Pump-limited, 203 W, single-frequency monolithic fiber amplifier based on laser gain competition

We present high power results of a Yb-doped fiber amplifier seeded with a combination of broad and single-frequency laser signals. This two-tone concept was used in conjunction with externally applied or intrinsically formed thermal gradients to demonstrate combined stimulated Brillouin scattering suppression in a copumped monolithic, polarization-maintaining (PM) fiber. Depending on the input parameters and the thermal gradient, the output power of the single-frequency signal ranged from 80 to 203?W with slope efficiencies from 70% to 80%. The 203?W amplifier was pump limited and is, to the best of our knowledge, the highest reported in the literature for monolithic, PM single-frequency fiber amplifiers.     

100 W级全光纤化线偏振单频光纤放大器

报道了一种基于主振荡功率放大结构的全光纤化1064 mm线偏振单频光纤放大器。种子源是一个线宽约为3 kHz的单频光纤激光器。输出功率为50 mW的种子激光经两级掺Yb保偏双包层光纤(光纤纤芯直径分别为10 μm和20 μm)和一级手性耦合纤芯增益光纤放大后,最终获得了输出功率138 W、光束质量M2≤1.2、偏振消光比优于18 dB的高功率单频光纤激光输出。在脉冲调制模式下,获得了峰值功率465 W、脉宽宽度约为500 μs的线偏振单频光纤激光输出。     

Single-frequency, single-polarization ytterbium-doped fiber laser by self-injection locking

We demonstrated a stable single-frequency, single-polarization operation of ytterbium-doped fiber laser. As a novel practical method to realize single-polarization operation of fiber distributed Bragg reflector (DBR)laser, we proposed self-injection locking (SIL) with an active fiber ring feedback cavity. The laser has high output power exceeding 15 mW, wavelength of 1053.20 nm, and side-mode suppression ratio greater than 60 dB. The SIL fiber laser shows the improvements in output power and side-mode suppression compared with the fiber DBR laser. No mode-hopping is observed within 2 hours.     

Single-frequency thulium-doped distributed-feedback fiber laser

We have successfully demonstrated a single-frequency distributed-feedback (DFB) thulium-doped silica fiber laser emitting at a wavelength of 1735 nm. The laser cavity is less than 5 cm long and is formed by intracore UV-written Bragg gratings with a phase shift. The laser is pumped at 790 nm from a Ti:sapphire laser and has a threshold pump power of 59 mW. The laser has a maximum output power of 1 mW in a single-frequency, single-polarization radiation mode and is tunable over a few nanometers. To the best of the authors' knowledge, this is the first report of a single-frequency DFB fiber laser that uses thulium as the amplifying medium. The lasing wavelength is the longest demonstrated with DFB fiber lasers and yet is among the shortest obtained for thulium-doped silica fiber lasers.     

Single-frequency phosphate glass fiber laser with 100-mW output power at 1535 nm and its polarization characteristics

We demonstrate a high power single-frequency fiber laser. By using phosphate glass fiber as its gain media, the laser can achieve high output power of 100 mW in centimeter-long linear cavity. Single-frequency singlepolarization operation with 〈5 kHz linewidth and 65-dB signal-to-noise ratio （SNR） is realized by using external cavity polarization feedback technology.     

Multi-wavelength mode-locked Er/Yb Co-doped fiber laser with square nano-second pulse output

We report a multi-wavelength mode-locked Er/Yb codoped fiber laser with square nano-second pulse output, which is constructed with a “figure-of-eight” cavity structure. A section of polarization-maintaining Er/Yb co-doped double clad fiber was used as the gain medium and pumped by a fiber pigtailed multimode laser diode working at 975 nm via a multimode fiber combiner. Several megahertz repetition rate output pulses with peak power up to 9.2 W and pulse duration around several nanoseconds were obtained.     

