High-quality, ultrafast fiber lasers have long been favored by both research and industry for many desirable properties. Here, we present an Yb-doped fiber laser system by utilizing a directly spliced photonic crystal fiber to amplify a seed source, and sub-100 fs ultrashort pulses are obtained with an average power of 6.55 W and at a repetition rate of 100.15 MHz. The M2 factors are measured to be about M_x^2=1.13 an M_y^2=1.12, respectively. The standard deviation of output power over a 2.5-hour period is determined to be 0.72 % and no significant wavelength drifts or intensity fluctuations are observed. These results demonstrate the promising potential of this compact fiber laser system for both research and industrial applications.
Passively mode-locked fiber laser based on two-dimensional material MnPSxSey saturable absorber is studyed. By changing the doping ratio of S and Se, three magnetic materials, MnPS2.9Se0.1, MnPS2.8Se0.2 and MnPS2.7Se0.3, are obtained. The three materials were fabricated into sandwich absorbers, and stable mode-locked pulse was obtained in ytterbium-doped fiber lasers. The total length of the fiber laser is 88 m, and the corresponding repetition rate is 2.27 MHz. The signal-to-noise ratio of the three materials is all above 60 dB, indicating the stability of the mode-locking pulse. The experimental results show that MnPSxSey has good nonlinear optical modulation characteristics and optical switching ability, which has potential application value.
We have demonstrated an end-pumped mode-locked femtosecond Yb:KGW laser which assisted by a semiconductor saturable absorber mirror (SESAM). By using a 2.5% output coupler, the oscillator generated average output power of 2.5 W which pulses duration was 192 fs at a repetition rate of 69.5 MHz, corresponding to a pulse energy of 36 nJ and peak power of 187 kW.
We experimentally demonstrate wavelength-tunable Self-Mode-Locking (SML) operation generated in an Optically Pumped Semiconductor Disk Laser (OP-SDL) with a straight cavity. The operation is achieved by insetting an etalon into the cavity, and wavelength tuning range of 11 nm can be achieved by adjusting the angle of etalon. After aligning the cavity carefully, stable self-mode-locking is obtained when the pump power was beyond 5 W, and the pulse period of 0.99 ns agrees well with the round-trip time determined by the optical cavity length of 148 mm. Meanwhile, the RF spectrum reveals a clean peak at the fundamental repetition rate of 1.01 GHz and the signal-to-noise ratio of the RF spectrum reaches 60 dB during the whole tuning process, indicating the stability of the pulse was quite excellent. Finally, we obtained a wavelength tunable SML optically pumped semiconductor disk laser. The experimental results prove that under the condition of adding an etalon in the cavity, the OP-SDL could remain a stable operation in a wider wavelength tuning range. This research is helpful to the development of wavelength tunable self-mode-locking optically pumped semiconductor disk lasers and hopes to obtain practical applications in related fields.
Ultrashort pulse lasers are widely used in laser spectroscopy, microwave measurements, high-speed sampling, medical diagnostics, communication systems, and many other fields. This work presents a tunable self-mode-locked semiconductor disk laser, which is based on the combination of the Kerr effect in the gain chip and the soft aperture formed by the overlap of pumping and laser spot. A linear resonator with a length of 93 mm is formed by the high reflectivity distributed Bragg reflector at the bottom of the gain chip and the external output coupler with 100 mm curvature radium. The mode-locking can be started by fine-tuning the size of the pump spot and the length of the resonator, and a stable self-mode-locked output can be achieved at 980 nm wavelength. Then, a thickness of 2 mm birefringent filter is inserted into the resonator at Brewster angle, and a continuous tuning of 37 nm wavelength was obtained by rotating the filter. The repetition rate of achieved stable mode-locked pulse train at 980 nm is 1.6 GHz, the pulse width is 4.3 ps, the maximum output power is 467 mW, and the corresponding peak power is 68 W.
