an alternative method of micromachining bulk transparent materials. The challenge for femtosecond laser processing is to control the nonlinear affect of self-focusing, which can occur when using a fast f-number lens.