Martin Thalbitzer Andersen

Red-IR stimulated luminescence in K-feldspar: Single or multiple trap origin?

We investigate on the origins of the infra-red stimulated luminescence (IRSL) signals in 3 potassium feldspars based on IR-red spectroscopy (∼700–1050 nm) using a fiber-coupled tunable Ti:Sapphire laser, in combination with different thermal and optical (pre)treatments of the samples. We also measure dose-response curves with different wavelengths and at different stimulation temperatures so as to be able to distinguish between traps based on their electron trapping cross-sections. Our data suggest that the dosimetric signals, IRSL, and the post IR-IRSL in K-feldspars arise from a single electron trapping centre.

Efficient visible light generation by mixing of a solid-state laser and a tapered diode laser

A generic approach to efficient visible light generation based on singly-resonant sum-frequency mixing of an external-cavity tapered diode laser and a diode pumped solid-state laser is presented. The principle is exemplified by generation of more than 300 mW of 488 nm coherent blue light by mixing of a 950 mW beam from an external-cavity 765 nm tapered diode laser with the intra-cavity field of a diode pumped, high finesse 1342 nm solid-state laser using periodically poled KTP as the nonlinear medium. Using this approach, a conversion efficiency of more than 30 % of the 765 nm beam was obtained.

First measurement of the nonlinear coefficient for Gd(1-X)Lu(X)Ca(4)O(BO(3))(3) and Gd(1-X)Sc(X)Ca(4)O(BO(3))(3) crystals.

The effective nonlinear coefficient and temperature acceptance bandwidth of three Lu and Sc co-doped GdCa(4)O(BO(3))(3) type nonlinear crystals were measured. NCPM for SHG in to the blue-UV spectral region can be obtained by controlling the co-dopant concentration. Measurements were based on intra-cavity SHG of a CW Ti:Sapphire laser, and the effective nonlinear coefficients were found to be in the range of 0.5 to 0.6 pm/V for the three crystals used. The FWHM temperature acceptance bandwidth was measured to be more than 35 degrees C using a 6 mm long Gd(0.871)Lu(0.129)Ca(4)O(BO(3))(3) crystal. A maximum of 115 mW at 407.3 nm in a single direction was measured using a 6.5 mm long Gd0.96Sc0.04Ca(4)O(BO(3))(3) crystal.

Singly-resonant sum frequency generation of visible light in a semiconductor disk laser

In this paper a generic approach for visible light generation is presented. It is based on sum frequency generation between a semiconductor disk laser and a solid-state laser, where the frequency mixing is achieved within the cavity of the semiconductor disk laser using a single-pass of the solid-state laser light. This exploits the good beam quality and high intra-cavity power present in the semiconductor disk laser to achieve high conversion efficiency. Combining sum frequency mixing and semiconductor disk lasers in this manner allows in principle for generation of any wavelength within the visible spectrum, by appropriate choice of semiconductor material and single-pass laser wavelength.

Nonlinear cavity dumping of a high finesse frequency mixing module

We present a novel generic approach for pulsed light generation in the visible spectrum. We demonstrate how the circulating field of a high finesse laser can be efficiently cavity dumped through sum-frequency mixing with externally injected high peak power single pass pulses. Periodically poled KTP is used as the nonlinear medium to minimize the peak power requirement of the injected beam. The experimental setup consists of a high finesse 1342 nm Nd:YVO4 laser cavity and a passively Qswitched Nd:YAG laser. Yellow pulses at 593 nm are generated.

300 mW of coherent light at 488 nm using a generic approach

We present a generic approach for efficient generation of CW light with a predetermined wavelength within the visible or UV spectrum. Based on sum-frequency generation (SFG), the circulating intra-cavity field of a high-finesse diode pumped CW solid-state laser (DPSSL) and the output from a tapered, single-frequency external cavity diode laser (ECDL) are mixed inside a 10 mm periodically poled KTP crstal (pp-KTP). The pp-KTP is situated inside the DPSSL cavity to enhance conversion efficiency of the nonlinear mixing process. This approach combines different solid state technologies; the tuneability of ECDLs, the high intra-cavity filed of DPSSLs and flexible quasi phase matching in pp-tapered ECDL with a center wavelength of 766 nm in combination with a high finesse Nd:YVo4 laser at 1342 nm. Up to 308 mW of light at 488nm was measured in our experiments. The conversion of te ECDL beam was up to 47% after it was transmitted through a PM fiber, and up to 32% without fiber coupling. Replacing the seed laser and the nonlinear crystal makes it possible to generate light at virtually any desired wavelength withing the visible spectrum.

Intracavity Frequency Mixing in a Semiconductor Disk Laser Generating >100mW in the Yellow-Orange

More than 100mW of ~593nm continuous wave output was generated by mixing the 980mW beam from a 1342nm Nd:YVO4laser with the intracavity beam of an InGaAs semiconductor disk laser with centre wavelength ~1064nm.

Comparison of a Ti:S Laser and a Tapered External Cavity Diode Laser for Sum Frequency Generation in a High-Finesse 1342 nm Nd:YVO 4 Laser

Using a Brewster cut periodically poled KTP crystal intra-cavity in a high finesse diode pumped CW 1342 nm laser, efficient sum-frequency generation is obtained by single passing a 765 nm beam from a Ti:Sapphire ring-laser.