A pump power controlled 1,060 nm multiwavelength fiber ring laser using nonlinear polarization rotation of SOA

We propose and experimentally demonstrate a both channel spacing and wavelength-tunable 1,060 nm multiwavelength fiber laser using nonlinear polarization rotation of semiconductor optical amplifier (SOA). The SOA in the cavity can not only provide the gain but also generate a pump power controlled phase-shift between two orthogonal linear states of polarization. The experimental result shows that the fast and continuous wavelength tuning is achieved with external light injection, while the channel spacing of the multiwavelength laser can be varied by adjusting the length of polarization maintaining fiber. When an external laser source with 13 dBm power is injected into the SOA as a control pump, optically tunable operation of up to 20 wavelength channels, from 1,042 to 1,058 nm, with a wavelength spacing of 0.8 nm has been demonstrated with the signal-to-spontaneous-noise ratio over 40 dB at room temperature. The lasers are stable with a maximum power fluctuation per channel of less than 0.5 dB during 2-h test.     

2-μm single longitudinal mode GaSb-based laterally coupled distributed feedback laser with regrowth-free shallow-etched gratings by interference lithography

We report a type-I Ga Sb-based laterally coupled distributed-feedback(LC-DFB) laser with shallow-etched gratings operating a continuous wave at room temperature without re-growth process. Second-order Bragg gratings are fabricated alongside the ridge waveguide by interference lithography. Index-coupled LC-DFB laser with a cavity of 1500 μm achieves single longitudinal mode continuous-wave operation at 20℃ with side mode suppression ratio(SMSR) as high as 24 dB.The maximum single mode continuous-wave output power is about 10 mW at room temperature(uncoated facet). A low threshold current density of 230 A/cm~2 is achieved with differential quantum efficiency estimated to be 93 mW/A. The laser shows a good wavelength stability against drive current and working temperature.     

A stable and tunable linear polarization single longitudinal mode fiber ring laser

A stable and tunable linear polarization single longitudinal mode fiber ring laser is proposed and demonstrated. A high extinction ratio spatial mode interference filter utilizing two-mode graded-index fiber supresses irregular side modes effectively, the combination of fiber polarizer and polarization maintaining fiber act as a polarization dependent comb filter, and tunable bandpass filter is adopted to select proper lasing wavelength. The power fluctuation and wavelength fluctuation at 1549.88 nm are less than 0.05 dB and 0.02 nm in 1 h, respectively. Only one longitudinal mode appears within a free spectral range of 7.5 GHz, and the degree of polarization in percentage is approximately as high as 99.07%.     

Narrowband, mid-infrared, seeded optical parametric generator based on non-critical CdSiP2 pumped by 120-ps, single longitudinal mode 1,064 nm pulses

In this work, we present low-threshold, efficient optical parametric generation in CdSiP₂ pumping at 1,064 nm with 120-ps-long, single longitudinal and transverse mode pulses at 230-kHz repetition rate provided by a microchip passively Q-switched master-oscillator power amplifier laser system. Seeding at the signal wavelength with a laser diode, we generated bandwidth-limited idler pulses at 6,100 nm.     

Diode-pumped orthogonally polarized dual-wavelength Nd3+:LaBO2MoO4 laser

Polarized spectroscopic properties related to 1.07 μm laser operation of a 1.8 at.% Nd³⁺:LaBO₂MoO₄ crystal grown by the Czochralski method were investigated at room temperature. Using a 2.2-mm-thick, Z-cut Nd³⁺:LaBO₂MoO₄ crystal as gain medium, orthogonally polarized dual-wavelength laser at 1,068 and 1,074 nm was first realized in a plano-concave resonator end-pumped by a quasi-continuous-wave 795 nm diode laser. A total output peak power of 1.2 W with slope efficiency of 26 % around 1.07 μm was obtained. The influences of resonator length and pump power on output laser wavelength were also investigated.     