Efficient operation of diode-pumped single-frequency thulium-doped fiber lasers near 2 micro m

Efficient operation of diode-pumped single-frequency fiber lasers at wavelengths from 1740 to 2017 nm has been demonstrated by using a very short piece of newly developed single-mode active fiber, i.e., heavily thulium-doped germanate glass fiber. At 1893 nm, the single-frequency fiber laser has a pump threshold of 30 mW, a slope efficiency of 35%, and maximum output power of 50 mW with respect to the launched power of single-mode pump diodes at 805 nm. To the best of our knowledge, this is the highest lasing efficiency achieved in single-frequency fiber lasers operating near 2 micro m. Frequency noise of the single-frequency fiber laser at 1893 nm has been characterized and compared with that of single-frequency fiber lasers at 1 and 1.55 micro m.     

1064nm超短腔DBR单频掺镱硅酸盐光纤激光器

提出了一种基于高掺杂硅酸盐增益光纤、输出波长为1 064nm的超短腔单频光纤激光器.该单频光纤激光器采用分布布拉格反射式腔型结构,有效腔长为2cm,其增益介质为1.1cm长的高浓度掺Yb3+光纤.通过恰当的温度控制,获得了线宽为4.8kHz的稳定单频激光输出.当注入泵浦光为378mW时,输出功率为13mW,斜效率为3.4%.在频率大于1 MHz时,测得该光纤激光器的相对噪声强度值约为-132dB/Hz.采用主振荡功率放大结构,对该单频光纤激光器的输出功率进行放大.当放大增益光纤长度选取为56cm时,得到了325mW的最大输出功率,其斜效率为52.8%.     

Monochromatization of semiconductor laser diodes using one-dimensional photonic crystals

The results on the development of the single-frequency semiconductor laser with external cavity based on a fiber Bragg grating (one-dimensional photonic crystal) formed in a single-mode fiber waveguide are presented. Stable single-frequency lasing at a wavelength of 977 nm with a spectral half width of 0.2 nm is achieved with a laser power output of 350 mW. The temperature dependence of lasing parameters is studied.     

Er-doped photonic crystal fiber amplifier with 70 W of output power

We report for the first time, to the best of our knowledge, on a large mode area Er-doped photonic crystal fiber laser system. The fiber core had a diameter of 40 μm and NA of <0.04 leading to a mode field diameter of about 31 μm around 1550 nm wavelength. More than 70 W of single-frequency output power at 1556 nm could be extracted using a master-oscillator power-amplifier scheme. Near diffraction limited output beam quality has been verified by measuring the TEM(00) content with a nonconfocal scanning ring cavity.     

Wavelength tunable high power laser using a double-clad Er:Yb doped fiber

We experimentally demonstrated a stable, wavelength-tunable fiber laser using a polarization-maintaining, double-clad Er:Yb doped fiber amplifier in the cavity. The output wavelength is tunable over the range from 1535 to 1567 nm using a fixed grating and the dichroic mirror placed on a rotational mount; under rotation of the dichroic mirror the tuning ratio of 50 nm/deg was found. We studied the wavelength tuning range dependence on the amplifier fiber length and achieved a maximal output power of 850 mW. This configuration can be Q-switched for high peak power and its narrow bandwidth is suitable for nonlinear optics applications, such as parametric teraherthz generator.     

Efficient single-axial-mode operation of a Ho:YAG ring laser pumped by a Tm-doped silica fiber laser

Efficient single-frequency operation of a Ho:YAG ring laser at room temperature with a traveling-wave TeO2 acousto-optic modulator to enforce unidirectional operation is reported. By use of a 2-at. % Ho3+-doped 10-mm-long Ho:YAG rod, end pumped by a cladding-pumped tunable Tm-doped silica fiber operating at 1.9 microm, the Ho:YAG ring laser yielded 3.7 W of single-frequency output at 2.1 microm in a diffraction-limited TEM00 beam with M2 < 1.1 for an incident pump power of 8.8 W. The rf power required for unidirectional operation was 0.3 W and corresponded to an increase in cavity loss for the lasing direction (due to diffraction) of only 0.5%. The prospects for further improvement in efficiency are discussed.     

29.2 W, 20 kHz linewidth all fiber single-frequency MOPA laser

We demonstrate a high power all fiber single-frequency MOPA laser. The center wavelength of the single-frequency fiber laser seed is 1064 nm with a linewidth narrower than 20 kHz. A two-stage power amplification configuration is employed. A single-frequency fiber laser with an output power of 29.2 W is obtained, and the optical to optical efficiency is 78%.     

