Growth, spectroscopy and first laser operation of monoclinic Ho3+ :MgWO4 crystal

A monoclinic 0.86 at.% Ho3+:MgWO4 crystal is grown by the Top-Seeded-Solution Growth method. Its spectroscopic properties are studied with polarized light for E || a, b, c. The Ho3+ ion transition probabilities are determined within the modified Judd-Ofelt theory (mJ-O) accounting for the configuration interaction. The intensity parameters are Ω2 = 21.09, Ω4 = 4.42, Ω6 = 2.28 [10–20 cm2] and α= 0.053 [10-4cm]. The calculated radiative lifetime of the 5I7 state is 6.18 ms. The Stark splitting of the 5I7 and 5I8 multiplets is determined with low-temperature spectroscopy. The absorption, stimulated-emission (SE) and gain cross-sections for the 5I8↔5I7 transition are derived. Ho3+ :MgWO4 features a large Stark splitting of the ground-state (380 cm-1), high maximumσSE of 1.82 × 10–20 cm2 at 2.083μm, broad gain spectra and high luminescence quantum yield making it suitable for efficient continuous-wave and mode-locked lasers at∼2.1μm. First laser operation of Ho3+:MgWO4 crystal is demonstrated at 2.104μm reaching a slope efficiency of 72%

Growth, Mechanical, Thermal and Spectral Properties of Cr3+∶MgMoO4 Crystal

This paper reports the growth, mechanical, thermal and spectral properties of Cr3+∶MgMoO4 crystals. The Cr3+∶MgMoO4 crystals with dimensions up to 30 mm×18 mm×14 mm were obtained by TSSG method. The absorption cross-sections of 4A2→4T1 and 4A2→4T2 transitions are 12.94×10−20 cm2 at 493 nm and 7.89×10−20 cm2 at 705 nm for E//Ng, respectively. The Cr3+∶MgMoO4 crystal shows broad band emission extending from 750 nm to 1300 nm with peak at about 705 nm. The emission cross-section with FWHM of 188 nm is 119.88×10−20 cm2 at 963 nm for E//Ng. The investigated results showed that the Cr3+∶MgMoO4 crystal may be regarded as a potential tunable laser gain medium

Thermal, Spectral and Laser Properties of Er3+:Yb3+:GdMgB5O10: A New Crystal for 1.5 μm Lasers

A novel laser crystal of Er3+:Yb3+:GdMgB5O10 with dimension of 26 × 16 × 12 mm3 was grown successfully from K2Mo3O10 flux by the top seeded solution growth method. The thermal diffusivity and specific heat capacity were measured to calculate the thermal conductivity of the crystal. The absorption and fluorescence properties of the crystal at room temperature were investigated in detail. The Judd-Ofelt method was used to analyze the polarized absorption spectra. The emission cross-section of the 4I13/2→4I15/2 transition was calculated by the Füchtbauer-Ladenburg formula and the relevant gain cross-sections were estimated. Continuous-wave laser output of 140 mW at 1569 nm with the slope efficiency of 17.8% was demonstrated in a plano-concave resonator. The results reveal that Er3+:Yb3+:GdMgB5O10 crystal is a promising material for 1.5 μm lasers

A Switchable Chaotic Oscillator with Multiscale Amplitude/Frequency Control

For the wide frequency spectrum of chaotic signals, it is difficult to realize chaotic signal conditioning. Therefore, researchers turn to the exploration of chaotic systems with independent non-bifurcation control for easy chaos modification. In this paper, a system with only one non-quadratic term is modified for providing multiscale amplitude/frequency control. By adjusting the feedback with an odd higher degree term, a switchable chaotic oscillator is obtained, which provides the different scales of amplitude/frequency control with the chaotic signal. Multisim-based circuit simulation shows the efficiency and convenience of chaotic signal control

Growth, thermal and spectral properties of Er3+-doped and Er3+/Yb3+-codoped Li3Ba2La3(WO4)8 crystals.

This paper reports the growth and spectral properties of Er(3+)-doped and Er(3+)/Yb(3+)-codoped Li(3)Ba(2)La(3)(WO(4))(8) crystals. The Er(3+): Li(3)Ba(2)La(3)(WO(4))(8) crystal with dimensions of 56 mm × 28 mm × 9 mm and Er(3+)/Yb(3+): Li(3)Ba(2)La(3)(WO(4))(8) crystal with dimensions of 52 mm × 24 mm × 8 mm were obtained by the top-seeded solution growth (TSSG) method. Thermal expansion coefficients and thermal conductivity of both crystals were measured. The spectroscopic characterizations of both crystals were investigated. The spectroscopic analysis reveals that the Er(3+)/Yb(3+): Li(3)Ba(2)La(3)(WO(4))(8) crystal has much better optical properties than the Er(3+): Li(3)Ba(2)La(3)(WO(4))(8) crystal, thus it may become a potential candidate for solid-state laser gain medium material

Optical study of Cr3+-doped LaSc3(BO3)(4) crystal

This paper reports on the optical properties of Cr3+-doped LaSc3(BO3)(4) (Cr3+:LSB). Based on measurement of the absorption spectrum the crystal field strength Dq, the Racah parameters B and C were calculated. The photoluminescence spectrum of Cr3+:LSB via T-4(2) -->(4)A(2) transition is a broadband emission from 740 to 1280 nm at room temperature. The measurements of absorption and photoluminescence spectra show that in Cr3+:LSB the Cr3+ ions occupy weak crystal field sites

Crystal growth and optical assessment of Nd3+ : GdAl3(BO3)4 crystal

This paper reports the high-temperature top-seeded solution growth (TSSG) of large single crystal of Nd3+-doped GdAl3(BO3)4 from a K2Mo3O10-LiF flux cooled at a rate of 2 K/day and using a crystal rotation rate of 4.5 rpm. Thepolarized optical absorption and fluorescence spectra of Nd3+ : GdAl3(BO3)4 crystal have been investigated. Polarized absorption cross sections are 4.3x10-20 and 2.6x10-20 cm2 with band widths of 8.7 and 6.1 nm for σ- and π-polarization, respectively. The emission cross sections are 6.3x10-19 and 6.0x10-19 cm2 for σ- and π-polarization, respectively, at 1062 nm corresponding to the 4F3/2→4I11/2 transition. The fluorescence lifetime is 54.3 and 57 μs at 300 and 20 K, respectively

Continuous-wave and SESAM mode-locked femtosecond operation of a Yb:MgWO4laser

We present a detailed continuous-wave regime characterization and, for the first time to the best of our knowledge, SESAM mode-locked femtosecond operation with a monoclinic, Yb3+-doped, MgWO4 crystal. Pumping with a low-power, single-mode fiber-coupled laser diode emitting at 976 nm, we demonstrate threshold for continuous-wave (cw) operation as low as 50 mW (absorbed pump power) and slope efficiency up to ~60% (with respect to the absorbed pump power) for two of the principal emission polarizations. The output wavelength in the cw regime is continuously tunable over a ∼50 nm broad range. Mode-locking the laser with a SESAM, we achieve almost Fourier-transform limited pulses with a duration of 132 and 125 fs depending on the polarization