High repetition rate,Q-switched Ho:YAG laser resonantly pumped by a 20 W linearly polarized Tm: fiber laser

We describe an efficient, low-threshold, continuous-wave (CW) and Q-switched operation of a Ho:YAG laser resonantly, single-pass pumped by a 20 W linearly polarized narrow line width Tm: fiber laser at the wavelength of 1,908 nm. At room temperature for an output coupler of 30 % transmission, a maximum continuous-wave output power of 13.3 W for 18.9 W of absorbed pump power was achieved, corresponding to a slope efficiency of 73 %. In a quasi continuous-wave pumping regime, for several output couplers slope efficiencies of almost 82 % were observed. For a Q-switched operation, a Brewster-cut acousto-optic modulator was used. In a CW pumping regime, the pulse repetition frequency (PRF) was changed from 4 to 15 kHz. Under a Q-switched operation, the maximum output power of 12.25 W in relation to 15 kHz PRF was obtained; however, the maximum peak power of almost 250 kW at the PRF of 4 kHz was demonstrated. In the best case, for 4 kHz PRF, pulse energies of 2.18 mJ with a 8.8 ns FWHM pulse width (one of the shortest pulse durations observed in holmium-doped Q-switched lasers) were achieved. The laser operated at the wavelength of 2,090.23 nm with the FWHM line width of 0.95 nm. The beam quality factor of M ² was measured to be below 1.42 in both X and Y axis.     

Stabilization of a multiwavelength erbium-doped fiber laser using a nonlinear silicon waveguide

We propose and demonstrate a multiwavelength erbium-doped fiber laser stabilized by four-wave mixing (FWM) in a nonlinear silicon-on-insulator (SOI) waveguide. The optical gain was provided by an erbium-doped fiber amplifier, and the wavelength selectivity was achieved by a Fabry–Pérot comb filter in the ring cavity. The FWM in the SOI waveguide was enhanced by applying a reverse-biased p-i-n diode structure to reduce free-carrier absorption. Making use of the nonlinearity of the SOI waveguide, a multiwavelength laser with six output wavelengths at 0.8 nm spacing was achieved. The power difference among modes was equalized within a range of 1.8 dB. The power fluctuation of each mode was stabilized to <0.65 dB during 20 min observation at room temperature.     

Simulation of InGaN violet and ultraviolet multiple-quantum-well laser diodes

Optical properties of the InGaN violet and ultraviolet multiple-quantum-well laser diodes are numerically studied with a self-consistent simulation program. Specifically, the performance of the laser diodes of various active region structures, operating in a spectral range from 385 to 410 nm, are investigated and compared. The simulation results indicate that the double-quantum-well laser structure with a peak emission wavelength of 385–410 nm has the lowest threshold current. The characteristic temperature of the single-quantum-well laser structure increases as the peak emission wavelength increases. The triple-quantum-well structure has the largest characteristic temperature when the peak emission wavelength is shorter than 405 nm, while the double-quantum-well structure possesses the largest characteristic temperature when the peak emission wavelength is larger than 405 nm.     

MBE-grown Ridge-waveguide InGaAs/InGaAsP Strained Quantum Well Lasers at 2 μm Wavelength

1 horottionFor a long time GaSh--based IILV antimonial material is the main material systemfor nddinfrared semiconductor l...[l' 2] because of its wide wavelength range Of 1. 7 4. 5 mp offering a convenient choice for different applications. HOwever there aredifficuhies in its material growth and device fabrication. Iall--based InGaAs/InGaAsPstrained QW Inaterial become attractive for nddinfrared semiconductor lasers because ithas relatively loW thermcrresistance and serial resistance a…     

MBE-grown Ridge-waveguide InGaAs/InGaAsP Strained Quantum Well Lasers at 2 μm Wavelength

The result of molecular beam epitaxy (MBE)-grown ridge-waveguide InGaAs/ InGaAsP/InP strained quantum well lasers at 2 μm wavelength is reported. The pulsed electrical luminescence spectrum at room temperature is observed with peak wavelength of about 1.98 μm. At 77 K the lasers become lasing in pulse regime, with threshold current of about 18～30 mA, peak wavelength of about 1.87～ 1. 91 μm, and single longitudinal mode operation in the current range of 160～230 mA.     

