Q-switched Ho:YLF laser pumped by a Tm:GdVO4 laser.

Content Provider	Semantic Scholar
Author	Esser, M. J. Daniel Strauss, Hencharl Johan Koen, W. Preussler, D. R. Nyangaza, K. Bollig, Christoph
Copyright Year	2009
Abstract	We have, through careful analysis of spectroscopic data, designed and demonstrated a diode-end-pumped, quasicontinuous wave Tm:GdVO4 laser operating at 1892 nm in order to pump a Q-switched Ho:YLF laser. The Ho:YLF maximum output energy was 1.9 mJ in an 18 ns pulse, at a wavelength of 2050 nm. Type 1: Oral or Poster Q-switched Ho:YLF Laser Pumped by a Tm:GdVO4 Laser M. J. Daniel Esser,* H. Strauss, W. S. Koen, D. Preussler, K. Nyangaza and C. Bollig National Laser Centre, Council for Scientific and Industrial Research, PO Box 395, Pretoria, 0001, South Africa (*desser@csir.co.za) INTRODUCTION Orthovanadates are attractive host crystals for rare-earth doped diode-pumped solid-state lasers. This is also the case when doped with Tm or Ho, which have been shown to exhibit certain advantages over other host crystals for Mid-IR lasers. In particular, it has been shown that Tm:GdVO4 has strong and broad absorption features at the emission wavelength of commercially available high power laser diodes at ~800 nm. In addition, the broad emission peak at 1.9 μm in Tm:GdVO4 can be utilised for laser operation over a wide wavelength tuning range, including wavelengths which can be used to pump Ho and Cr:ZnSe lasers. The highest laser output power was reported by Li et al who achieved a maximum continuous-wave output power of 2.8 W from a diode-end-pumped Tm:GdVO4 laser. 4 In addition, with the use of an intra-cavity birefringence filter, they demonstrated a tuning range of 126 nm (1820 to 1946 nm). More recently, a comparative study of the tuning ranges of Tm:YVO4, Tm:LuVO4 and Tm:GdVO4 was conducted by Sulc et al, both in continuous wave (CW) and quasi-continuous wave (QCW) mode. Also, we have previously demonstrated a diode-end-pumped QCW Tm:GdVO4 laser operating at 1818 nm or at 1915 nm by appropriate selection of the resonator output coupling value. Thus, even though significant wavelength tuning has been demonstrated for Tm:GdVO4, to our knowledge, there has been no report of a Tm:GdVO4 laser pumping a Ho 3+ laser. In this paper we report on the design and operation of a diode-end-pumped QCW Tm:GdVO4 laser selected to lase at 1892 nm, which was used to pump a Qswitched Ho:YLF laser. SPECTRAL ANALYSIS To design a high-power diode-pumped Tm:GdVO4 laser for pumping a Ho:YLF laser, detailed spectroscopic studies of the laser materials are required. The absorption cross section data (σabs) of Ho:YLF for the I8 – I7 transition is shown in Figure 1. The absorption is highly polarised and it would be preferential to pump on either of the two absorption peaks of the π-polarisation (E||c), located at 1892 nm (0.72 x 10 cm), and at 1940 nm (0.99 x 10 cm). When pumped at either of these two wavelengths, the Ho:YLF laser can emit at 2.05 μm, (on π-polarisation) or at 2.06 μm when forced to lase on the weaker σ-polarisation (E⊥c). 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.
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