We describe a variety of technological advances in the development of efficient, powerful, and continuously tunable Cr:ZnSe lasers operating in the 2.3-2.7 μm spectral region. This includes the development of compact "single chip" waveguide Cr:ZnSe lasers, waveguide mode-locked Cr:ZnSe lasers, and the creation of homogeneously broadened laser material.
In addition to the well-established 5I7 to 5I8 transition at 2.09 μm in holmium doped laser materials, there also exists a less energetic transition from the 5I6 level to 5I7 at 2.95 μm. As there has been a recent increase in interest and applications for 3.0 μm light, this material stands to be a viable alternative to other rare earth doped laser systems. Unfortunately, the wavelength required to directly pump the 5I6 level at 1.13 μm is not convenient for commercial laser diodes. Furthermore, the emission lifetime of the 5I7 state is longer than the 5I6 level, leading to a suppression of lasing due to “bottlenecking” in the material. To overcome these effects, we investigated the activation and deactivation of holmium doped yttrium aluminum garnet (YAG) using ytterbium and praseodymium respectively. By including ytterbium ions in the host material, readily available 914 nm diode light can be used to resonantly excite the 5I6 level in holmium. Similarly, the presence of praseodymium resonantly de-excites the 5I7 state, reducing its lifetime, and making the material more suitable for lasing. Here, we report the absorption and photoluminescence spectra of this triply doped Yb,Ho,Pr:YAG crystal. In addition, the emission lifetime for both the 2.09 μm and 2.95 μm transitions are reported and compared to a Yb,Ho:YAG control sample.