Doped Laser Research Articles

Two dimensional ferroelectric domain patterns in Yb3+ optically active LiNbO3 fabricated by direct electron beam writing

We report on highly controllable ferroelectric domain inversion in Yb3+ doped LiNbO3 laser crystal. The ferroelectric domain patterns are fabricated by direct electron beam writing without any previous masking process. Square lattices of inverted domains with diameters and distance between domains as low as 1 μm are demonstrated. The lateral growth of the inverted domains is analyzed as a function of the applied charge and the threshold values for domains in the 1–10 μm length scale are determined. Spatially resolved low temperature fluorescence spectroscopy and non-collinear second harmonic generation experiments are also employed to evaluate the optical properties of the system.

Sub-100 fs pulse generation in a diode pumped Yb:Sc2SiO5 laser

We report on the sub-100fs pulse generation in a diode pumped Yb3+:Sc2SiO5 (Yb:SSO) laser. Pumped by a 976nm single emitter diode and mode-locked with a SESAM, the laser generated stable mode locked pulses with 71fs duration, 89MHz repetition rate, and an average power of 38mW at 1044.6nm under the incident pump power of 6.5W. To the best of our knowledge, this is the shortest pulse ever produced from an Yb3+ doped orthosilicate crystal laser.

Diode-pumped continuous-wave quasi-three-level Nd:GYSGG laser at 937 nm

A continuous-wave (cw) 937nm Nd:GYSGG laser based on the quasi-three-level transition 4F3/2 to 4I9/2 is reported. The output power of 0.80W at 937nm is achieved with the pump power of 8.2W, corresponding to the conversion efficiency of 9.8%. The variation of output power and pump threshold with increased working temperature is also studied, which demonstrates the deterioration operation because of the serious reabsorption in a quasi-three-level Nd3+ doped laser.

Versatile large-mode-area femtosecond laser-written Tm:ZBLAN glass chip lasers

We report performance characteristics of a thulium doped ZBLAN waveguide laser that supports the largest fundamental modes reported in a rare-earth doped planar waveguide laser (to the best of our knowledge). The high mode quality of waveguides up to 45 um diameter (~1075 μm(2) mode-field area) is validated by a measured beam quality of M(2)~1.1 ± 0.1. Benefits of these large mode-areas are demonstrated by achieving 1.9 kW peak-power output Q-switched pulses. The 1.89 μm free-running cw laser produces 205 mW and achieves a 67% internal slope efficiency corresponding to a quantum efficiency of 161%. The 9 mm long planar chip developed for concept demonstration is rapidly fabricated by single-step optical processing, contains 15 depressed-cladding waveguides, and can operate in semi-monolithic or external cavity laser configurations.

Tuning the wavelength of amplified spontaneous emission coupled to localized surface plasmon

Amplified spontaneous emissions (ASEs) with a tuned wavelength have been observed in a thin film composite made by spin-coating a dye-doped polymer layer (thickness ∼80 nm) on Ag nanoparticles deposited on a SiO2 substrate. The samples having a varied wavelength of the localized surface plasmon resonance (LSPR) are excited with second harmonic pulses from a Nd3+ doped yttrium aluminum garnet laser. When the pump energy exceeds a threshold, a spectrally narrow peak appears on a broad emission from dye molecules with a nonlinear increase in emission intensity, indicating an onset of ASE. It is found that the peak wavelength of ASE shifts with the change of the wavelength of LSPR.

Pr^3+ cluster management in CaF_2 by codoping with Lu^3+ or Yb^3+ for visible lasers and quantum down-converters

The codoping of CaF2:Pr3+ with Yb3+ or Lu3+ ions is shown to avoid the clustering of Pr3+ ions, which otherwise prevent Pr3+ doped CaF2 to be used for various photonic applications. The breaking of Pr3+ clusters by Lu3+ ions paves the way towards the development of a Pr3+ doped CaF2 visible laser. On the other hand, the formation of Pr3+-Yb3+ clusters in place of Pr3+ clusters leads to extremely efficient energy transfers between Pr3+ and Yb3+ which could be used for quantum cutting applications. Two types of clusters are observed for both types of codopings. Pr3+ to Yb3+ energy transfer analysis shows that for one of the clusters an ultrafast energy transfer takes place with a rate of 5×107  s−1, which is likely due to exchange interaction.

