Laser Operation Of Nd Research Articles

Tunable continuous-wave laser operation of Nd:YAG around 1.3 μm

A tunable continuous-wave (cw) Nd:YAG laser using a birefringent filter (BF) was performed at six different laser wavelengths of 1319, 1334, 1338, 1341, 1353 and 1356 nm based on the 4F3/2–4I13/2 transition. A highest output power of 4.64 W was achieved at an emission wavelength of 1319 nm with a slope efficiency of 29.8% with respect to the absorbed pump power. Moreover, by adjusting the rotation angle of the BF, a cw simultaneous dual-wavelength Nd:YAG laser operating at 1353 and 1356 nm was also demonstrated for the first time. At an absorbed pump power of 17.8 W, the maximum output power obtained at 1353 nm and 1356 nm is 262 mW and 520 mW, respectively.

Passively Q-switched and Q-switched mode-locked Nd:Lu0.15Y0.85VO4 lasers at 1.34 µm with a nickel-cobalt layered double hydroxide saturable absorber

A nickel-cobalt (NiCo) layered double hydroxide (LDH) saturable absorber (SA) was successfully fabricated and utilized as a passively mode-locked (PML) laser modulator for the first time. We successfully investigated a 1.34 µm passively Q-switched (PQS) and Q-switched mode-locked (QML) laser operation of Nd:Lu0.15Y0.85VO4 mixed crystal with NiCo-LDH SA, respectively. A stable pulse sequence with a narrowest pulse width of 52 ns and a repetition frequency of 1.18 MHz was obtained, leading to a single pulse energy of 0.72 µJ. Furthermore, for the QML laser operation, an average power of 1.10 W and a calculated pulse width of 25 ps were gained with a repetition frequency of 134 MHz. The results indicate the NiCo-LDH SA has remarkable nonlinear optical properties and promising application prospects in the field of laser modulators at 1.3 µm.

Spectral properties and laser operation of Nd3+-doped mixed sesquioxide LuYO3 ceramic

The absorption spectrum, fluorescence spectrum and fluorescence time of a mixed sesquioxide Nd:LuYO3 ceramic were measured at room temperature. Judd-Ofelt theory was applied to calculate the spectral parameters of Nd:LuYO3. The absorption cross section at 812 nm was calculated to be 0.99 × 10−20 cm2 with full width at half maximum (FWHM) of 47.69 nm. The emission cross-section at 1077 nm was calculated to be 5.24 × 10−20 cm2 with FWHM of 11.62 nm. The fluorescence lifetime and quantum efficiency of the 4F3/2 multiplet were determined to be 228.4 μs and 85.2%, respectively. Continuous-wave (CW) laser operation of Nd:LuYO3 ceramic was demonstrated. Simultaneous laser operation at 1075.24 and 1080.03 nm was achieved with maximum output power of 490 mW and slope efficiency of 6.36%.

Polarized spectral properties and laser operation of Nd:SrAl12O19 crystal

Nd:SrAl11O19 (Nd:SRA) crystal has been grown by the Czochralski method. Polarized absorption spectra, polarized fluorescence spectra and fluorescence lifetime were investigated. For σ-polarization, the peak absorption cross section at 798 nm is 2.08 × 10−20 cm2 with full width at half maximum (FWHM) of 10.2 nm and the peak emission cross section is 3.36 × 10−20 cm2 at 1048.5 nm with FWHM of 4.80 nm. The Judd-Ofelt parameters Ω2,4,6 were obtained to be 0.51 × 10−20 cm2, 2.08 × 10−20 cm2, and 2.12 × 10−20 cm2, respectively. Continuous-wave laser operation of the a-cut and c-cut Nd:SRA sample has been demonstrated. The maximum output power of 8.33 W was achieved from c-cut sample at an absorbed power of 27.73 W, corresponding to a slope efficiency of 31.3%.

Growth, Characterization, and Efficient Continuous-Wave Laser Operation in Nd,Gd:CaF2 Single-Crystal Fibers

Nd,Gd:CaF2 single-crystal fibers (SCFs) of various Nd3+ and Gd3+ concentrations were grown by a modified temperature gradient technique (TGT) using a home-designed multi-microchannel crucible. Powd...

Femtosecond laser direct writing of few-mode depressed-cladding waveguide lasers.

