Doping profile influence on a polycrystalline Cr²⁺:ZnSe laser efficiency

Abstract

Cr2+:ZnSe polycrystalline active elements were fabricated, with different distribution profiles of Cr ions concentration over their thicknesses and an equal absorption at a pump wavelength of 1.9 µm. The lasing characteristics of the obtained samples in short cavity schemes were determined, using a CW Tm3+-doped fiber laser and a Tm3+:YLF pulsed laser as the sources of pumping. There was found to be a correlation between the generation slope efficiency and the shape of the concentration profile. It was determined that bilateral doping samples achieved better laser performance. The maximum values of the slope efficiencies with respect to the absorbed power were η =73% in the pulse-periodic mode, and η = 37% in the continuous-wave mode.

Photoluminescence and laser properties of active media based on ZnSe doped with Cr, Al, Na from spray pyrolysis deposited films

“…The absorbed power efficiency for these samples was about 54% and 50% respectively. Taking into account the resonator geometry and the absence of cooling, it is comparable to the results for polycrystalline ZnSe:Cr samples produced using traditional technology [15]. The lasing efficiencies of ZnSe:Cr:Na[CdS] and ZnSe:Cr:Al[CdS] samples were significantly lower (23% and 8%, respectively).…”

“…The transmission spectra obtained using a Bruker Tenzor-27 FT-IR spectrometer showed a broad absorption band due to Cr 2+ ions with a peak absorption wavelength near 1.8 µm for all the samples. The measured absorption at a wavelength of 1.94 µm of Tm:YAP laser, which was subsequently used to study the luminescence and laser characteristics of the samples, was about 65% for ZnSe:Cr[CrS], For the next stage of the work, the distribution profiles of optically active centers were obtained for all samples (figure 1) according to the method described in detail in [15]. The essence of the method was to scan the sample across the diffusion direction using a narrowly focused Tm:YAP laser beam.…”

Cr2+:ZnSe active media with complex profiles of internal doping

“…Figure 2 shows the distribution of Cr 2+ ion concentration against samples depth. The technique for concentration profiles measuring was detailed by us earlier in [15]. As expected, the maximum local concentrations have been achieved at the bonding boundaries and are equal to 0.8 × 10 19 cm −3 for samples with two doped layers (samples Nos.…”

“…The generation curves of the test samples obtained with continuous operation modes are shown in figure 3. Iin the course of the experiment, the thermal bend of generation curve was not observed until the values of the absorbed pump power of 2.55 W. At the same time, the output characteristics of the best surface-doped samples were significantly reduced already at the pump power of 2.1 W [15] It is worth noting that the samples with internal doping were placed inside the cavity without any cooling, while the surface-doped samples were fixed in a copper radiator, providing an effective heat removal from the lateral surfaces.…”

“…The output signal was detected by the laser power meter Coherent FieldMax II and the resonator was adjusted using a Pirocam III pyroelectric chamber. This cavity geometry was already used in our previous study [15]; the only difference is that now the pump beam was directed normally to an active element.…”