大功率低阈值980nm单模AlGaInAs/AlGaAs量子阱激光器

To achieve low threshold current as well as high single mode output power,a graded index separate confinement heterostructure(GRIN-SCH)AlGaInAs/AlGaAs quantum well laser with an optimized ridge waveguide was fabricated.The threshold current was reduced to 8 mA.An output power of 76 mW was achieved at100 mA current at room temperature,with a slope efficiency of 0.83 W/A and a horizon divergent angle of 6.3.The maximum single mode output power of the device reached as high as 450 mW.     

High power single mode 980 nm AIGalnAs/AIGaAs quantum well lasers with a very low threshold current

To achieve low threshold current as well as high single mode output power, a graded index separate confinement heterostructure （GRIN-SCH） A1GaInAs/A1GaAs quantum well laser with an optimized ridge wave- guide was fabricated. The threshold current was reduced to 8 mA. An output power of 76 mW was achieved at 100 mA current at room temperature, with a slope efficiency of 0.83 W/A and a horizon divergent angle of 6.3°. The maximum single mode output power of the device reached as high as 450 mW.     

Room temperature continuous wave operation of quantum cascade laser at λ～ 9.4μm

Continuous wave (CW) operation of long wave infrared (LWIR) quantum cascade lasers (QCLs) is achieved up to a temperature of 303 K.For room temperature CW operation,the wafer with 35 stages was processed into buried heterostructure lasers.For a 2-mm-long and 10-μm-wide laser with high-reflectivity (HR) coating on the rear facet,CW output power of 45 mW at 283 K and 9 mW at 303 K is obtained.The lasing wavelength is around 9.4μm locating in the LWIR spectrum range.     

InAsSb/InAsSbP double-heterostructure lasers emitting at 3–4 µm: Part I

Previous publications concerned with the development and investigation of InAsSb/InAsSbP double heterostructure lasers emitting at 3–4 μm fabricated by liquid phase epitaxy are reviewed. In pulsed mode, the maximum operating temperature of the lasers is 203 K, the characteristic temperature is 35 K, and differential quantum efficiency is 20±5% at 77K. Mesa-stripe lasers with a 10-to 30-μm stripe width and a 200-to 500-μm cavity length can operate in CW mode up to 110 K. The total optical output power of more than 10 mW at λ=3.6 μm is obtained at T=82 K in CW mode. The output power per mode does not exceed 2 mW/facet. A single-mode lasing is achieved in the temperature range of 12–90 K. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 34, No. 11, 2000, pp. 1396–1403. Original Russian Text Copyright ? 2000 by Danilova, Imenkov, Sherstnev, Yakovlev.     

A high-power tapered and cascaded active multimode interferometer semiconductor laser diode

A high power semiconductor laser diode with a tapered and cascaded active multimode interferometer (MMI) cavity was designed and demonstrated.An output power as high as 32 mW was obtained for the novel laser diode with a tapered and cascaded active MMI cavity,being much higher than the 9.8 mW output power of the conventional single ridge F-P laser with the same material structure and the same device length due to the larger active area;and also being higher than the 21.2 mW output power of the rectangular and cascaded active MMI laser diode with nearly the same structure,except for the shape of the MMI area.In addition,the tapered and cascaded active multimode interferometer laser showed stable single mode outputs up to the maximum output power.     

Distributed feedback quantum cascade lasers operating in continuous-wave mode at λ≈7.6μm

正Distributed feedback(DFB) quantum cascade lasers(QCLs) in continuous-wave(CW) mode emitting atλ≈7.6μm are presented.Holographic lithography was used to fabricate the first-order distributed feedback grating. For a high-reflectivity-coated QCL with 14.5-μm-wide and 3-mm-long cavity,CW output powers of 300 mW at 85 K and still 10 mW at 270 K are obtained.Single-mode emission with a side-mode suppression ratio(SMSR) of about 30 dB and a wide tuning range of ~300 nm in the temperature range from 85 to 280 K is observed.     

A green laser at 517 nm based on intracavity frequency doubling of the diode-pumped Yb:LO laser

We report for the first time, to our knowledge, the diode-pumped continuous-wave （CW） thin-disk Yba＋-doped Lu203 （Yb：LO） laser at 1 034 nm and the second-harmonic generation at 517 nm. With a 6.3% output coupler, the maximum output power is 1.17 W under a pump power of 18.5 W. Moreover, the intracavity second-harmonic generation （SHG） is also -achieved with power of 193 mW at 517 nm by using an LiB305 （LBO） nonlinear crystal. The beam quality fac- tor M2 is about 1.28. The fluctuation of the output power is about 3% in 1 h.     

