Tm,Ho:Ca(Gd,Lu)AlO4 crystals: Crystal growth, structure refinement and Judd-Ofelt analysis

“Mixed” calcium rare-earth aluminate laser host crystals Ca(Gd,Lu)AlO4 (CALGLO) with up to 10.8 at.% Lu codoped with Tm3 + and Ho3 + ions are grown by the Czochralski method along the [001] direction. The segregation of rare-earth ions is studied. The crystal structure is refined by the Rietveld method. Tm,Ho:Ca(Gd, Lu)AlO4 crystallizes in the tetragonal system (sp. gr. I4/mmm) exhibiting a K2NiF4 type structure. The lattice constants are a = 3.6585(6) Å and c = 11.9660(9) Å for a crystal with a composition of CaG-d0.8947Lu0.0551Tm0.0448Ho0.0054AlO4. The stability of Ca(Gd,Lu)AlO4 solid-solutions is discussed. The polarized Raman spectra are measured, revealing a most intense mode at 311 cm 1 and a maximum phonon frequency of ~650 cm 1. The polarized absorption spectra are measured. The transition intensities for the Ho3 + ion are analyzed using the modified Judd-Ofelt theory accounting for configuration interaction

Evaluation of Growth, Thermal, and Spectroscopic Properties of Er3+-Doped CLNGG Crystals for Use in 2.7 μm Laser

A series of optical-quality Er3+-doped calcium lithium niobium gallium garnet (CLNGG) single crystals with different Er3+ ion concentration (10, 15 and 30 at.%) has been grown by the Czochralski method. A comparative study of their structure, thermal, and spectroscopic properties is performed. Crystal structure was analyzed with X-ray powder diffraction (XRPD) and refined by the Rietveld method, results showing that the Er:CLNGG crystal possesses a cubic structure with space group Ia3¯d, and the lattice constants decrease linearly as the Er3+ concentration increase. The complete set of thermal properties were systematically studied for the first time. It has been found that all the thermal conductivities increase with temperature, indicating a glass-like behavior. Effect of Er3+ concentration on spectroscopic properties of Er:CLNGG crystals was studied. Results show that with the Er3+ concentration increase, the NIR fluorescence around 1600 nm weakens, while the Mid-IR fluorescence intensity around 2700 nm strengthens. Fluorescence lifetime of 4I13/2 decreased faster than that of 4I11/2 with the Er3+ concentration increase, which is beneficial for surmounting the “bottleneck” effect to achieve 2.7 μm laser. All the results show that CLNGG crystal with high Er3+ concentration is a potential candidate for the 2.7 μm laser

Recent advances in self-frequency-doubling crystals

The self-frequency-doubling (SFD) crystal is a representative of multifunctional crystals. In recent years, SFD crystals and lasers have gained renewed attention based on the progress on SFD crystals and lasers and Nd:RECa4O(BO3)3 (RE = Y or Gd) crystals, with SFD lasers becoming commercial products. Here, we review the advances of SFD crystals and lasers, including the basic selection rules, theoretical analysis and recent progress of some potential SFD crystals and lasers. The Nd:RECa4O(BO3)3 crystals and lasers are highlighted, and their applications are also proposed and discussed, which may provide some inspiration for the further development of the SFD field and multifunctional materials

Nonlinear optical properties of carboxyl-functionalized graphene oxide for dissipative soliton resonance pulse generation

Here, we investigated the nonlinear optical (NLO) characteristics of carboxyl-functionalized graphene oxide (GO-COOH) in the near-infrared (NIR) region. The results revealed that GO-COOH samples exhibit strong saturable absorption at low pump levels and a gradual transition to reverse saturable absorption (RSA) with increasing pump power. Then the saturable absorber (SA) by depositing the GO-COOH on the side-polished fiber (SPF) was employed in Yb- and Er-doped fiber lasers. Stable ultrashort pulses operating in the dissipative soliton (DS) and conventional soliton (CS) regimes were obtained with pulse widths of 26.6 ps and 968 fs, respectively. Besides, the dissipative soliton resonance (DSR) phenomenon caused by the RSA of GO-COOH was also observed with increasing pump power. The high-stable DSR mode-locked pulses with the maximum pulse energy of 1.91 nJ and 0.74 nJ were obtained in YDFL and EDFL respectively. These results not only reveal the potentiality of GO-COOH in ultrafast photonics applications but also open a new avenue to explore high-pulse-energy laser sources based on two-dimensional materials

Compact diode-pumped continuous wave and passively Q switched Tm:YAG laser at 2.33 µm

Compact diode-pumped continuous wave (CW) and passively Q switched Tm:YAG lasers operating on the 3 H 4 → 3 H 5 transition are demonstrated. Using a 3.5-at.% Tm:YAG crystal, a maximum CW output power of 1.49 W is achieved at 2330 nm with a slope efficiency of 10.1%. The first Q switched operation of the mid-infrared Tm:YAG laser around 2.3 µm is realized with a few-atomic-layer MoS 2 saturable absorber. Pulses as short as 150 ns are generated at a repetition rate of 190 kHz, corresponding to a pulse energy of 1.07 µJ. Tm:YAG is an attractive material for diode-pumped CW and pulsed mid-infrared lasers emitting around 2.3 µm

Mid-Infrared Laser Emissions of Tm 3+ -doped Garnets: The Case Study of Disordered Tm:CNGG Crystal

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Sub-100 fs mode-locked Tm:CLTGG laser

We report on the first sub-100 fs mode-locked laser operation of a Tm3+-doped disordered calcium lithium tantalum gallium garnet (Tm:CLTGG) crystal. Soliton mode-locking was initiated and stabilized by a transmission-type single-walled carbon nanotube saturable absorber. Pulses as short as 69 fs were achieved at a central wavelength of 2010.4 nm with an average power of 28 mW at a pulse repetition rate of ∼87.7 MHz. In the sub-100 fs regime, the maximum average output power amounted to 103 mW

Sub-50-fs SESAM mode-locked Tm,Ho:Ca(Gd,Lu)AlO4 laser

International audienc

Sub-100 fs mode-locked Tm:CLTGG laser

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