Rare-earth doped mixed sesquioxides for ultrafast lasers [Invited]

Abstract

Sesquioxides are outstanding host materials for rare-earth doped laser gain media. Unfortunately, their very high melting points make it challenging for them to be fabricated in high quality. Recently, we demonstrated that some mixed sesquioxides exhibit significantly reduced melting temperatures compared to their constituents. This enables their growth by the established Czochralski method yielding rare-earth doped mixed sesquioxides of high optical quality. Due to their inhomogeneously broadened gain spectra caused by the intrinsic disorder, mixed sesquioxides are very promising for the generation and amplification of ultrashort pulses. To envisage the potential of this emerging class of gain materials, this paper reviews the spectroscopic as well as continuous wave and pulsed laser properties of crystalline and ceramic rare-earth doped mixed cubic sesquioxides of the form (Scx,Luy,Yz)2O3 with x + y + z = 1.

Exploration of the Crystal Growth and Crystal-Field Effect of Yb3+ in Orthorhombic GdScO3 and LaLuO3 Crystals

“…Similarly, solid solution mixing is also a feasible strategy in Yb 3+ -doped rare-earth sesquioxides for spectral broadening. , The mixed sesquioxide hosts can yield two types of crystalline phases (cubic and orthorhombic) due to the differences in cationic radii. − When the difference in cationic radii is small (atomic number Z = 21 (Sc), Z = 39 (Y), and Z = 65 (Tb) to 71 (Lu)), , the obtained mixed rare-earth sesquioxides generally belong to the cubic phase ( Ia 3̅). , As the cationic radii between different rare-earth sesquioxides become large, the orthorhombic solid solution with the space group of Pnma would be formed . For the cubic-phase mixing of rare-earth sesquioxides, mixing RE 2 O 3 (RE = Lu, Y, Sc) hosts attracts wide research attention because there is no absorption from the visible to infrared wavebands.…”

“…11−14 Similarly, solid solution mixing is also a feasible strategy in Yb 3+ -doped rare-earth sesquioxides for spectral broadening. 15,16 The mixed sesquioxide hosts can yield two types of crystalline phases (cubic and orthorhombic) due to the differences in cationic radii. 17−19 When the difference in cationic radii is small (atomic number Z = 21 (Sc), Z = 39 (Y), and Z = 65 (Tb) to 71 (Lu)), 17,20 the obtained mixed rareearth sesquioxides generally belong to the cubic phase (Ia3̅ ).…”

Investigation of crystal field effects for the spectral broadening of Yb3+-doped LuxY2−xO3 sesquioxide crystals

“…The Yb 3+ -doped sesquioxide solid solutions formed by host mixing are effective for broadening the emission spectra and obtaining short pulse widths. [15][16][17][18][19][20] C. J. Saraceno et al used Yb:Lu 2 O 3 with a full width at half maximum (FWHM) emission spectrum of 13 nm and the mixed sesquioxide Yb:LuScO 3 with an FWHM of 22 nm to generate ultrashort pulses, and achieved shortened pulse durations from 142 fs to 96 fs. 14,21,22 Compared with the Sc 3+ ions, the presence of Y 3+ ions in Yb:Lu 2 O 3 largely retains the thermal characteristic, which is the best among these Yb 3+ -doped sesquioxide solid solutions.…”

Spectroscopy and continuous wave laser operation of Tm3+-doped YScO3 mixed sesquioxide crystal

“…Tm 3+ -doped mixed sesquioxides are attractive gain media for ultrafast 2-Pm lasers due to their superior spectroscopic properties [1]. They exhibit a gain band at the wavelengths exceeding 2000 nm where no water vapor absorption and Tm 3+ reabsorption is low, and their disordered crystal structure leads to broad and flat gain spectra due to inhomogeneous spectral broadening [2].…”