The synchronization of ultrashort pulses is an important research content in laser technology and has important applications in the fields of pump probe, optical frequency metrology, optical coherent synthesis, and nonlinear optics, etc. In this paper, the mode locking of two Yb-doped fiber lasers is realized by nonlinear polarization rotation, and then two circulators are used to make both two laser beams propagate in a piece of fiber. By matching the cavity length of one laser to the other, and with the cross phase modulation of two laser beams in the shared single-mode fiber, two lasers are passively synchronized. Two lasers deliver picosecond pulses near 1.04 μm and 1.05 μm, respectively, and the repetition rate is locked around 38.1100 MHz.
Taking advantage of the technology of dispersive Fourier transform (DFT), we experimentally observed the evolutionary dynamics of convention solitons(CSs) in a simplified Erbium-doped fiber laser. The periodic beating behavior that occurs during the build-up and disappearance of conventional solitons was discovered in a nonlinear polarization rotation (NPR) fiber lasers. We suggest the reasonable assumption that the periodic beating during the dynamic evolution may be a close connection with the modulation depth of the intracavity saturable absorber The results of this study can deepen researchers' understanding of the evolution of CSs and provide additional judgment dimensions for optimizing the laser parameters.
We demonstrated a wavelength tunable mode-locked optically pumped semiconductor disk laser (OP-SDL) based on a SESAM. The wavelength tuning is achieved by incorporating an uncoated, 100 μm thick, fused silica etalon into the cavity of the laser, and the central wavelength of the pulse train varied from 972 nm to 977 nm. The average power of the mode-locked states measured at different wavelengths was about 80mW, meanwhile, the repetition rate was 1.2 GHz in the tuning process, and the signal-to-noise ratio of the radio frequency spectrum signal exceeds 50 dB, which illustrates that the laser can maintain a stable mode-locked state even the central wavelength varies greatly. In addition, we calculated the influence of etalon's related parameters on its transmittance. This research contributes to the development of wavelength-tunable mode-locked OP-SDLs and to gain practical applications in related fields.
Generation of noise-like pulses in a nonlinear Yb-doped fiber amplification system is investigated in three pump configurations: forward pump, backward pump, and bidirectional pump, respectively. Noise like pulse with a pedestal width as short as 2.99 ps is obtained. The average powers, pulse spectra and auto-correlation traces are measured. The characteristics of noise-like pulses generated in different pump powers and pump configurations are discussed.
Q-switched Yb-doped fiber lasers based on 2H-MoTe2 was demonstrated in this paper. The saturable absorber (SA) was a film mixed by 2H-MoTe2 and polyvinyl alcohol (PVA). The modulation depth of the SA was 21.4% and the saturable optical intensity was 10.3 GW/cm-2. When the 2H-MoTe2 film was inserted into the cavity, the Q-switched pulses were obtained. To the best of our knowledge, this is the first time to realize the generation of Q-switching in a Yb-doped fiber laser based on 2H-MoTe2-PVA film.
Dark soliton is a promising tool in communication systems for its ability to preserve its good shape. This paper demonstrates the generation of dark soliton in an Yb-doped fiber laser with a compact figure-9 resonator based on the principle of nonlinear amplifying loop mirror. In this laser, when the polarization controller is located in the gain fiber or single-mode fiber, the generation of dark soliton, bright soliton and bright-dark soliton pair, as well as the transformation between them, can be realized. This experiment provides the evidence on the generation of dark soliton at 1 μm, and the results show that the figure-9 fiber laser may obtain dark soliton, bright soliton or bright-dark soliton pair by simply adjusting the PC, which is helpful to obtain dark-soliton pulses in fiber lasers.
A stable Yb doped pulsed fiber nonlinear amplifier are demonstrated. A noise like pulse with the pulse width of 84 fs is generated after compressing by the grating pair. The peak power is 12 kW and the signal-to-noise ratio of RF spectrum is over 80 dB. This experiment is expected to be applied in nonlinear imaging and other fields.