We report on mirrorless laser operation of Nd:YVO4 single- and double-cladding waveguides fabricated by femtosecond laser direct writing. Fundamental- (LP01) and high-order-mode (LP03, LP05) guiding and lasing have been observed in waveguides with different geometries and sizes. Double-cladding waveguides exhibit good guiding and lasing performance via inheriting advantages respectively from individual single cladding. As a result, continuous-wave lasing with a threshold as low as 59 mW is obtained, depending on the optical feedback provided only by Fresnel reflections at the waveguide end faces. By using few-layer graphene as saturable absorber, passively Q-switched operation in fabricated waveguides is also achieved.

Crystal growth, optical properties and laser performance of new mixed Nd3+ doped Gd0.1Y0.9AlO3 crystal

A Nd3+ doped Gd0.1Y0.9AlO3 crystal was successfully grown using the Czochralski method. The segregation coefficient of Nd3+ ions was found to be as large as 0.76 in Gd0.1Y0.9AlO3 host. Based on the Judd-Ofelt theory, the three intensity parameters Ω2,4,6, radiative lifetimes, branching ratios were calculated to analyze the absorption and emission properties of the as-grown crystal. It is found that the width of the absorption band at around 880 nm is 29 nm, indicating that the Nd:Gd0.1Y0.9AlO3 crystal can be pumped efficiently by laser diodes. Furthermore, the large full width at half maximum at 1083 nm and long fluorescence lifetime (189.53 μs) were obtained, which means that the Nd:Gd0.1Y0.9AlO3 crystal may be an attractive host for ultrashort pulse and tunable broadband lasers. Being pumped by an 880 nm laser diode, the laser operation of Nd:Gd0.1Y0.9AlO3 crystal at 1.0 μm was obtained for the first time. A maximum output power of 677 mW was obtained with the 10% output coupler, corresponding to an optical-to-optical conversion efficiency of 22.16% and a slope efficiency of 27.80%. All these results show that Nd:Gd0.1Y0.9AlO3 crystal is a new mixed laser host which is suitable for 880 nm laser diode pump.

Spectral properties and highly efficient continuous-wave laser operation in Nd, Gd:CaF2 crystals

Spectral properties of Nd, Gd:CaF2 crystals were investigated. In comparison with Nd:CaF2, the spectral parameters of Nd, Gd:CaF2 were altered in a large scale. LD-pumped true CW laser has been demonstrated in the crystals. The slope efficiency with the value of 45% in 0.5 at.% Nd, 5 at.% Gd:CaF2 was achieved, it is the highest slope efficiency in Nd doped CaF2 single crystals by LD-pumping. The system is a promising candidate for highly efficient lasers.

Growth, spectral properties, and diode-pumped laser operation of a Nd3+-doped LaMgAl11O19 crystal.

A Nd3+-doped LaMgAl11O19 (Nd:LMA) crystal was grown by the Czochralski method. Room temperature polarized absorption spectra, fluorescence spectra, and fluorescence lifetime of the Nd:LMA crystal were measured and analyzed. The Judd-Ofelt parameters Ω2,4,6 were calculated to be 1.21×10-20, 3.63×10-20, and 2.35×10-20 cm2, respectively. The absorption and emission cross sections were calculated. Using a 790-nm diode laser as pump source, continuous-wave laser operation of an a-cut Nd:LMA crystal has been demonstrated with a maximum output power of 1.71W and slope efficiency of 40.4% for a 1055nm laser. Low-gain laser operation at 1082nm is also realized with a maximum output power of 1.46W and slope efficiency of 34.5%.

Tunable and passively Q-switched laser operation of Nd,Lu:CaF2 disordered crystal.

We report the first demonstration, to the best of our knowledge, of tunable and Q-switched lasers based on diode-pumped Nd,Lu:CaF2 disordered crystal. A continuous tuning range of approximately 32nm (1047-1079nm) was obtained for tunable operations. A passively Q-switched laser was successfully achieved using a Cr4+:YAG as a saturable absorber. The shortest pulse width of 275ns was obtained with a repetition rate of 1.85kHz and corresponding peak power and single pulse energy of 189W and 51.9μJ, respectively.

