The Yb3+:LuAlO3 crystal as an active medium for picosecond mode-locked lasers

Herein, we report on the mathematical modelling and experimental study of the regime of nonsoliton mode locking in a laser based on the Yb3+:LuAlO3 (Yb:LuAP) crystal with longitudinal pumping by laser diode radiation. Simulation based on the Haus master equation permitted to determine the requirements for the parameters of a saturable absorber (SA), the level of the average output power, the size of the TEM00 mode of the cavity in the active element and on the gate to obtain a stable regime of generation of picosecond laser pulses. Laser experiments were carried out in a fourmirror X-shaped resonator using a semiconductor saturable mirror (SESAM) as a passive modulator and a laser diode with a fiber output of a maximum power up to 30 W at a wavelength of 978.5 nm as a pump source. We obtained a stable passive mode locking with a maximum average output power of up to 12 W and an ultrashort pulse duration of about 2 ps at an optical conversion efficiency of pump radiation into lasing radiation of about 38 %. Laser pulses were obtained at a central wavelength of about 999 nm with a minimum Stokes shift (about 2 %) with respect to the pump radiation, which significantly reduced the thermal load on the active element. Additionally, the preliminary results on the second harmonic generation and synchronous pumping of a parametric light generator using a Yb3+ : LuAlO3 crystal laser as a pump source are presented.

Active glasses as the luminescent sources of radiation for sensor applications

The article presents physicochemical, thermal and spectroscopic properties of two different glass systems: TeO2-GeO2-PbO-PbF2- BaO-Nb2O5-LaF3 and SiO2-Al2O3-Sb2O3, co-doped with Yb3+/Tm3+ ions. Blue upconversion luminescence at a wavelength of 478 nm corresponding to the thulium 1G4 ⇥3H6 transition was observed under 976 nm pump radiation in both of the co-doped glasses. This indicated the existence of efficient Yb3+ ⇥ Tm3+ energy transfer via three-photon absorption mechanism. Thermal and optical results substantiate the claim for practical applicability of the manufactured glasses in design of optical fiber sources.

Upconversion of Broadband Infrared Radiation into Visible Light for Different Pumping Parameters

The influence of pump radiation parameters such as the polarization and the spectral width of infrared radiation on the conversion of broadband radiation in lithium niobate crystals was investigated. The spectra of converted radiation were calculated for two types of phase matching in the negative uniaxial crystal by taking into account the convergence of the light beam in the crystal. Experimental spectra were obtained and compared with the calculated spectra.