全光纤结构高功率主振荡功率放大型单频光纤激光器

研制了一台全光纤结构主振荡功率放大型掺镱单频光纤激光器。该光纤激光器包括种子激光器和级联放大器两部分。种子激光器是自行搭建的环形腔结构的单频窄线宽光纤激光器。在976 nm半导体激光器泵浦下,能够输出线宽为10 MHz量级、波长为1 079.88 nm的单频光,激光功率为10.02 W,光-光转化效率为58.9%,斜率效率为65.3%。     

122-W high-power single-frequency MOPA fiber laser in all-fiber format

We demonstrate a high-power single-frequency master oscillator power amplifier (MOPA) fiber laser.The central wavelength of the single-frequency fiber laser seed is 1 063.8 nm,with a linewidth narrower than 20 kHz and output power of 120 mW.By using two-stage amplification,a single-frequency fiber laser with an output power of 122 W is obtained,and the optical-optical conversion efficiency is 72%.No significant amplified spontaneous emission (ASE) or stimulated Brillouin scattering (SBS) is observed.The output power can be further increased by launching more pump power.     

二波混频高功率单频窄线宽光纤激光器

设计并制造了一种基于二波混频的高功率单频窄线宽光纤激光器.激光器采用长线形腔结构,以Er3+/Yb3+双包层光纤作为增益介质,利用输出信号光分束反馈注入,与腔内振荡激光混频干涉,形成分布的增益光栅与折射率光栅共同作用选模,获得稳定的1550.63 nm单频高功率激光输出.在975 nm多模激光二极管(LD)抽运下,激光...     

Microwave generation using an all polarization-maintaining linear cavity dual-wavelength fiber laser with tunable wavelength spacing

A stable dual-wavelength erbium-doped fiber laser with a linear cavity is formed by a polarization-maintaining uniform fiber Bragg grating (PM-FBG) and a polarization-maintaining linearly chirped fiber Bragg grating (PM-LCFBG), both of which were fabricated on a high-birefringence (Hi-Bi) fiber. Experimental results show stable dual-wavelength lasing operation with a wavelength separation of ∼0.22 nm, which can be tuned down to as small as 0.05 nm and a large optical signal-to-noise ratio (OSNR) of over 40 dB under room-temperature. Microwave signal at frequency of 9.41, 18.03 and 27.46 GHz is achieved by heterodyned the output lasing wavelengths on a photodetector.     

High-sensitivity mode-locked fiber laser gyroscope

We report significant performance improvement of a mode-locked fiber laser gyroscope. A Fabry-Perot cavity GaAlAs laser diode whose front facet was antireflection coated was used as a gain medium. The rms noise equivalent rotation rate measured with a time-interval counter was improved to 0.06deg/ radicalh. The long-term drift of the gyroscope signal was reduced to 100deg/ radicalh after a polarizer was inserted into the laser cavity formed with a polarization-maintaining fiber.     

96.2 W all-fiberized nanosecond single-frequency fiber MOPA

We report experimental results on a 96.2 W all-fiberized nanosecond single-frequency masteroscillator power amplifier (MOPA) laser working at 1064 nm. An external modulation fiber laser with average power of 0.5 mW and line width of 20 kHz is used as the seed source. Amplifying the seed laser in four stages, a single-frequency laser with pulse duration of 10 ns and peak power of 816.7 W is obtained. The average output power is up to 96.2 W. Further power-scaling of this MOPA structure can be realized since our experiment is only pump-power limited.     

Specifics of Bragg gratings inscription and characterization in polarization-maintaining Yb-doped fiber for DFB lasers

Fiber Bragg gratings (FBGs) with a length of about 4 cm and a phase shift of about π are written in the polarization-maintaining fiber doped with ytterbium ions. A tunable polarized single-frequency laser is employed for the measurement of the FBG reflection spectrum. A relatively high spectral resolution allows the estimation of the FBG parameters. Polarized single-frequency ytterbium-doped distributed-feedback (DFB) fiber lasers radiated at about 1.1 μm are constructed using the written FBGs. The passive line width of the laser radiation (about 50 kHz) is estimated from the beat spectrum of the two DFB lasers.