The rectangular noise-like pulse (NLP) and dissipative soliton resonance (DSR) were generated in a thulium-doped fiber laser based on a nonlinear optical loop mirror (NOLM). The NLP and DSR pulses could be switched in the fiber laser by properly manipulating the intracavitary polarization controller (PC). The two different states are investigated by using the optical spectrum and radio frequency spectrum. The center wavelength of NLP is 1930.11 nm with the 3-dB bandwidth of 12.19 nm, and aforesaid parameters of DSR is 1944.04 nm, 10.36 nm, respectively. The radio frequency spectrum of the NLP pulse has two sub-peaks obviously, corresponding to the unstable long pulse train in the time domain. These findings may contribute to distinguish two rectangular pulses and lucubrate the dynamics of the rectangular pulses.
Passively mode-locked optically pumped vertical external cavity surface-emitting lasers (OP-VECSELs) have unique properties, such as excellent beam quality, high-average output power and high repetition rate. Many applications, including frequency comb and supercontinuum, require pulses in the femtosecond regime. A numerical model in the femtosecond regime is essential to understand the pulse formation mechanism. In this paper, we present a numerical model of passively mode-locked VECSELs in the femtosecond regime. We analyze the influence of gain parameters, such as small-signal gain, saturation energy, and the gain bandwidth on the pulse characteristics. The results of the simulation can provide a direction for designing the gain chip.
We demonstrated the noise-like pulse (NLP) generation in an erbium (Er) doped fiber laser at 1560 nm based on 2HMoTe2. The saturable absorber (SA) was a film mixed by 2H-MoTe2 and polyvinyl alcohol (PVA). The moudulation depth of the SA was 21.4% and the saturable optical intensity was 10.3 GW/cm2. When the 2H-MoTe2 film was inserted into the cavity, the stable NLPs with 3-dB spectral bandwidth of 2.44 nm and the repetition rate of 33.7 MHz were obtained. The autocorrelation (AC) trace of NLP has a 1.14 ps spike and a 71 ps pedestal. When the pump power was 600 mW, the maximum output power was 26.09 mW. To the best of our knowledge, this is the first time to realize the generation of NLP mode locking in an Er-doped fiber laser based on 2H-MoTe2-PVA film.
An all-normal-dispersion WS2 mode-locked Yb-doped fiber laser was demonstrated. The saturable absorber (SA) is a piece of WS2-PVA film which is sandwiched between two fiber connectors. The modulation depth and saturation intensity of the WS2-PVA film were 1.78% and 81 MW/cm2 , respectively. When the WS2-PVA film was utilized in the laser cavity, stable mode locking occurred with the pump power of 140 mW. The maximum single pulse energy was estimated to be more than 2.82 nJ. Besides, in order to know more about the influence of the SA on the generation of ultrashort pulses, the dynamic evolution of mode-locked lasers with the parameters of SAs was studied by solving the Ginzburg-Landau equation. Thus the high pulse energy could be reached.
The band structure of InGaAs strained quantum wells are investigated using 8×8 Luttinger-Kohn Hamiltonian including conduction band, heavy hole, light hole, spin-orbit splitting and strain effects. The energy dispersion curves of conduction band and valence band, the material gain spectra of TE and TM mode are given, respectively. The variation of peak gain with carrier density, temperature, well width, and Indium composition of InGaAs are calculated. The calculations show that the higher the In composition of InGaAs and the thicker the well, the longer the emitting wavelength are. The higher carrier density and higher In composition lead to the higher peak gain.
We demonstrated the noise-like pulse (NLP) generation in an ytterbium-doped fiber (YDF) laser with tungsten disulphide (WS2). Stable fundamental mode locking and second-order harmonic mode locking were observed. The saturable absorber (SA) was a WS2-polyvinyl alcohol film. The modulation depth of the WS2 film was 2.4%, and the saturable optical intensity was 155 MW cm−2. Based on this SA, the fundamental NLP with a pulse width of 20 ns and repetition rate of 7 MHz were observed. The autocorrelation trace of output pulses had a coherent spike, which came from NLP. The average pulse width of the spike was 550 fs on the top of a broad pedestal. The second-order harmonic NLP had a spectral bandwidth of 1.3 nm and pulse width of 10 ns. With the pump power of 400 mW, the maximum output power was 22.2 mW. To the best of our knowledge, this is the first time a noise-like mode locking in an YDF laser based on WS2-SA in an all normal dispersion regime was obtained.