Structural characteristics and optical properties of plasma assisted reactive magnetron sputtered dielectric thin films for planar waveguiding applications

Thin films of aluminum oxide (Al2O3), tantalum pentoxide (Ta2O5), titanium oxide (TiO2), yttrium oxide (Y2O3) and zirconium oxide (ZrO2) were deposited by plasma assisted reactive dual magnetron sputtering to determine their suitability as a host for a rare earth doped planar waveguide upconversion laser. The effect of deposition parameters such as cathode, plasma power and oxygen gas flows were studied and the operational working points were determined. Both power and lambda control were used to optimize the optical quality of each material. By using lambda control feedback system, the magnetron power fluctuates to sustain a fixed oxygen flow in the target area reducing the compound layer growth on the material and maintaining a healthy deposition rate. The optical properties, structure and crystalline phase of each film were found to be dependent on the process parameters. X-ray diffraction (XRD) analysis revealed that the thin films varied from amorphous to highly crystalline depending on the deposition conditions. X-ray photoelectron spectroscopy (XPS) was utilized for surface compositional analysis revealing that films had varying stoichiometric ratios which are controlled for each material by the deposition parameters chosen. The waveguide loss for the thin film layers was investigated and Ta2O5 was shown to have a slab waveguide loss of ~1dB/cm at both visible and infra-red wavelengths making it ideal for planar waveguide and laser applications. TiO2, Y2O3 and ZrO2 were found to deposit in a highly crystalline phase. Waveguiding in the TiO2 layers was not possible at 633nm or in the infrared region. The Y2O3 samples gave low loss (2–4dB/cm) at the 1.3 and 1.5μm wavelengths but no waveguiding at 633nm or 833nm was possible. Atomic force microscopy showed rough surface topography for TiO2, Y2O3 and ZrO2 akin to their crystalline growth with the SEM images confirming the regular crystalline columnar structure for the case of Y2O3 and ZrO2.

Ceramic laser materials: Past and present

Recently, 100KW output power from YAG ceramic laser system has been demonstrated. It is a remarkable achievement considering that only a few milli-watt power was observed from the ceramic laser materials when first reported in the 1960s. This great improvement is mainly due to the success in high purity powder synthesis, development in new sintering technology and novel ideas in optics and device design. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2–3μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. In this paper, we highlight some of these notable milestones and achievements and forecast the future in polycrystalline ceramic laser materials.

21 μm waveguide laser fabricated by femtosecond laser direct-writing in Ho^3+, Tm^3+:ZBLAN glass

We report the first Ho3+ doped waveguide laser, which was realized by femtosecond direct-writing of a depressed cladding structure into ZBLAN glass. Tm3+ sensitizing allows the 9 mm long Ho3+ gain medium to be conveniently pumped at 790 nm, achieving an optical-to-optical slope efficiency of 20% and a threshold of 20 mW. The potentially widely tunable laser produces up to 76 mW at 2052 nm and also operates at shorter wavelengths near 1880 nm and 1978 nm for certain cavity configurations.

Ceramic Laser Materials.

Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG) ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements.

Simulation of the passively mode-locked laser with a SESAM

By solving the Haus master equation through split step Fourier transform method, several programs which can simulate the soliton mode-locked dynamic processes of the passively mode-locked solid laser with a semiconductor saturable absorber mirror (SESAM) are established, based on a MATLAB environment. The pulse evolution equations are solved numerically. Sample calculations for a diode-pumped Nd3+:YVO4 (0.5% doped) laser with a SESAM are presented to demonstrate the use of the simulation programs and the related formulas. Several theoretical results such as the pulse width, the peak power and the average output power are obtained with a given cavity structure, which are in good agreement with the reported experimental results.

