2.8-µm polarization-maintaining Er fiber laser mode-locked by a GaSb-based SESAM.

A GaSb-based SEmiconductor Saturable Absorber Mirror (SESAM) enables continuous-wave picosecond mode-locked operation with excellent stability of a polarization-maintaining mid-infrared Er:ZBLAN fiber laser. The GaSb-based SESAM mode-locked fiber laser delivers an average output power of 190 mW at 2.76 µm at a repetition rate of 32.

Upconversion-pumped femtosecond thulium laser at 2309 nm mode-locked by a GaSb-based SESAM.

We report on a femtosecond thulium laser operating on the H → H transition with upconversion pumping around 1 µm and passively mode-locked by a GaSb-based SEmiconductor Saturable Absorber Mirror (SESAM). This laser employs a 6 at.% Tm:LiYF laser crystal and a polarization maintaining Yb-fiber master oscillator power amplifier at 1043 nm as a pump source addressing the F → F excited-state absorption transition of Tm ions.

High-power 2.3 µm Tm:YLF laser with intracavity upconversion pumping by a Nd:ASL laser at 1051 nm.

A Tm:LiYF laser operating on the H→ H transition is embedded in a high-power diode-pumped Nd:ASL laser for intracavity upconversion pumping at 1.05 µm. This leads to a record-high output power at 2.

Cascade laser optimization for H → H and F → H sequent transitions in Tm-doped materials.

We study a cascade laser scheme involving the H → H and F → H consecutive transitions in Tm-doped materials as a promising technique to favor laser emission at 2.3 µm. We examine the conditions in terms of the Tm doping levels for which the cascade laser is beneficial or not.

Tm:CALGO lasers at 2.32 µm: cascade lasing and upconversion pumping.

We report on the first laser operation of a disordered Tm:CaGdAlO crystal on the H → H transition. Under direct pumping at 0.79 µm, it generates 264 mW at 2.

Excited-state absorption and upconversion pumping of Tm-doped potassium lutetium double tungstate.

We report on a bulk thulium laser operating on the H → H transition with pure upconversion pumping at 1064 nm by an ytterbium fiber laser (addressing the F → F excited-state absorption (ESA) transition of Tm ions) generating 433 mW at 2291 nm with a slope efficiency of 7.4% / 33.2% vs.

Dual-wavelength-pumping of mid-infrared Tm:YLF laser at 2.3 µm: demonstration of pump seeding and recycling processes.

Upconversion pumping of thulium lasers emitting around 2.3 µm (the H → H transition) has recently attracted a lot of attention as it is compatible with the mature Yb-laser technology. To explore this possibility, we built a mid-infrared Tm:LiYF laser pumped by an Yb:CaF laser at 1.

Excited-state absorption in thulium-doped materials in the near-infrared.

Excited-state absorption (ESA) is a key process for upconversion pumping schemes of thulium (Tm) doped laser materials. We have systematically studied two ESA transitions in the near-infrared spectral range, namely F → F (at ∼1 µm) and F → H (at ∼1.5 µm), in various Tm-doped fluoride (ZBLAN glass, cubic KYF and CaF, tetragonal LiYF and LiLuF, monoclinic BaYF crystals) and oxide (cubic YAlO, orthorhombic YAlO crystals) laser materials, using a pump-probe method with a polarized light.

Watt-level efficient 2.3 µm thulium fluoride fiber laser.

We report on an efficient mid-infrared thulium (Tm) fiber laser operating on the → transition and featuring an upconversion pumping scheme. This laser comprises a heavily -doped (2.50 mol.

Channel waveguide lasers in bulk Tm:LiYF produced by deep diamond-saw dicing.

We report on a novel approach to fabricate channel (ridge) waveguides (WGs) in bulk crystals using precision diamond saw dicing. The channels feature a high depth-to-width aspect ratio (deep dicing). The proof-of-the-concept is shown for a Tm:LiYF fluoride crystal.

Watt-level diode-pumped thulium lasers around 2.3 µm.

We report on efficient diode-pumped mid-infrared lasers based on :, :, and : crystals. These lasers operate in the continuous-wave (CW) regime and deliver watt-level output power at the wavelengths of 2.2-2.

Close look on cubic Tm:KYF crystal for highly efficient lasing on the H → H transition.

We report on Czochralski growth, detailed ground- and excited-state absorption and emission spectroscopy and highly-efficient mid-infrared (∼2.3 µm) laser operation of a cubic potassium yttrium fluoride crystal, Tm:KYF. The peak stimulated-emission cross-section for the H → H transition is 0.

Continuous-wave Tm:YAlO laser at ∼2.3 μm.

The orthorhombic Tm:YAlO crystal is promising for laser operation at the H3→F3 (1.5 μm) and H3→H3 (2.3 μm) transitions.

Thulium laser at ∼2.3 μm based on upconversion pumping.

We report on novel upconversion (UC) pumping schemes for 2.3 μm thulium (Tm) lasers (the H3→H3 transition) based on a photon avalanche mechanism populating the intermediate metastable level (F3) acting as an effective ground state. The proposed pump wavelengths are ∼1 and ∼1.

In-band pumping of Tm:LiYF channel waveguide: a power scaling strategy for ∼2 μm waveguide lasers.

We report on a novel power scaling strategy for thulium waveguide (WG) lasers relying on in-band pumping by high-brightness Raman fiber lasers (RFLs) and the use of liquid-phase-epitaxy-grown fluoride crystalline thin films for better thermal management. Thulium channel WGs are produced by microstructuring the Tm:LiYF/LiYF epitaxies via diamond-saw dicing. They are pumped by a RFL based on an erbium master oscillator power amplifier and a GeO-doped silica fiber and emit polarized output at 1679 nm.

Ytterbium calcium fluoride waveguide laser.

Calcium fluoride is a well-known material for optical components. It is also suited for doping with rare-earth ions, e.g.

Laser operation of highly-doped Tm:LiYF epitaxies: towards thin-disk lasers.

Quasi-continuous-wave laser operation of 20 at.% Tm:LiYF thin films (84-240 μm) grown by Liquid Phase Epitaxy (LPE) on undoped LiYF substrates is achieved. The 240 μm-thick Tm:LiYF active layer pumped at 793 nm with a simple double-pass scheme generated 152 mW (average power) at 1.