Study on the Pr:KYF ultraviolet laser at 305 nm pumped by blue laser

An all-solid-state Pr:KY3F10(Pr:KYF) laser pumped by blue laser(471 nm) has been demonstrated.With the incident pump power of 2.6 W,the maximum output power at 610 nm is 213 mW.Moreover,the intracavity second-harmonic generation(SHG) is also achieved with the maximum ultraviolet(UV) power at 305 nm of 11 mW by using a β-BaB2O4(BBO) nonlinear crystal.     

1400—1500nm．Different Material-doped Raman Fiber Lasers Pumped by Nd：YVO4 Laser

Different material-doped Raman fiber lasers with very high efficiency operatingin continuous-wave are presented. With 1 W Nd :YVO4 laser pumping at wavelength of 1342 nm,single mode output power of above 500 mW (optical-to-optical conversion efficiency of 50%) is simulated in the range of 1 400-1500 nm. Using high-germanium,phosphate and high- borate silicate fibers as the gain medium, laser output at wavelengths of 1 420,1450,1480 and 1495 nm can be achieved with different geometries, which are just as pumping C-band and L-band distributed Raman fiber amplifiers.     

1400-1500 nm,Different Material-doped Raman Fiber Lasers Pumped by Nd∶YVO_4 Laser

Different material-doped Raman fiber lasers with very high efficiency operating in continuous-wave are presented.With 1 W Nd∶YVO 4 laser pumping at wavelength of 1 342 nm, single mode output power of above 500 mW (optical-to-optical conversion efficiency of 50%) is simulated in the range of 1 400-1 500 nm.Using high-germanium,high-phosphate and high-borate silicate fibers as the gain medium,laser output at wavelengths of 1 420,1 450,1 480 and 1 495 nm can be achieved with different geometries,which are just as pumping C-band and L-band distributed Raman fiber amplifiers.     

一种平均电流模式控制的单电感双输出型开关电源转换器

An integrated single-inductor dual-output （SIDO） switching DC-DC converter is presented. The outputs are specified with 1.2 V/400 mA and 1.8 V/200 mA. A decoupling small signal model is proposed to analyze the multi-loop system and to design the on-chip compensators. An average current control mode is introduced with lossless, continuous current detection. The converter has been fabricated in a 0.25μm 2P4M CMOS process. The power efficiency is 86% at a total output power of 840 mW while the output ripples are about 40 mV at an oscillator frequency of 600 kHz.     

The simulation of thermal characteristics of 980 nm vertical cavity surface emitting lasers

In order to design a single mode 980 nm vertical cavity surface emitting laser (VCSEL),a 2μm output aperture is designed to guarantee the single mode output.The effects of different mesa sizes on the lattice temperature,the output power and the voltage are simulated under the condition of continuous working at room temperature,to obtain the optimum process parameters of mesa.It is obtained by results of the crosslight simulation software that the sizes of mesa radius are between 9.5 to 12.5μm,which cannot only obtain the maximum output power,but also improve the heat dissipation of the device.     

A dual mode charge pump with adaptive output used in a class G audio power amplifier

A dual mode charge pump to produce an adaptive power supply for a class G audio power amplifier is presented.According to the amplitude of the input signals,the charge pump has two level output voltage rails available to save power.It operates both in current mode at high output load and in pulse frequency modulation (PFM) at light load to reduce the power dissipation.Also,dynamic adjustment of the power stage transistor size based on load current at the PFM mode is introduced to reduce the output voltage ripple and prevent the switching frequency from audio range.The prototype is implemented in 0.18μm 3.3 V CMOS technology.Experimental results show that the maximum power efficiency of the charge pump is 79.5%@ 0.5x mode and 83.6%@ lx mode.The output voltage ripple is less than 15 mV while providing 120 mA of the load current at PFM control and less than 18 mV while providing 300 mA of the load current at current mode control.An analytical model for ripple voltage and efficiency calculation of the proposed PFM control demonstrates reasonable agreement with measured results.     

垂直腔面发射激光器

The development and application of vertical-cavity surface-emitting lasers (VCSELs) are summarized in this paper. The emphasis is focused on the high power single and 2-D arrays bottom-emitting VCSELs with a wavelength of 980nm. A distinguished device performance is achieved. The maximum continuous-wave (CW) output power of large aperture single devices with active diameters up to 500μm is as high as 1.95W at room temperature, which is to our knowledge the highest value reported for a single device. Size dependence of the output power, the threshold current and the differential resistance are discussed. A 16 elements array with 200μm aperture size (250μm center spacing) of individual elements shows a CW output power of 1.32W at room temperature.     