The output characteristics of the mode-locked thulium-doped fiber laser with MoS2 as saturable absorber are simulated based on rate equation and nonlinear Schrodinger equation. With small signal gain efficient as variable, the effect of pump power, length of gain fiber, doping concentration and other parameters on output characteristics are analyzed. The theoretical results show an optimum doping concentration or fiber length exists to obtain maximum gain and average output power for given doped fiber. In experiment a thulium-doped fiber laser is setup and the experimental output characteristics of the laser are compared with theoretical counterpart, as a result, theoretical results are well in consistence with experimental results.
The high energy noise-like pulses (NLPs) were experimentally investigated in a passively mode-locked erbium-doped fiber laser with a long ring cavity by using nonlinear polarization rotation technique. Large net normal group-velocity dispersion of the cavity is estimated as high as 6.46 ps2, which is beneficial to formation of high-energy pulses. With the total pump power of 970 mW (the pump powers of forward pump and backward pump are set at the value of 455 mW and 515 mW, respectively), a stable ultrahigh energy rectangular-shape pulse emission with the pulse duration of 35 ns was observed. The energy of square packet with a fundamental repetition rate of 141.6 kHz is as high as 840 nJ. The signal-to-noise is higher than 60 dB in RF spectrum. The feature of NLPs is confirmed by the coherent spike of autocorrelation trace. When the pump power is beyond 970 mW, the mode locking operation with fundamental repetition rate cannot be achieved despite of the large range variation of polarization controller (PC) settings. However, the forthorder harmonic mode locking can be observed, the square pulse packet duration still remains at ∼ 35 ns. The experimental results demonstrated that the ultrahigh energy NLPs is only realized at the condition of special physical parameters and it is restricted by the number and intensity of ultra short pulses within the envelope to some extent.
KEYWORDS: Multilayers, Semiconductor lasers, Semiconductors, Disk lasers, Aluminum, Gallium, Gallium arsenide, Superlattices, Phonons, Chemical species
Thermal properties of multiple layers including distributed Bragg reflector (DBR) and multiple quantum wells (MQWs) used in the semiconductor gain element are crucial for the performance of a semiconductor disk laser (SDL). For the purpose of more reasonable semiconductor wafer design, so to improve the thermal management of SDLs, accurate thermal conductivity value of a DBR is under considerable requirement. By the use of equilibrium molecular dynamics (EMD) method, thermal conductivities of AlAs/GaAs DBRs, which were widely employed in 1μm wavelength SDLs, were calculated, and simulated results were compared with reported data. Influences of the Al composition, and the layer thickness on the thermal conductivities were focused and analyzed.
We experimentally demonstrated a Q-switched mode-locked (QML) and a continuous-wave mode-locked (CWML) ytterbium-doped fiber lasers with topological insulator: Bi2Se3 as saturable absorber (SA) in all normal dispersion regime. The Bi2Se3-SA is conventionally composited by embedding Bi2Se3 nanoplatelets into polyvinyl alcohol thin film, which provides a modulation depth of 7.6% and a saturation intensity of 38.9 MW/cm2. Based on this SA, with different cavity length, ytterbium-doped fiber laser can be operated at QML and CWML state, respectively. In the QML operation, a Q-switched envelope has the shortest pulse width of 1.12 μs and the tunable repetition rate from 96 to 175 kHz. The largest pulse envelope energy is 39.6 nJ, corresponding to average output power of 6.93 mW. In the CWML operation, an environmentally stable dissipative soliton laser pulse with pulse duration of ∼210 ps is obtained. The single pulse energy is 0.83 nJ with the repetition rate of 11.38 MHz at the wavelength of 1037 nm.
