Tion, with this architecture, it really is less difficult to attain mode matching and right thermal management, because the two cavities are separated. The experimental setup in the Raman laser and its fundamental pump source is shown in Figure 1. The pump laser was an EO actively Q-switched Tm:YAP laser. The EOM operated using the polarization modulation approach that was described in detail in a preceding study [22]. The cavity included a ten mm length a-cut Tm:YAP (3 at.) crystal using a 3 3 mm2 cross-section, as a acquire medium, end-pumped by a 30 W, 793 nm laser-diode. The pump beam was focused to a beam diameter of 330 inside the Tm:YAP crystal. Both the diode and Tm:YAP crystal had been water-cooled to 18 . A plano-concave mirror with a 200 mm radius of curvature (ROC) was applied as an input mirror, possessing an AR coating at the pump wavelength, along with a higher reflectance (HR) coating at 1850000 nm. A plano-concave mirror having a 100 mm ROC was utilised as an output coupler (OC) using a GSK2646264 manufacturer partially reflecting (PR) coating of 55 reflectance for the 1850000 nm. The cavity length was 150 mm. The EOM was according to a KLTN electro-optic crystal. The crystal had a trapezoidal shape to minimize acoustic waves inside the crystal. The KLTN crystal was 2 mm extended, and also the clear aperture was three 3 mm2 . The KLTN crystal was installed in a temperature-controlled holder that maintained its temperature at six degrees above the phase transition temperature. A quarter wave plate (QWP) was inserted in between the Tm:YAP and the KLTN. When the QWP axes was tilted 45with respect to the crystals axes the modulator was in “off” state. an uncoated yttrium aluminum garnet (YAG) etalon plate, with one hundred thickness, was inserted into the laser cavity to narrow the laser spectral line. The lasing wavelength was measured to be 1935 nm. The pulse duration was measured to have a 19 ns complete width at half-maximum (FWHM). The laser beam was linearly p-polarized. The output beam in the Tm:YAP was imaged by a pair of antireflective (AR) coated, plano-convex lenses, to a spot diameter of 220 inside the center in the KGW crystal. As a consequence of the divergence of your beam, the beam size enhanced to 300 at the facets of the Raman crystal. A half-wave-plate (HWP) was added among the lenses to handle the polarization orientation and allow switching between the two various Raman vibration shifts of the KGW crystal, thereby enabling JNJ-42253432 Protocol selective lasing at 2273 and 2344 nm. Such an external cavity configuration is advantageous for any two-wavelength Raman laser, since it enables for uncomplicated switching between the two Raman-shifted modes.Photonics 2021, 8,four ofFigure 1. Experimental setup in the external KGW Raman laser and its actively Q-switched Tm:YAP seed laser.A plano-plano mirror, AR coated for 1860960 nm and HR coated for 2170700 nm, was utilised as an input mirror for the Raman laser cavity, plus a plano-concave mirror having a one hundred mm ROC was employed as an OC. This mirror had a PR-coating of 93 reflectance in between 2170 and 2450 nm and HR coating for 1850960 nm, enabling double-pass pumping in the 30 mm extended KGW crystal, which was utilized as the active Raman medium. The crystal was AR coated for the basic and Raman wavelengths, and its cross-section was 7 7 mm2 . This crystal was oriented for propagation along the b-axis, possessing 901 cm-1 shift and 768 cm-1 shift, for E (electric field) perpendicular towards the c-axis and a-axis, respectively, [16]. As talked about ahead of, the control of the electric field polarization was facilitated usin.
