Compact high-power mode-locked Nd：YVO4 picosecond laser using multiple-pass cavity

A stable self-starting mode-locked Nd:YVO4 laser with a Herriott-type multiple-pass cavity(MPC) operating at 1 064 nm is demonstrated.An in-band 880-nm laser diode is used as an end-pump and a semiconductor saturable absorber mirror(SESAM) is used for passive mode locking(ML) and providing pulse durations of 14 ps.At a pump power of 26.4 W,the maximum average output power is as high as 10.5 W at a repetition rate of 22 MHz,which corresponds to a single pulse energy of 0.48 μJ.Optical-tooptical conversion efficiency is as high as 39.8% at the maximum output power with a slope efficiency of 55.2%.     

A Bragg-Mirror-Based Semiconductor Saturable Absorption Mirror at 800 nm with Low Temperature and Surface State Hybrid Absorber

We present a novel 800-nm Bragg-mirror-based semiconductor saturable absorption mirror with low temperature and surface state hybrid absorber, with which we can realize the passive soliton mode locking of a Ti:sapphire laser pumped by 532-nm green laser which produces pulses as short as 37 fs. The reflection bandwidth of the mirror is 3Ohm and the pulse frequency is 107MHz. The average output power is 1.1 W at the pump power of 7.6W.     

Passively Mode-Locked Quasi-Three-Level Nd:LuVO4Laser with Semiconductor Saturable Absorber Mirror

We demonstrate a passively a Z-folded resonator. Using device, we achieve stable cw average output power under cw mode-locked Nd：LuVO4 laser operating on the quasi-three-level at 916nm with a semiconductor saturable absorber mirror （SESAM） as the passive mode-locking mode locking with 6.7ps pulse duration at repetition rate of 133 MHz and 88mW the pump power of 17.1 W.     

High-Power Nd：GdVO4 Innoslab Continuous-Wave Laser under Direct 880 nm Pumping

A high-power cw end-pumped laser device is demonstrated with a slab crystal of Nd：GdVO4 operating at 1063nm. Diode laser stacks at 880nm are used to pump Nd：GdVO4 into emitting level 4^F3/2. The 149 W output power is presented when the absorbed pump power is 390 W and the optical-to-optieal conversion efficiency is 38.2%. When the output power is 120 W, the M^2 factors are 2.3 in both directions. Additionally, mode overlap inside the resonator is analyzed to explain the beam quality deterioration.     

Generation of a Sub-10fs Laser Pulse by a Ring Oscillator with a High Repetition Rate

A compact femtosecond Ti：sapphire ring oscillator composed of chirped mirrors is designed. By accurately optimizing the intra-cavity dispersion and the mode locking range of the ring configuration, we generate laser pulses as short as 7.7fs with a repetition rate as high as 745 MHz. The spectrum spans from 660nm to 94Ohm and the average output power is 480mW under the cw pump laser of 7.5 W.     

5.1-ps passively mode-locked Nd:Gd_(0.42)Y_(0.58)VO_4 laser with a LT-GaAs absorber

We propose a diode end-pumped passively mode-locked Nd:Gd_(0.42)Y_(0.55)VO_4 (Nd:GdYVO_4) laser at 1064 nm using a GaAs absorber grown at low temperature as the output coupler.Stable continuous-wave (CW) mode locking with a 5.1-ps pulse duration at a repetition rate of 113 MHz is obtained.The maximum average output power is 2.29 W at the incident pump power of 12 W with the slope efficiency of about 24.8%.     

A Stable 2012.1 nm Single-Longitudinal-Mode Tm：YAG Ceramic Laser with Volume Bragg Grating and Fabry-Perot Etalon

We demonstrate a stable single longitudinal mode Tm：YAG ceramic laser operating at a single wavelength of 2012.1 nm. The single-longitudinal-mode Tin： YAO ceramic laser is obtained by employing volume Bragg grating as one cavity mirror and inserting a Fabry-Perot etalon into the laser cavity. A maximum single longitudinal mode output power of 165roW with a slope efficieney of 6.6% is achieved under the pump power of 5.02 W. The laser has a beam quality of M2 = 1.18 at the maximum single longitudinal mode output power.     

Laser Characteristics of Cladding-Pumped Short Er^3＋/yb^3＋ Codoped Single Mode Phosphate Glass Fibre

We experimentally investigate the laser characteristics of a series of short pieces of newly-developed Er^3＋/ Yb^3＋ codoped single mode phosphate glass fibres via the cladding pump of a 976nm multimode laser diode. A stable continuous-wave single transverse mode laser with over 85 m W at 1553nm is generated from a 5.5-em-long active fibre. Single mode laser output power per unit length is up to 15 mW/cm. Moreover, the slope efficiency is 11.8% when the pump power is below 940mW and the 3dB linewidth is 0.06nm at the maximum pump power. The numerical simulation results show that the laser emission slope efficiency can exceed 20% by means of increasing the coupling efficiency of the pump to the fibre core further.     