We demonstrate a mode locked fiber laser based on single wall carbon nanotubes. The mode locking is achieved by the evanescent field interaction of the propagating light with a single wall carbon nanotubes saturable absorber in a microfiber. The pulse width is 114fs. The maximum average output power is 21mW. The center of the wavelength is 1556nm with 26nm spectral width. The repetition rate is 111.6MHz. Keywords: Ultrafast lasers; Mode locked lasers; carbon nanotubes.
A model of 1.2μm Phosphorus doped Raman fiber laser is discussed. It is pumped by a 1.035μm high power
Yb-doped dual-cladding fiber laser. The coupled equations for forward and backward stokes waves are set up. An
approximate solution for the first –order Stocks laser is obtained by using ‘fsolve’ function in MATLAB which is simply
for writing and calculates fast. The relationships between energy conversion efficiency and the length of P-doped fiber,
the reflectivity of the output FLM are discussed respectively. And the laser system is optimized.
The single-walled carbon nanotubes (SWCNT) could be used as saturable absorber in Q-Switched and mode-locked lasers. In this paper, the influence of the concentration and the ultrasound time on the absorption coefficient of the single-walled carbon nanotubes was discussed. The structure and morphology of the single-walled carbon nanotubes were investigated by the atomic force microscope(AFM)and the scanning electron microscopy(SEM). When the single-walled carbon nanotube saturable absorbers (SWCNT-SAs) were used in both the Yb-doped double cladding fiber laser and the solid state lasers, the Q-switched pulses were obtained. And we use the single-walled carbon nanotubes saturable absorber (SWCNTs) in the passively Q-switched Nd:YCOB (Nd3+:(Nd3+:YCa4O(BO3)3) laser, a duration of 1.6μs pulses were obtained at the center wavelength of 1085.3 nm, a 175 mW output power were obtained at the pump power of 9W.
We demonstrate a Q-switched Ytterbium-doped double-cladding fiber laser based on single-walled carbon nanotubes as saturable absorbers. The pure single-walled carbon nanotubes were directly deposited on the one end of the Ytterbium-doped double-cladding fiber by optically driven deposition method. A linear-cavity was employed and a 1.5m long Ytterbium-doped double-cladding fiber played as the gain fiber. The Ytterbium-doped double-cladding fiber was pumped by a 976-nm fiber coupled diode laser. The maximum output power of 1.3W was obtained at the wavelength of 1070nm. The pulse-repetition rates were tuned from 9.1 KHz to 60 KHz when the pump powers were changed from 1.85W to 10W and the shortest pulse duration was around 600ns.
A passively Single-walled carbon nanotube is a new material as a saturable absorber to obtain a Q-switched laser or a mode-locked laser because of it’s broadband absorption wavelength and cheaper price comparing with SESAM. Here, by using a single-walled carbon nanotube as saturable absorber (SWCNT-SA), a passively Q-switched Nd:YCOB (Nd3+:YCa4O(BO3)3)laser was realized at 1085.3nm pumped by a 808 nm diode laser .The fluorescence spectrum of Nd:YCOB crystal near 1.06 μm. The output power of the Q-switched laser of 175 mW were obtained at the pump power of 9W in a V-type cavity. The range of the repetition rate was from 35 kHz to 62.5 kHz and pulse width was 1.6μs (FWHM) at 62.5 kHz.
In the nonlinear polarization rotation (NPR) mode locking fiber laser, the electric fields of different intensity of pluses
will have different nonlinear phase shifts because of self phase modulation (SPM) and cross-phase modulation (XPM)
effects. In this paper we analysis the SPM and XPM effect on the characteristics of pulses in fiber which were
influenced when we adjustment the wave plates in the NPR fiber lasers. At the same time, we discussed the pulses
waveform's influence caused by the strength of the SPM and XPM in fibers.
