Observation of Laser Oscillation from CaGa ₂S ₄:Eu ²⁺

Abstract

The first observation of laser oscillation from a single crystal of CaGa2S4:Eu2+ (1 at%) is described in this report. A liquid nitrogen cooled thin platelet (0.8 mm thick), whose one flat surface was coated with aluminum to increase the reflectivity, was excited from the other uncoated side with a pulsed dye laser beam having a photon energy of around 2.48 eV. When the input power density exceeded a threshold value of ∼10 MW/cm2, a directional beam having a sharp spectral line at around 2.19 eV emerged from the sample. This laser was found to have interesting wavelength tunability extending to ∼200 Å, possibly related to the broad gain spectrum of Eu2+ emission in this material.

Laser crystals and ceramics: recent advances

“…Many scientists believe that Yb 3+ lasants, due to their small 'quantum defect' (the energy difference between their generation and excitation transitions), which means that little pump power is lost as heat, will (Fig. 10) [209]. Unfortunately, this paper contains no additional explanatory spectroscopic information.…”

Photoconductivity of CaGa 2 S 4 single crystals doped with Eu 2+ and Ce 3+

“…In this group, calcium-thiogallates (CaGa 2 S 4 ) have been regarded as new materials for thin-film displays and lasers [2][3][4]. Owing to the large band gap of CaGa 2 S 4 (E g = 4.1-4.2 eV), the compounds doped with REE gave us large variety in luminescence.…”

Electronic states of lanthanides in the ternary thiogallate CaGa 2 S 4 in view of relativistic first principle calculation

“…The LS coupling of the 4f orbitals does not always result in the discrete level splitting as the j = 5/2 and 7/2 states. Both of these states are partially degenerated to make some molecular orbitals.1 Introduction The ternary thiogallate CaGa 2 S 4 doped with lanthanide elements (CaGa 2 S 4 :Ln) are promising for optoelectronic devices such as wavelength-tuneable light emitters with the laser oscillation [1][2][3][4]. However, the detailed optoelectronic mechanism has been little known especially on the spin properties of 4f electrons of the Ln atoms.…”