A dual-pass Mach–Zehnder interferometer filter using a TCF loop mirror for double-wavelength fiber lasers

A dual-pass Mach–Zehnder interferometer filter using a section of twin-core fiber (TCF) loop mirror is proposed. The filter is theoretically and experimentally studied for various interferometer arm difference when TCF length is constant. Theoretical results are validated by the experimental demonstration and in good agreement with the experimental results. And then, by using the filter in a ring fiber laser, a stable and switchable dual-wavelength lasing is obtained experimentally. The 3-dB bandwidth and the SMSR of the output laser are 0.015 nm and higher than 62.4 dB, respectively. The peak power fluctuation and wavelength shift are also monitored to be less than 0.04 dB and 0.02 nm over an hour at room temperature. Furthermore, the output laser can be switched between single and dual wavelength by carefully adjusting the PCs. The experimental results show that the filter can suppress mode competition effectively, improve the SMSR availably, and enhance the stability of the output lasing.     

Si homojunction structured near-infrared laser based on a phonon-assisted process

We fabricated several near-infrared Si laser devices (wavelength ～1300 nm) showing continuous-wave oscillation at room temperature by using a phonon-assisted process induced by dressed photons. Their optical resonators were formed of ridge waveguides with a width of 10 μm and a thickness of 2 μm, with two cleaved facets, and the resonator lengths were 250–1000 μm. The oscillation threshold currents of these Si lasers were 50–60 mA. From near-field and far-field images of the optical radiation pattern, we observed the high directivity which is characteristic of a laser beam. Typical values of the threshold current density for laser oscillation, the ratio of powers in the TE polarization and TM polarization during oscillation, the optical output power at a current of 60 mA, and the external differential quantum efficiency were 1.1–2.0 kA/cm², 8:1, 50 μW, and 1 %, respectively.     

Room temperature efficient continuous wave and Q-switched operation of a Ho:YAP laser

We report the continuous wave and acousto-optically Q-switched operation of a Tm:YLF-pumped Ho:YAP laser at room temperature. Continuous wave output power of 6.8 W at 2118 nm was obtained under the incident pump power of 13.4 W, corresponding to a slope efficiency of 65.6% and a conversion efficiency of 50.7%. For the Q-switched mode, a maximum pulse energy of 1.28 mJ and a minimum pulse width of 31 ns at the repetition rate of 5 kHz were achieved, resulting in a peak power of 41.3 kW. In addition, the Ho:YAP laser was employed as a pumping source of ZGP optical parametric oscillator, the total average output power of which was 3.2 W at 4.08 and 4.41 μm with a slope efficiency of 69.5%, corresponding to the diode-to-mid-IR conversion efficiency of 9.0%.     

Five-hundred-milliwatts distributed-feedback diode laser emitting at 940 nm

A DFB laser emitting at a wavelength around 940 nm in a single longitudinal mode up to an output power of 500 mW with a side mode suppression ratio greater than 50 dB is presented. More than 4 nm tuning range was reached by varying the current between 100 and 800 mA. Up to a power of about 300 mW, the lateral far field revealed stable fundamental mode operation.     

双波长二极管合束端面抽运掺镨氟化钇锂单纵模360nm紫外激光器

报道了一种双波长半导体激光二极管(LD)合束端面抽运掺镨氟化钇锂晶体(Pr~(3+):LiYF_4)全固态、单纵模360nm紫外激光器.该激光器采用V形折叠腔结构,利用反射式体布拉格光栅作为波长选择反射镜来压缩光谱线宽,与法布里-珀罗(F-P)标准具组合构成窄带滤波器进行单纵模的有效选取,通过Ⅰ类位相匹配切割的倍频晶体三硼酸锂对腔内720nm基频光进行倍频.在444nmLD输出功率为1200mW和469nmLD输出功率为1400mW时,合束抽运获得了功率为112mW的连续单纵模360nm紫外激光稳定输出,光-光转换效率为4.3%.测量结果表明,边摸抑制比大于60dB,4h功率均方根值稳定性优于0.5%,1h频率漂移小于220MHz,激光振幅噪声小于0.5%.     