With 4th-order Runge-kutta method and relaxation method, we obtain the power distribution of pump light and signal
light along fiber by solving the steady-state rate equations in ytterbium-doped double-cladding fiber amplifier. The
relationships between the output power and the fiber length are discussed with different pump power and different doped
concentrations of the fiber. The change of the output power versus the pump power is calculated. The power distribution
along fiber and the relationship between output power and input power are analyzed when the signal is injected from z=L
and z=0 respectively.
A ring-cavity synchronously-pumped optical parametric oscillator was investigated, which was pumped by a
self-mode-locked Ti:sapphire laser. A periodically poled KTiOPO4 crystal was used in the oscillator, and the parametric
operation was obtained. The wavelength of the signal wave covered from 1000 nm to 1500 nm. The signal wave was
successfully frequency doubled by inserting a nonlinear BBO crystal in the cavity. The wavelength of second harmonic
could be tuned from 550 nm to 650 nm freely by cavity-length tuning. The loss of the cavity and the threshold of the
pump power, a thin glass substrate is inserted into the cavity to couple output the light, then the output power is
measured for varying pump power, based on the measurement the loss in the cavity was discussed. Furthermore, the
characteristic of output pulses is also measured.
On the basis of the analysis of material gain, a comprehensive optimization of quantum wells used in a 1-μm vertical-external-cavity surface-emitting laser was carried out. For a single-well structure, the optimized width lies between 8 and 10 nm, the optimized depth is a quantum well with ∼0.1 Al composition in AlGaAs barrier, and the optimized configurations are graded-index quantum well and quantum well with AlGaAs barrier and a GaAs buffer layer. The optimal width of a double- or triple-well structure lies between 6 and 8 nm. Compared to its single- and triple-well counterparts, double-well structure provides higher gain and has more tolerance to the deviation of laser wavelength.
We describe a synchronously-pumped optical parametric oscillator (OPO) based on periodically poled KTiOPO4(PPKTP). The OPO was pumped by a self-mode-locked Ti:sapphire laser. Its signal wave covers from 1070 nm to 1375
nm, and could be tuned freely by cavity-length tuning, the corresponding idler wave covering from 1.9 μm to 3.2 μm in
the mid-infrared region. Red, green and blue visible light were also generated by intra-cavity sum frequency or
frequency doubling. The threshold was measured to be about 250 mW at 810 nm pump. A thin glass substrate was
inserted to the cavity for output coupling, and the maximal output power was measured to be 26 mW. We adopted ring
cavity and linear cavity experimentally. After optimization, the output characteristics of the ring cavity and linear cavity
were investigated respectively. The approach to improve the output efficiency was also discussed.
The Optically pumped semiconductor disk laser use the InGaAs/GaAs quantum structures as the gain medium, and
optically pumped at 808 nm by the Laser Diode. We have got the fundamental output at 1030 nm, and its highest output
power is about 60 mW. Then, in straight cavity, we used LBO, KTP, KNbO3 as second harmonic generation crystal
respectively, and obtain the green laser with maximum power of 8 mW. In folding cavity, we employed LBO as second
harmonic generation crystal and got the laser at 515 nm with it's maximum power is 11mW. The characteristics of these
crystals were discussed. Finally, we simulated the heat distribution of the gain chip by finite-element analysis method,
and some measures of improving heat spread and output efficiency of the semiconductor chip.
An Ytterbium-doped double-cladding fiber laser is demonstrated. The threshold of the pump power is about 1.1W. The
maximum output power is 9.9W at the wavelength of 1045nm when the pump power is 15.3W. The slope efficiency is
around 70%. We discuss an exact numerical model, with a shooting method to solve the power steady-state equations.
Numerical results about the output power as a function of the pump power are in good agreement with measurements.
We present a tunable, high beam quality and narrow linewidth semiconductor disk laser. The maximum output power is 160 mW, and the slope efficiency is 22% using a gain chip without any postprocess under room temperature. When a 40-µm uncoated glass etalon is employed to tune the wavelength, the maximum output power of 110 mW, the tuning range of ~10 nm, the narrow linewidth of 0.07 nm, and the M2 factor of 1.03 are obtained. The tunability of the laser is theoretically analyzed, and the results are in good agreement with experiments.