A Diode-Pumped 1617 nm Single Longitudinal Mode Er：YAG Laser with Intra-Cavity Etalons

We demonstrate the continuous wave p-polarized single longitudinal mode （SLM） operation of an Er：YAG laser at 1617.6nm pumped by a diode-laser with three inserted Fabry-Perot （FP） etalons at room temperature. The Brewster angle inserted FP is applied to obtain the p-polarized laser. For free running, the maximum output power is 570 m W with a pump power of 12.5 W. An incident pump power of 12.5 W is used to generate the maximum p-polarized single longitudinal mode output power of 78.5 m W, corresponding to a slope efficiency of 1.6% and an optical-to-optical efficiency of 0.61%. The beam quality M2 is measured to be 1.15 at the highest SLM output power. This stable polarized SLM oscillation is encouraging due to its application for an injection-locked system used as a master laser.     

High power CW and diode-side-pumped Q-switched operation of a Nd：YAG 1319-nm laser

We demonstrated the highly efficient continuous wave （CW） and Q-switched infrared laser from a diode- side-pumped Nd：YAG crystal. A CW output as high as 66 W at 1319 nm was achieved under the pump power of 460 W, corresponding to a coversion efficiency of 14.3%. A maximum average power of 8.9 W of TEM00 mode was obtained in Q-switched operation at the repetition rate of 8 kHz. The performance of the laser considering the thermal lens effect induced by pump power was also analyzed.     

Nonlinear Polarization Rotation-Based Mode-Locked Erbium-Doped Fiber Laser with Three Switchable Operation States

A simple mode-locked erbium-doped fiber laser （EDFL） with three switchable operation states is proposed and demonstrated based on nonlinear polarization rotation. The EDFL generates a stable square pulse at a third harmonic pulse repetition rate of 87kHz as the 1480 nm pump power increases from the threshold of 17.5 m W to 34.3mW. The square pulse duration increases from 105 ns to 245ns as the pump power increases within this region. The pulse operation switches to the second operation state as the pump power is varied from 48.2mW to l16.Tm W. The laser operates at a fundamental repetition rate of 29 kHz with a fixed pulse width of 8.5 μs within the pump power region. At a pump power of ll6.TmW, the average output power is 3.84mW, which corresponds to the pulse energy of 131.5 ng. When the pump power continues to increase, the pulse train experiences unstable oscillation before it reaches the third stable operation state within a pump power region of 138.9 m W to 145.0 m W. Within this region, the EDFL produces a fixed pulse width of 2.8 μs and a harmonic pulse repetition rate of 58 kHz.     

2277-W continuous-wave diode-pumped heat capacity laser

A high power continuous-wave (CW) diode-pumped Nd:YAG laser operated in heat capacity mode is demonstrated by use of two identical highly efficient diode-pumped laser heads placed in a plane-plane resonator.The laser heads are uniformly pumped with a five-fold symmetrical side-pumping configuration, and each head is able to output maximum output power of 2200 W at 808 nm.Under a total pump power of 4290 W,the output power of the laser at 1064 nm is up to 2277 W,corresponding to an optical-to-optical efficiency of 53.1%.     

High power CW and Q-switched operation of a diode-side-pumped Nd:YAG 1319-nm laser

We demonstrated the highly efficient continuous wave(CW)and Q-switched infrared laser from a diode- side-pumped Nd:YAG crystal.A CW output as high as 66 W at 1319 nm was achieved under the pump power of 460 W,corresponding to a coversion efficiency of 14.3%.A maximum average power of 8.9 W of TEM_(00) mode was obtained in Q-switched operation at the repetition rate of 8 kHz.The performance of the laser considering the thermal lens effect induced by pump power was also analyzed.     

High power doubly resonant all-intracavity deep blue laser at 447 nm based on sum-frequency-mixing technology

A high power continuous-wave deep blue laser at 447 nm is obtained by using a doubly cavity and a type H critical phase matching KTP crystal for intracavity sum-frequency-mixing. With the incident pump power of 240 W for the Nd：YAP crystal and 120 W for the other Nd：YAP crystal, the deep blue laser output of 5.7 W at 447 nm with near fundamental mode is obtained, and the beam quality M^2 value equals 2.53 in both horizontal and vertical directions at the maximum output power. The power stability is better than 2% at the maximum output power during half an hour. The experimental results show that the intracavity sum-frequency mixing by doubly resonant is an effective method for high power blue laser.     

