A few-cycle Cr⁴⁺:YAG laser and optical studies of photonic crystals

Abstract

A prismless Cr4+:YAG laser was used to generate 20 fs pulses at 1450 nm with a bandwidth of 190 nm FWHM. Intracavity group velocity dispersion was compensated with double-chirped mirrors. Pulse spectrum was observable from 1140 to >1700 nm. Broadband saturable Bragg reflectors were designed and used to ensure self-starting of 35 fs pulses in the ultrafast Cr4+:YAG laser or to generate picosecond pulses tunable from 1400 to 1525 nm. The mirrors were a 7-pair GaAs/AlxOy quarter-wave dielectric stack, and the absorber consisted of a InGaAs quantum well centered in a half-wave InP layer. Transmission was measured through a photonic bandgap crystal microcavity resonant near 1550 nm. Cavity quality factors as high as 360 were observed for cavities with a modal volume of only 2([lambda]/2n)3. Photonic crystals were used to enhance the total emission of a light emitting diode at 980 nm by 8-fold. At particular wavelengths, collected photoluminescence enhancements larger than 100 were observed.