A 1043nm semiconductor disk laser with a diamond heatspreader is presented. 880mW continuous-wave output power is
produced using a 3% output coupler with the incident pump power of 5900mW. The slope-efficiency is 16.7% and the
optical- to-optical conversion efficiency is 14.9%. The effect of the diamond heatspreader on the laser is also analyzed.
Here we demonstrate a supercontiuum spectrum generated in a tapered fiber pumped by a Ti sapphire laser with 130fs
pulse width at 800nm centre wavelength. The tapered fiber with the diameter of 1.25μm and the length of 16cm was
made by using a tapered machine. The supercontiuum range is from 500nm to 900nm. We simulated the
supercontinuum with the nonlinear Schrodinger Equation and discussed the affecting factors. In some conditions, the
experimental results are agreed very well with the theoretical analyses.
The edge emitting PL spectrum of semiconductor gain chip used in vertical external cavity surface emitting lasers was
theoretically calculated by using Lorenz linear function when considering of the intraband relaxation and the valence
band coupling. A model of laser output which considered of thermal effect was used to simulate our VECSELs' output
power. The theoretical results were in good agreement with the experimental results. The factors which influence the
output wavelength were discussed too.
A measurement of the leakage position using a distributed optical fiber acoustic sensor system based on Sagnac
interferometer was demonstrated here. The effect of the input polarization on the output power of the demodulated
signal was researched theoretically and experimentally. The influence of the polarization of the signal and the reference
on the measurement sensitivity was calculated. It is shown that a higher coherence between them could obtain a higher
measurement sensitive result; uprightness between them could not obtain any leakage signal. There are theoretical
analyses and experimental simulation in this paper. When the system is 10.044km-long, the least frequency measured
was 20 kHz and the calculated leakage position was 5-km, which was close to the real leakage position 5.022km. The
relative difference was 0.44%.
In this paper, we report a diode end pumped laser with a Yb3+-doped Ca4GdO(BO3)3 crystal (Yb:GdCOB). The
dopant concentration of the crystal was 7%. The crystal was pumped longitudinally at 976nm by a fiber-coupled
diode laser. The maximum output power of the laser emitted at 1.055um was 430mW, and the laser slope efficiency
was 75% with respect to the absorbed pump power. We also observed that the output power still increased when the
crystal no longer absorbed more pumped power (the crystal had been saturated). The possible reason may be that the
thermal lens effect changed the distribution of the laser mode. This will be discussed in part 3.
We present an optically pumped vertical external cavity surface emitting laser using the semiconductor gain chip composed of quantum wells. With a semiconductor saturable absorber mirror (SESAM), we obtained a Q-switched-like pulse output. The output power reached more than 3 mW at a center wavelength of 1007nm whose repetition frequency was 100 kHz and time bandwidth was 500ns. We discussed the possible reasons that the output power was lower compared with the CW operation. We also investigated the relationship between the intra-cavity intensity and the output pulse width. By designing the gain chip more carefully and increasing the pump power, it should be possible to obtain entirely mode-locking operation.
We present an optically pumped vertical external cavity surface emitting lasers using the semiconductor gain chip composed of quantum wells. The dependence of the spectrum of the output on the temperature of the gain chip was measured. The maximum output power reached 40mW at the wavelength of 1015.5nm with the pump power of 1.5W. The optical conversion efficiency reached 2.7%.
We present a diode-pumped Yb3+: YAl3(BO3)3 (Yb:YAB) laser system and measured the polarized outputs of the CW and femtosecond mode-locked lasers with semiconductor saturable-absorber mirrors (SESAM) at the fundamental wavelength. For the CW output, polarization ratios were 88.1% and 87.2% . For the mode-locked system, polarization ratio reached 38.5%.
This paper discusses the higher-order nonlinear terms: the third order dispersion and self-steepen effect the characteristics of femtosecond KLM laser, especially effect the pulse-width. The conclusion is that the pulse-width is proportional to the square root of the third order dispersion coefficient.
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