Diode-pumped 1123-nm Nd:YAG laser

We demonstrated a diode-pumped Nd:YAG laser with a plano-concave resonator. When the pump power is 1.57 W, the output power of 1123-nm laser is 132 mW at the temperature of 20 ℃, and the power change is less than 2% in an hour. A periodically poled LiNbO3 (PPLN) was used as outer cavity frequency-doubling crystal and 561-nm laser was observed.     

Efficient continuous-wave eye-safe region signal output from intra-cavity singly resonant optical parametric oscillator

We report an efficient continuous-wave (CW) tunable intra-cavity singly resonant optical parametric oscillator based on the multi-period periodically poled lithium niobate and using a laser diode (LD) end-pumped CW 1064 nm Nd:YVO 4 laser as the pump source.A highly efficiency CW operation is realized through a careful cavity design for mode matching and thermal stability.The signal tuning range is 1401-1500 nm obtained by varying the domain period.The maximum output power of 2.2 W at 1500 nm is obtained with a 17.1 W 808 nm LD power and the corresponding conversion efficiency is 12.9%.     

Highly efficient Nd:YAG/LBO laser at 473 nm under direct 885-nm diode laser pumping

<正>In diode pumped Nd:YAG lasers,the quantum defect is the most important parameter determining the thermal load of the laser crystal,which can be dramatically reduced by pumping directly into the upper laser level.A compact folded three-mirror cavity with a length of 105 mm is optimized to obtain a highly efficient 473-nm laser.When the absorbed pump power(with 15.8-W incident pump power) at 885 nm into Nd:YAG is 10 W,a continuous-wave 473-nm blue laser as high as 2.34 W is achieved by LBO intra-cavity frequency doubled.The optical-to-optical conversion efficiency is 14.8%.To the best of our knowledge, this is the highest efficiency at 473 nm by an intra-cavity doubled frequency Nd:YAG laser.     

High-Power Continuous-Wave Diode-End-Pumped Intracavity Frequency Doubled Nd：YVO4 Laser at 671 nm with a Compact Three-Element Cavity

We report a high-power high-efficient continuous-wave （cw） diode-end-pumped Nd：YVO4 1342-nm laser with a short plane-parallel cavity and an efficient cw intracavity frequency-doubled red laser at 671 nm with a compact three-element cavity. At incident pump power of 20.6 W, a maximum output power of 7 W at 1342 nm is obtained with a slope effciency of 37.3%. By inserting a type-Ⅰ critical phase-matched LBO crystal as intracavity frequencydoubler, a cw red output as much as 2.85-W is achieved with an incident pump power of 16.9 W, inducing an optical-to-optical conversion efficiency of 16.9%. To the best of our knowledge, this is the highest output of diodepumped solid-state Nd：YVO4 red laser. During half an hour, the red output is very stable, and the instability of output power is less than 1%.     

Characteristics of Nd：GdVO4 Laser with Different Nd-Doping Concentrations

We report the properties of a compact diode-pumped continuous-wave Nd：GdV04 laser with a linear cavity and different Nd-doped laser crystals. In a 0.2at.% Nd-doped Nd：GdVO4 laser, 1.54 W output laser power is achieved at 912nm wavelength with a slope efficiency of 24.8% at an absorbed pump power of 9.4W. With 0.3at.% Nd-doping concentration, we can obtain the either single-wavelength emission at 1064nm or 912nm or the dual-wavelength emission at 1064nm and 912nm by controlling the incident pump power. From an incident pump power of 11.6 W, the 1064nm emission between ^4Fa/2 and ^4I11/2 is suppressed completely by the 912nm emission between ^4Fa/2 and ^4I9/2. We obtain 670 mW output of the 912nm single-wavelength laser emission with a slope efficiency of 5.5% by taking an incident pump power of 18.4 W. Using a Nd：GdV04 laser with 0.4at.% Nd-doping concentration, we obtain either the single-wavelength emission at 1064nm or the dual-wavelength emission at both 1064nm and 912nm by increasing the incident pump power. We observe a strong competition process in the dualavelength laser.     

Q-Switched Large-Mode-Area Yb-Doped Fibre Laser Using GaAs as Saturable Absorber

A passive Q-switched large-mode-area Yb-doped fibre laser is demonstrated using a GaAs wafer as the saturable absorber. A high Yb doping concentration double-clad fibre with a core diameter of 30μm and a numerical aperture of 0.07 is used to increase the laser gain volume, permitting greater energy storage and higher output power than conventional fibres. The maximum average output power is 7.2W at 1080nm wavelength, with the shortest pulse duration of 580ns and the highest peak power of 161W when the laser is pumped with a 25W diode laser operating at 976nm. The repetition rate increases with the pump power linearly and the highest repetition rate of 77kHz is obtained in the experiment.