Semiconductor saturable absorber mirror with wavelength tailored distributed Bragg reflector

Abstract

Multi-component semiconductors offer broadband absorption/gain characteristics. In actual devices, however, usable bandwidth of surface-normal devices, e.g. vertical cavity surface emitting lasers, semiconductor saturable absorber mirrors, is limited by the stopband of the distributed Bragg reflector. Using wavelength-tailored distributed Bragg reflectors is a possible solution to extend the operation range in tunable lasers. This study explores the potential of the molecular beam epitaxy technology for preparing monolithic surface-normal semiconductor saturable absorber mirrors for wavelength-tunable ultra-short pulse production. An exceptionally large stopband of a semiconductor saturable absorber mirror of 230 nm, from 1.46 to 1.69 μm, was demonstrated with spatial translation of the wavelength-tailored distributed Bragg reflectors. The tunable operation of the pulsed fiber laser obtained with molecular beam epitaxy grown graded mirrors confirms the capability of this technology. Using these devices as cavity-end mirrors in erbium-doped fiber lasers we could generate and maintain Q-switched and mode-locked picosecond optical pulses over a wavelength range of about 10 nm.