926 nm laser operation in Nd:GdNbO4 crystal based on 4F3/2 → 4I9/2 transition

926 nm laser operation in a Nd:GdNbO4 crystal based on quasi-three-level 4F3/2 → 4I9/2 transition is reported, for the first time to our best knowledge. An average output power of 393 mW at 926 nm under 879 nm LD pumping is obtained with a slope efficiency of 33.3% and an optical-to-optical efficiency of 26.0%. The slope efficiency with respect to absorbed pump power is estimated to be 47.7%. Comparison between output characters of 926 nm laser under direct and indirect pumping is conducted. The average output power at 926 nm under 808 nm LD pumping reaches 305 mW with an optical-to-optical efficiency of 16.1%.

Thermal, spectral properties and Q-switched laser operation of Nd:SrLaAlO4 crystal

The thermal and spectral properties of a Nd:SrLaAlO4 (Nd:SLA) crystal were systematically studied, including thermal diffusivity, thermal expansion, specific heat, thermal conductivity, polarized absorption and emission spectra. Both continuous-wave (CW) and passively Q-switched Nd:SLA laser operations were investigated. The maximum CW output power of 3.54 W was obtained at 1.077 μm, corresponding to an optical-to-optical efficiency of 46.4%. In the passively Q-switched regime, the maximum average power, pulse repetition rate, and shortest pulse width were 1.8 W, 113 kHz, and 12.6 ns, respectively. All the results indicate that the Nd:SLA crystal is a highly efficient gain medium for laser applications.

Nd:LYAG and Nd:LGAG Mixed Crystals: Potential Candidates for 1.83 μm Laser Source

We report here, for the first time, diode-pumped continuous-wave laser operation of Nd:LuYAG (LYAG) and Nd:LuGdAG (LGAG) mixed crystals around 1.83 μ m. Cooling the laser samples down to about 6 °C, output powers of about 0.56 and 0.46 W with slope efficiencies of about 5.5% and 5.6% can be achieved, respectively, for the two crystals. These ${\rm{Nd}}^{3+ }{- \rm{doped}}$ garnet mixed crystals, like single crystal Nd:YAG, are believed to be the potential for laser generation at the important 1.83- μ m near-infrared wavelength domain.

Crystal growth, spectral properties, and continuous wave laser operation of Nd:GdNbO4

Nd:GdNbO4 crystal was grown successfully by the Czochralski (CZ) method. The continuous wave (CW) laser operation of Nd:GdNbO4 crystal at 1066 nm was reported for the first time. A maximum output power of 1.076 W with the incident power of 3.28 W was successfully obtained, corresponding to an optical-to-optical conversion efficiency of 32.8% and a slope efficiency of 35.3%. The absorption and fluorescence spectra of the crystal were measured at room temperature. By using the Judd-Ofelt approach, the intensity parameters were calculated to be 6.13 × 10−20, 1.56 × 10−20, and 2.81 × 10−20 cm2, respectively. The large absorption cross section (9.5 × 10−20 cm2) and broad absorption band (5 nm) at around 808 nm indicates that Nd:GdNbO4 crystal can be pumped efficiently by laser diodes (LD). The small emission cross section (9.3 × 10−20 cm2) and relatively long fluorescence lifetime (178 μs) of Nd3+ demonstrate good energy capacity of Nd:GdNbO4. All the results show that Nd:GdNbO4 crystal is a promising novel laser crystal suitable for LD pumping.

Structure, spectroscopic properties and laser performance of Nd:YNbO4 at 1066 nm

We have demonstrated continuous wave (CW) laser operation of Nd:YNbO4 crystal at 1066 nm for the first time. A maximum output power of 1.12 W with the incident power of 5.0 W is successfully achieved corresponding to an optical-to-optical conversion efficiency of 22.4% and a slope efficiency of 24.0%. The large absorption cross section (8.7 × 10−20 cm2) and wide absorption band (6 nm) at around 808 nm indicates the good pumping efficiency by laser diodes (LD). The small emission cross section (29 × 10−20 cm2) and relative long lifetime of the 4F3/2 → 4I11/2 transition indicates good energy storage capacity of Nd:YNbO4. Moreover, the raw materials of Nd:YNbO4 are stable, thus, it can grow high-quality and large-size by Czochralski (CZ) method. Therefore the Nd:YNbO4 crystal is a potentially new laser material suitable for LD pumping.