基于偏振保持掺Er3+光纤的高稳定性单波长光纤激光器

研制出光敏偏振保持掺Er³⁺光纤,通过在这种光纤上紫外写入三个光纤光栅,形成对抽运激光高转化效率的谐振腔.在输出功率为23.617dBm、工作波长为976nm的激光抽运下,得到均值功率为9.20dBm、均值中心波长为1554.554nm的单波长激光输出.在室温下800min（约13.3h）的测量时间内,其输出功率的波动为±0.05dB,中心工作波长的波动为±0.0015nm. 关键词： 光纤激光器 3+光纤')" href="#">偏振保持掺Er³⁺光纤 光纤Bragg光栅     

Multi-peak tunable CW orange laser based on single-pass sum frequency generation in step-chirped MgO: PPLN

We report an all-solid-state tunable CW orange laser based on single-pass sum-frequency generation in step-chirped PPMgO: LN crystal. Two laser sources, a tunable laser (1550 nm) and an ASE laser (1525–1650 nm) are used interchangeably as pumps and mixed with a fixed 975 nm signal laser. Up to 4.3 mW at 597 nm is generated corresponding to 0.87% nonlinear conversion efficiency and the beam quality (M²) value of about 2.5 is measured. The output wavelength can be tuned up to?~?5.66 nm by varying the position of focusing inside the crystal and by temperature, which makes possible the practical application of our device for wavelength selection and diversity in the orange spectral range.     

Laser radiation effects on optical and structural properties of nanostructure CdSe thin film

Cadmium selenide (CdSe) thin films were deposited on a glass substrate using the thermal evaporation method at room temperature. The changes in the optical properties (optical band gap and absorption coefficient) after irradiation by TEA N₂ laser at different energies were measured in the wavelength range 190–800 nm using a spectrophotometer. It was found that the optical band gap is decreased after irradiating the thin films. The samples were characterized using X-ray diffraction (XRD), and the grain size of the CdSe thin film was calculated from XRD data, which was found to be 41.47 nm as-deposited. It was also found that grain size increases with laser exposure. The samples were characterized using a scanning electron microscope and it was found that big clusters were formed after irradiation by TEA N₂ laser.     

单频窄线宽分布布拉格反射光纤激光器研究

分析了单频窄线宽分布布拉格反射（DBR）光纤激光器的单模工作条件,在此基础上算出单模工作区域,制作了一个单频窄线宽分布布拉格反射光纤激光器。该激光器在波长为975.5nm的半导体激光器抽动下,在1556.91nm波长处。当抽运功率为55.35mW时输出功率可达1.43mW,频宽小于1.2MHz(受测量仪器分辨率限制）。经测量,该输出激光是稳定的单纵模输出。     

Silver nanoparticles produced by PLD in vacuum: role of the laser wavelength used

In this work we report the results of investigation of silver (Ag) nanoparticles prepared on a silica substrate by laser ablation. Our attention was focused on the mean diameter, size distribution and optical absorption properties of nanoparticles prepared in vacuum by using different laser wavelengths. The fundamental wavelength and the second, third, and fourth harmonics of a nanosecond Nd:YAG laser were used for nanoparticles fabrication. The corresponding values of the laser fluence for each wavelength were: 0.6 J/cm² at 266 nm, 0.8 J/cm² at 355 nm, 2.8 J/cm² at 532 nm, and 2 J/cm² at 1064 nm. The Ag nanoparticles produced have mean diameters in the range from 2 nm to 12 nm as the nanoparticles’ size decreases with the decrease of the wavelength used. The presence of the Ag nanoparticles was also evidenced by the appearance of a strong optical absorption band in the measured UV-VIS spectra associated with surface plasmon resonance (SPR). A redshift and widening of the absorption peak were observed as the laser wavelength was increased. Some additional investigations were performed in order to clarify the structure of the Ag nanoparticles.