CdGeP 2 is a non-centrosymmetric uniaxial crystal whose birefringence is too low for phase-matching in its transparency range; however, it has been successfully applied in THz generation using near-IR laser pump sources. We present measurements of the linear thermal expansion of CdGeP 2 in the 12-820 K temperature range by X-ray diffraction using powdered samples. The results indicate strong anisotropy with negligible compression along the optical axis.

Two-photon absorption (TPA) measurements are performed on Ge using an open-aperture z-scan setup with 2.05 & micro;m, 0.57 ps pulses from a Ho:YLF regenerative amplifier to resolve discrepancy issues from previous studies using different methods. Uncoated and antireflection-coated Ge samples are compared. The derived TPA coefficient at low intensity is determined to be (40 +/- 8) cm/GW while the weak trend of decreasing TPA with intensity is likely due to saturation. Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

We review our recent achievements with narrowband, nanosecond, non-resonant optical parametric oscillators based on periodically-poled LiNbO 3 , which are pumped at 1064 nm and emit close to degeneracy in the near-IR part of the spectrum between 1860 and 2486 nm. The average output power has been scaled up to the 10-W level with tuning across 40 nm (signal) and 66 nm (idler) using transversely chirped volume Bragg gratings (VBGs) acting on the signal wave. The maximum total average output power (signal + idler) achieved with a narrowband VBG has reached 11.35 W at 20 kHz, corresponding to a conversion efficiency of 63%. In this case, the signal and idler bandwidths amount to 0.7 and 0.9 nm at ~1922 and ~2384 nm, respectively. The experimentally observed spectral narrowing is reproduced by numerical simulations based on a split-step method within the plane-wave approximation taking account pump depletion and back-conversion. Spatial effects are also incorporated in the model, taking into account the transversal intensity distributions, in order to better reproduce the input-output power characteristics.

We report on sub-50 fs pulse generation from a diode-pumped mode-locked laser based on an ytterbium-doped monoclinic potassium yttrium double tungstate crystal operating in the 1 mu m spectral region. Pumping by a low-power, spatially single-mode, fiber-coupled laser diode at 976 nm, a maximum continuous-wave output power of 433 mW at 1066.1 nm was obtained. Using a quartz-based intracavity Lyot filter, an exceptionally broad continuous-wavelength tuning range of 98 nm was achieved. In the mode-locked regime, the diode-pumped Yb:KY(WO4)2 laser delivered soliton pulses as short as 46 fs at a central wavelength of 1069.2 nm by employing a SEmiconductor Saturable Absorber Mirror. To the best of our knowledge, these results represent the broadest continuous-wave tuning range and the shortest pulse duration ever reported for lasers based on ytterbium-doped monoclinic double tungstate crystals.

We report on continuous-wave and passively mode-locked operation of a diode-pumped Yb:Ca3TaGa3Si2O14 laser. In the continuous-wave regime, the laser delivered a maximum output power of 408 mW at 1045.5 nm, corresponding to a slope efficiency of 58.1% and a laser efficiency of 53.4%. By incorporating a quartz-based Lyot filter, a continuous wavelength tuning range of 82 nm, spanning from 1007 to 1089 nm, was achieved. In the mode-locked regime, a commercial semiconductor saturable absorber mirror was employed to initiate and sustain soliton-like pulse shaping, and pulses as short as 50 fs were generated at a central wavelength of 1052.4 nm, with an average output power of 40 mW at a pulse repetition rate of 73.9 MHz. To the best of our knowledge, this is the first demonstration of a mode-locked laser based on the Yb:Ca3TaGa3Si2O14 langasite-type non-centrosymmetric crystal, highlighting its significant potential as a gain medium for sub-100 fs solid-state lasers.

We report on an Yb:YAB laser pumped by a spatially single-mode, low-power, fiber-coupled InGaAs laser diode at 976 nm, delivering soliton pulses as short as 36 fs at 1059.7 nm via soft-aperture Kerr-lens mode-locking. The average output power amounts to 156 mW at a pulse repetition rate of ∼66.7 MHz. To the best of our knowledge, this represents the first demonstration of Kerr-lens mode-locked operation with the Yb:YAB crystal, and the shortest pulses ever achieved from an Yb:YAB laser.

We report experimental results on the temperature-dependent phase-matching properties of AgGa1-xInxSe2 with x = 0.315 for type-1 second-harmonic and sum-frequency generation in the 2.200-10.5910 & micro;m range. From these data, we derived a thermo-optic dispersion formula for x = 0.315. Using our recently published formula for AgGaSe2 (x = 0), we further extrapolated a companion formula for AgInSe2 (x =1) based on the standard interpolation of the linear susceptibility in the mixed chalcopyrite. The validity of this new set of index dispersion formulas was confirmed by reproducing earlier experimental results on temperature-tuned, type-1 cascade third-harmonic generation of a CO2 laser in AgGa1-xInxSe2 with x = 0.474, under angular noncritical phase-matching conditions.