Efficient laser operation based on transparent Nd:Lu2O3 ceramic fabricated by Spark Plasma Sintering.

Efficient laser operation of Nd:Lu2O3 ceramic fabricated by Spark Plasma Sintering (SPS) was demonstrated. Transparent Nd:Lu2O3 ceramic was successfully fabricated by Spark Plasma Sintering and its laser experiment was done. On the 4F3/2 to 4I11/2 transition, the obtained maximum output is 1.25W at the absorbed pump power of 4.15W with a slope efficiency of 38% and two spectral lines at 1076.7nm and 1080.8nm oscillated simultaneously. The slope efficiency of 38% is near two times higher than the previously demonstrated SPSed Nd:Lu2O3 ceramic lasers. On the 4F3/2 to 4I13/2 transition, the laser operated at the wavelength of 1359.7nm and the maximum output of 200mW was obtained at the absorbed pump power of 2.7W.

Diode-pumped Nd:LuAG ceramic laser on 4F3/2-4I13/2transition

Laser operation of Nd:LuAG ceramic on the 4F3/2-4I13/2 transition has been demonstrated for the first time, to the best of our knowledge. Different output couplers are used to optimize the laser performance and the highest slope efficiency of 18.0% as well as maximum output power of 3.05 W under the pump power of 21 W was obtained. The spectral characteristics of Nd:LuAG ceramic laser is carefully studied and compared with Nd:YAG ceramic laser's. In our experiment, it has been observed that the 1338 nm wavelength is always the initial and strongest oscillating spectral line when Nd:LuAG ceramic laser operates on the 4F3/2-4I13/2 transition, even though the pump level or intra-cavity loss changes greatly, which is quite different from the case of Nd:YAG ceramic laser.

Spectroscopic, thermal and cw dual-wavelength laser characteristics of Nd:LaF3 single crystal

A Nd-doped LaF3 crystal was grown by Czochralski method, and the rocking curves of (002) and (110) diffraction planes show good crystallinity quality of the as-grown crystal. Room-temperature fluorescence spectrum and transmittance spectrum of Nd:LaF3 crystal were investigated, both indicating probable dual-wavelength emissions at ∼1.04μm and ∼1.06μm. The thermal diffusivity and thermal conductivity of Nd:LaF3 crystal were detailed studied. Cw dual-wavelength laser operation of Nd:LaF3 single crystal at 1040nm and around 1065nm with LD pumping was demonstrated. A maximum output power of 302mW was obtained with a slope efficiency of about 18.5% with respect to the pump power. The results of our study indicate the Nd:LaF3 crystal a promising laser crystal.

Nd:(Gd0.3Y0.7)2SiO5 crystal: A novel efficient dual-wavelength continuous-wave medium

Efficient dual-wavelength continuous-wave (CW) and passively Q-switched laser operation of Nd:(Gd0.3Y0.7)2SiO5 crystal were investigated for the first time to our knowledge. Maximum CW output power of 2.3W was obtained under the absorbed pump power of 4.6W, corresponding to the slope efficiency of 55%. Dual-wavelength CW laser with respective wavelengths around 1074nm and 1078nm were achieved. With Cr4+:YAG as the saturable absorber, passive Q-switched performance was obtained. The slope efficiency of passively Q-switched operation was 45%. The shortest pulse width, the corresponding pulse energy and peak power were calculated to be 13.1ns, 50.2μJ and 3.8kW, respectively.

Femtosecond mode-locked Nd(3+)-doped Ba(Zr,Mg,Ta)O(3) ceramic laser.

We have demonstrated continuous wave (CW) laser operation and the first, to the best of our knowledge, sub-200 fs mode-locked laser operation of Nd(3+)-doped Ba(Zr,Mg,Ta)O(3) ceramic. Its disordered crystalline nature exhibits a broad gain bandwidth of 30 nm with a high-emission cross section. It also has higher thermal and mechanical properties than Nd:glass. In CW operation, a maximum output power of 1.5 W under 6.2 W of absorbed pump power was obtained. In mode-locked operation, a pulse duration of 196 fs with an average power of 60 mW was successfully achieved. The laser spectrum straddled both fluorescence peaks of A-site and B-site Nd(3+) ions.