Femtoline Low GDD Mirrors

Group Delay Dispersion (GDD) is a fundamental parameter in ultrafast optics that characterizes the variation in the phase delay experienced by different spectral components of a light pulse as it propagates through an optical system. Excessive GDD can lead to pulse broadening, temporal distortion, and decreased efficiencies in various applications such as spectroscopies, microscopies, and laser processing. Femtoline Low GDD Mirrors are designed to minimize GDD (i.e. linear phase versus frequency characteristics)  while maximizing reflection rate across a specific spectral range, securing minimal temporal dispersion of femtosecond laser pulses. The low GDD characteristic is essential for preserving pulse duration and achieving high-resolution performance in ultrafast applications.

Metal mirrors made of gold or special enhanced silver mirrors with low dispersion are an economical choice, but metal mirrors have limited reflection and high absorption losses, making them disadvantageous for lasers of high energies. Dielectric low GDD mirrors are engineered to provide high reflection with minimized GDD over a narrow bandwidth of central wavelengths. Compared to Ultrafast Enhanced Silver Mirrors (which are also available in Shalom EO, click on the link to learn more), Low GDD Mirrors utilizing dielectric coatings have a higher reflection coefficient and higher damage threshold, making them conducive for high-power femtosecond laser applications, however, low GDD mirrors are devised to operate within a smaller wavelength range than ultrafast enhanced silver mirrors.

Shalom EO's Femtoline Low GDD Mirrors are engineered to achieve exceptional reflection across a narrow bandwidth centered around the central wavelength of femtosecond lasers. These mirrors are coated with dielectric low GDD coatings that minimize temporal dispersion femtosecond pulses during their propagation. The mirror substrates are crafted from Corning UV fused silica 7980 0F, a material renowned for its outstanding optical properties, mechanical robustness, and minimal thermal expansion, ensuring high performance and durability. High-precision controlling techniques are harnessed to enhance to a precision standard of  λ/10 flatness and 10/5 S/D surface quality.

Hangzhou Shalom EO offers stocked Low GDD mirrors optimized for high reflection within specific wavebands or wavelengths, including 400nm, 532nm, 800nm, 808nm, 760-840nm, 1030nm, 1000-1060nm, and 1064nm, accommodating incident angles of 0 degrees and 45 degrees. In addition, customized Low GDD mirrors tailored to other reflection wavebands and wavelengths with free design services are available upon request, providing versatility to suit diverse application needs.

Application Notes: 

For s-polarization, high-reflection mirrors have better reflection, wider operating spectrum, and lower pulse distortion than for p-polarization. So it is more recommendable to use the mirrors with the p-polarized beam as possible as you can.