Dual-wavelength Q-switched erbium-doped fiber laser using an SMF-MMF-SMF structure and graphene oxide

We have successfully demonstrated a stable dual-wavelength Q-switched erbium-doped fiber laser (EDFL) using a single mode fiber-multimode fiber-single mode fiber (SMF-MMF-SMF) structure-based filter. Using a graphene oxide (GO) saturable absorber (SA) to modulate the cavity loss, passive Q-switching of the dual-wavelength laser is achieved at 1 549.6 nm and 1 558.6 nm. The laser recorded the shortest pulse width of about 2.9 μs, the maximum pulse repetition rate of 65.27 kHz and the maximum average output power of 0.99 mW at pump power of 225.1 mW. The present laser has the maximum pulse energy of 15.17 nJ. A 2 SMF-MMF-SMF structure has been experimentally confirmed to be very promising as a wavelength filter.     

Laser-diode pumped Nd: GdVO4 ultraviolet laser with LBO frequency tripling

We have demonstrated a laser-diode pumped Nd.GdVO4 extra-cavity frequency tripling ultraviolet laser with a LBO crystal in this paper. Under the acousto-optic （A-O） Q-switched operation, we have obtained 355 nm ultraviolet laser,with pulse width of 25 ns and pulse repetition rate of 20 kHz. By using a type Ⅰ non-critical phase-matched LBO crystal, the SHG output power of 822 mW is achieved at the incident pump power of 16 W. The output power of 355nm UV laser is 260mW with a type Ⅱ phase-matched LBO crystal,and the conversion efficiency （1 064 nm-355 nm） is 5.9 %. The power stability of 355 nm laser is 1.7% in 1 h.     

Diode-pumped Q-switched Extra-cavity Frequency-dou bled Nd∶YVO_4/KTP Green Laser

A diode-pumped acousto-op ti cal(A-O) Q-switched extra-cavity frequency-doubled Nd∶YVO_ 4/ KTP (KTiO PO_ 4) green laser formed with a simple plane-plane cavity has been demonst rated. With the incident pump power of 12.7 W, A-O Q-switched average output power at 1 064 nm was 3.81 W with a duration of 25 ns at a repetition rate of 20 kHz, extra-cavity frequency doubling with KTP as the nonlinear crystal y ielded the maximum output power of 1.92 W at 532 nm, the corresponding optical conversion efficiency from 1 064 nm to 532 nm light is 50.4%. The continuous -wave(CW) laser properties of diode-pumped Nd∶YVO_ 4 crystal operating at 1 064 nm have been studied. With the incident pump power of 25 W, the maximu m CW output power of 13.81 W was obtained with the corresponding optical conver sion efficiency of 55.24%.     

Gold nanoparticles film for Q-switched pulse generation in thulium doped fiber laser cavity

Passively Q-switched thulium doped fiber laser (TDFL) has been successfully demonstrated using gold nanoparticles (GNPs), which were embedded into polyvinyl alcohol as saturable absorber (SA). The stable self-starting Q-switched laser was generated to operate at 1 891 nm when a tiny piece of the prepared film was slot in between two fiber ferrules and incorporated into the laser cavity. The repetition rate can be adjusted from 48.54 kHz to 49.64 kHz while the pulse width decreased from 3.52 μs to 2.38 μs with the increase of 1 550 nm pump power from 840 mW to 930 mW. The corresponding pump power output power linearly increased from 3.62 mW to 6.3 mW with a slope efficiency of 2.53%. The maximum peak power and pulse energy were recorded at about 39 mW and 0.12 µJ, respectively at pump power of 930 mW. The Q-switching operation was caused by the surface plasmon resonance absorption of GNPs.     

Difference mode generation in injection lasers

The nonlinear generation of a difference mode in an injection laser is considered. A new design based on the InGaP/GaAs/InGaAs heterostructure is suggested in order to generate two laser modes with a wavelength of about 1 μm and a difference mode at a wavelength of about 10 μm. In lasers with a 100-μm-wide waveguide, the power output of the difference mode can be as high as ∼10 mW at ∼10 W in the short-wavelength modes. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 35, No. 10, 2001, pp. 1256–1260. Original Russian Text Copyright ? 2001 by Aleshkin, Afonenko, Zvonkov.     

Diode-end-pumped Nd：YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave(CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd:YVO4 and using LBO as the intra-cavity SHG crystal.With the optimization of laser cavity and crystal parameters,the laser operates at a very high efficiency.When the pumping power is about 31 W,the output at 457 nm reaches 4.2 W,and the optical to optical conversion efficiency is about 13.5% accordingly.The stability of the output power is better than 1.2% for 8 h continuously working.