Yb3+ doped fluorophosphate laser glasses with high gain coefficient and improved laser property

Yb3+ doped fluorophosphate glasses with high stimulated emission cross-section, large gain coefficient and low hydroxyl absorption coefficient were prepared by high temperature melting for fiber laser applications, and their spectral, general laser parameters were investigated accordingly by means of fluorescence emission spectrum, decay cure and infrared absorption spectra. Compared with previously reported fluorophosphate glasses, the investigated fluorophosphate glasses have highest grain coefficient and maintain a maximum laser systematical factor over other various types of laser glasses. The introduction of fluorides to fluorophosphate glasses results in the low level of hydroxyl absorption coefficient and concentration. All these advantages might mean that Yb3+ doped fluorophosphate glasses are a good candidate as an active laser media for short pulse, high power laser generation used for next generation nuclear fusion.

Efficient continuous wave deep ultraviolet Pr3+:LiYF4 laser at 261.3 nm

We report continuous wave deep ultraviolet laser operation at 261.3 nm by intracavity frequency doubling of laser diode pumped Pr3+ doped LiYF4 lasers. Using two InGaN laser diodes with a maximum output power of about 1 W each, a 2.9 mm long Pr3+:LiYF4 crystal and a 5 mm long beta-barium-borate crystal, coherent radiation with an output power of 481 mW at 261.3 nm was achieved at an optical-to-optical efficiency of 26.1% with respect to the total pump power. Both, linear and nonlinear losses have been calculated to be approximately 0.6% by using a model for intracavity frequency doubling with focussed Gaussian beams.

Progress in mid-IR Cr^2+ and Fe^2+ doped II-VI materials and lasers [Invited

Recent progress in fabrication and mid-IR lasing of transition metal doped II-VI single crystal and thermo-diffusion doped polycrystalline and hot-pressed ceramic gain media as well as nano and micro-crystalline laser active powders, powders in the liquid suspension, polymer-film, thin film waveguides and chalcogenides glass composites is reported.

High power diode-pumped 27-μm Er^3+:Y_2O_3 laser with nearly quantum defect-limited efficiency

We report diode-pumped Er3+:Y2O3 ceramic laser with ~14 W of true CW output at ~2.7 μm. This presents nearly ten-fold power increase with respect to previous best result with this laser material. We also believe this to be the highest power ever reported from Er3+ -doped bulk crystalline laser operating in a ~3-μm wavelength range. Power-scaled performance of 974-nm pumped Er3+:Y2O3 laser was achieved with the slope efficiency of ~26%.

Particle swarm optimization-based approach for accurate evaluation of upconversion parameters in Er^3+-doped fibers

In this Letter, a method for recovering homogeneous upconversion coefficients (HUCs) in Er(3+)-doped glasses and erbium-activated devices is illustrated. It is based on a particle swarm optimization (PSO) approach. The HUCs are calculated on the basis of known values of optical gain evaluated in different pumping conditions. The obtained numerical results proof that the proposed technique provides solutions that are very close to the expected values. Therefore the method constitutes a tool for the design and optimization of efficient rare-earth doped lasers and optical amplifiers. This approach can be considered a feasible and valid alternative method in the field of material science and optical engineering for determining HUCs and avoiding the employment of expensive equipment for the measurement of ion-ion interaction parameters.

石墨烯锁模掺铒光纤脉冲激光器的实验研究

石墨烯锁模掺铒光纤脉冲激光器的实验研究

石墨烯锁模掺铒光纤脉冲激光器的实验研究

石墨烯锁模掺铒光纤脉冲激光器的实验研究

石墨烯锁模掺铒光纤脉冲激光器的实验研究

石墨烯锁模掺铒光纤脉冲激光器的实验研究

全光纤掺镱激光器实现锁模和多波长输出

全光纤掺镱激光器实现锁模和多波长输出