We report on the growth of high-quality Er 3+ :MgWO 4 single crystals from the flux using K 2 W 2 O 7 as a solvent and the polarized spectroscopy in the dielectric frame, including absorption, luminescence and gain cross sections.

We report experimental results on the temperature-dependent phase-matching properties of AgGa 1- x In x Se 2 with x = 0.315 for type-1 second-harmonic and sum-frequency generation in the 2.200–10.5910 µm range. From these data, we derived a thermo-optic dispersion formula for x = 0.315. Using our recently published formula for AgGaSe 2 ( x = 0), we further extrapolated a companion formula for AgInSe 2 ( x = 1) based on the standard interpolation of the linear susceptibility in the mixed chalcopyrite. The validity of this new set of index dispersion formulas was confirmed by reproducing earlier experimental results on temperature-tuned, type-1 cascade third-harmonic generation of a CO 2 laser in AgGa 1- x In x Se 2 with x = 0.474, under angular noncritical phase-matching conditions.

We report on a diode-pumped SESAM mode-locked Yb:Ca 3 TaGa 3 Si 2 O 14 laser generating soliton pulses as short as 50 fs at 1052.4 nm with an average output power of 40 mW at ~74 MHz.

We report the linear and nonlinear optical properties of Te1-chi Se chi for second-harmonic generation (SHG) of a CO2 laser at 10.5910 mu m. Calculations based on the published nonlinear optical coefficients of Te (chi = 0) and Se (chi = 1), together with the phase-matching properties obtained from our Sellmeier equations, reveal that a mixed Te1-chi Se chi crystal with a nominal Se content of chi = 0.34 enables efficient type-2 phase matching for generating high-peak-power SHG at 5.2955 mu m. This is primarily due to the composition being free from the deleterious effects of multiphoton absorption (2 omega + 2 omega and omega + 2 omega) and free-carrier generation, which are inherent to pure Te.

Linear thermal expansion in the 76-310 K range, and nanohardness and Young’s modulus at room temperature are measured for the newly developed quaternary nonlinear optical crystal Ba 2 Ga 8 GeS 16 with hexagonal symmetry, applicable in the mid-IR part of the spectrum. The results reveal quasi-isotropic behavior of all these properties.

We report on the passively mode-locked operation of an Yb:SrF 2 laser generating sub-40 fs pulses at ∼1 μm. By using a high-brightness Yb-fiber laser as the pump source, the Yb:SrF 2 laser delivered soliton pulses as short as 37 fs at 1066.4 nm via soft-aperture Kerr-lens mode-locking, with an average output power of 85 mW at a pulse repetition rate of ∼71.8 MHz. To the best of our knowledge, this is the first demonstration of Kerr-lens mode-locking using the Yb:SrF 2 crystal.

We report on continuous-wave and passively mode-locked operation of a diode-pumped Yb:Ca 3 TaGa 3 Si 2 O 14 laser. In the continuous-wave regime, the laser delivered a maximum output power of 408 mW at 1045.5 nm, corresponding to a slope efficiency of 58.1% and a laser efficiency of 53.4%. By incorporating a quartz-based Lyot filter, a continuous wavelength tuning range of 82 nm, spanning from 1007 to 1089 nm, was achieved. In the mode-locked regime, a commercial semiconductor saturable absorber mirror was employed to initiate and sustain soliton-like pulse shaping, and pulses as short as 50 fs were generated at a central wavelength of 1052.4 nm, with an average output power of 40 mW at a pulse repetition rate of 73.9 MHz. To the best of our knowledge, this is the first demonstration of a mode-locked laser based on the Yb:Ca 3 TaGa 3 Si 2 O 14 langasite-type non-centrosymmetric crystal, highlighting its significant potential as a gain medium for sub-100 fs solid-state lasers.

CdGeP2 is a non-centrosymmetric uniaxial crystal whose birefringence is too low for phase-matching in its transparency range; however, it has been successfully applied in THz generation using near-IR laser pump sources. We present measurements of the linear thermal expansion of CdGeP2 in the 12-820 K temperature range by X-ray diffraction using powdered samples. The results indicate strong anisotropy with negligible compression along the optical axis.

Linear thermal expansion in the 76-310 K range, and nanohardness and Young's modulus at room temperature are measured for the newly developed quaternary nonlinear optical crystal Ba2Ga8GeS16 with hexagonal symmetry, applicable in the mid-IR part of the spectrum. The results reveal quasi-isotropic behavior of all these properties. Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.