Compact Cr:ZnS Channel Waveguide Laser Operating at 2360 nm

Abstract

A compact mid-infrared channel waveguide laser is demonstrated in Cr:ZnS with a view to power scaling chromium laser technology utilizing the thermo-mechanical advantages of Cr:ZnS over alternative transition metal doped II-VI semiconductor laser materials. The laser provided a maximum power of 101 mW of CW output at 2333 nm limited only by the available pump power. A maximum slope efficiency of 20% was demonstrated.

Spectral-luminescent properties of vapor deposited Cr:ZnS thin films and their application as saturable absorbers for 15-μm erbium lasers

“…Proper processing of the facets and structuring of the films to form a channel waveguide is a key to success on this way. Reactive ion etching [47], ridge waveguide formation by photolithography [48], or femtosecond laser writing [7,49] could be implemented to further improve the waveguiding for both the pump and the laser beam thus increasing the pump intensity and reducing the threshold. We have made preliminary experiments with femtosecond laser writing in bulk crystalline ZnS [50] and are moving forward towards using this technology for thin film samples.…”

“…Transition metal doped zinc chalcogenides are of interest as nonlinear optical materials in the mid infrared, both as active media and saturable absorbers. Continuous-wave (CW) and ultrashort-pulsed sources based on Cr 2+ -doped II-VI crystals [1][2][3][4][5][6][7][8] have come of age and are entering the real-world applications [3,8]. In particular, Cr 2+ :ZnS-based laser systems exhibit robustness, mechanical and optical stability, tens of Watts average power, ultra-broad tuning between 1.9 and 3.2 µm in continuous-wave regime, tens of nJ and GHz repetition rate in femtosecond pulsed regime [3,6], more than 1.5 octave supercontinuum extending from 1.2 to 3.6 μm [9] and direct diode-pumping [10].…”

“…The real-world applications of Cr:ZnS lasers would strongly benefit if these lasers could be produced in a simple and robust waveguide form. The first steps in compact laser fabrication have been made, using inscription of a waveguide structure in a bulk crystal [7] and thin films fabrication has been reported [22], although the pulsed laser deposition (PLD) in that study did not provide the desired optical quality. For Q-switched lasers, a microchip configuration [23] is advantageous due to its robustness, adjustment simplicity, and potential for short pulse generation.…”