Power scaling of ultrafast laser inscribed waveguide lasers in chromium and iron doped zinc selenide

Abstract

We report demonstration of Watt level waveguide lasers fabricated using Ultrafast Laser Inscription (ULI). The waveguides were fabricated in bulk chromium and iron doped zinc selenide crystals with a chirped pulse Yb fiber laser. The depressed cladding structure in Fe:ZnSe produced output powers of 1 W with a threshold of 50 mW and a slope efficiency of 58%, while a similar structure produced 5.1 W of output in Cr:ZnSe with a laser threshold of 350 mW and a slope efficiency of 41%. These results represent the current state-of-the-art for ULI waveguides in zinc based chalcogenides.

Mid-IR Ultrafast Laser Inscribed Waveguides and Devices

“…In addition, these sources have been scaled to multi-Watt level output power in non-guided wave devices. A summary of published power level records can be seen in Table 6.1 [29].…”

“…Demonstration of active devices as since been expanded to a variety of materials including YAG [27], glass, ZBLAN, ZnS, ZnSe [28], YLF, and tungstates. Recent advances have lead to increased power output from ULI waveguides of up to 5.1 W [29].…”

Mid-infrared channel waveguides in RbPb 2 Cl 5 crystal inscribed by femtosecond laser pulses

“…Thus we suggest that a waveguide laser based on the rare earth doped RbPb2Cl5 crystal should have higher efficiency and lower threshold than a bulk laser. Feasibility of the waveguiding approach is demonstrated in fs-written channel waveguides in YAG:Yb 3+ crystal [4], YVO4:Nd crystal [5], ZBLAN:Tm 3+ glass [6], YAG:Tm [7], ZnSe:Cr 2+ [8,9], ZnSe:Fe 2+ [9,10] crystals. In these works stress-induced waveguides and depressed cladding waveguide architecture were used [12,13].…”

“…In these works stress-induced waveguides and depressed cladding waveguide architecture were used [12,13]. Tubular cladding (or depressed cladding) architecture of a waveguide allows to keep waveguide core unmodified and to avoid large mechanical stress, thus spectroscopic properties and optical homogeneity of laser medium do not degrade after inscription [5][6][7][8][9][10][11]. This results in low propagation loss and high laser efficiency.…”

“…This results in low propagation loss and high laser efficiency. Applicability of this approach for mid-IR laser was demonstrated on the example of the waveguides inscribed in ZnSe crystal doped with Cr 2+ and Fe 2+ ions [8][9][10]. However ZnSe crystal has spectroscopic restriction for effective operation at room temperature at wavelengths higher 4 µm because of multi-phonon quenching in the delement active ions due to high electron phonon coupling.…”