Acousto-optic Q-switched cladding-pumped ytterbium-doped fiber laser

A diode-pumped, acousto-optic Q-switched fiber laser is presented based on multimode ytterbium-doped fiber. The fiber with core diameter of 30 μm is used to increase the laser gain volume and the pulse energy efficiently. The average power in excess of 9 W is obtained at the repetition rate of 20 kHz with 66% slope efficiency. The pulse width is 198 ns with no evident amplified spontaneous emission between pulses, thus the pulse energy and peak power are 465 μJ and 2.36 kW, respectively.     

Ring-doped cladding-pumped single-mode three-level fiber laser

We propose and theoretically analyze three-level cladding-pumped fiber lasers in which the laser-active dopant is placed in a ring around a single-mode core. A ring-doped laser can work efficiently at wavelengths with strong small-signal absorption. This is otherwise difficult in a cladding-pumped fiber. Moreover, ring doping makes the laser less sensitive to quenching of the laser-active dopant and to excited-state absorption of the lasing field. In simulations of a Yb(3+) -doped fiber laser, ring doping increased the slope efficiency to 62%, up from 13% for a conventional core-doped fiber.     

Efficient skew-angle cladding-pumped tunable narrow-linewidth Yb-doped fiber laser

A skew-angle cladding-pumped tunable Yb-doped fiber laser is presented. The laser was tunable over more than 30 nm, from 1022 to 1055 nm, by employing a volume Bragg grating in a retroreflector configuration as one of the cavity delimiters. Output powers in excess of 4.3 W were recorded with a spectral bandwidth of 5 GHz and an M(2) value below 1.3 over the whole tuning range.     

Efficient single-mode operation of a standing-wave dye laser

The selection of a single longitudinal mode of a dye laser can be achieved with double or triple Michelson reflectors instead of Fabry-Perot etalons inside the laser cavity. These systems can be adapted to commercial multimode dye lasers. They provide a high efficiency and a good geometrical quality of the output beam. With a 7 watt pump power (λ=514.5 nm line of the Ar⁺ laser), a tunable output power of 1 watt was obtained at the peak of R6G, in the main output beam; the total single-mode power, including the auxiliary output beams, exceeded 1.4 watt. These results correspond to efficiencies of 14% and 20%, respectively (24% and 30% slope efficiencies). We discuss in the text why these efficiencies are comparable to those of ring lasers. In the infrared, with a 4.5 watt pump power (red lines of a Kr⁺ laser), 250 mW of single-mode output power in the main output beam was obtained at 780 nm with Oxazine 750.     

Self-polarized ytterbium-doped fiber laser

We demonstrate a linearly-polarized, ytterbium-doped fiber laser that uses an uncoated, undoped ceramic YAG plate as the output coupler, and the corresponding polarization extinction ratio of laser beam increases with incident pump power and then saturates at larger pump power. For comparison, the output coupler of the fiber laser is replaced by 10% reflectivity plane mirror, while the feature of the polarization of laser output is kept unchanged. The results show that the origin of the pump-dependent and self-started polarization is associated with the intensity-dependent nonlinear birefringence in the gain fiber.     

Dual-wavelength-switching operation based on optical bistability in pump-bypassed ytterbium-doped fiber laser

The bistable feature of residual pump in a pump-bypassed Yb-doped fiber laser offers the potential to pump Er/Yb co-doped fiber in a bifurcated cavity for the lasing of the 1537 nm line. The results of our proof-of-concept demonstration show that the oscillations at 1040 nm and 1537 nm are operated in the wavelength-switching mode, and this suggests that the combination of optical bistability in a pump-bypassed fiber laser cavity with a bifurcated cavity could be one simple and efficient method for switchable dual-wavelength operation. PACS 42.55.Wd; 42.65.Pc; 42.79.Ta     

High-power continuous-wave cladding-pumped Raman fiber laser

We demonstrate a high-power single-mode cladding-pumped Raman fiber laser. The Raman fiber laser consists of a 1.2 km long germanium-doped double-clad fiber in a linear cavity, which is spliced to a single-mode fiber. The laser is end pumped by a multimode erbium-ytterbium-doped fiber, which is coupled to the inner cladding of the Raman fiber. The embedded core was designed to be single mode at the Raman Stokes wavelength, and up to 10 W of power was obtained at 1660 nm from the single-mode fiber end. The laser has a slope efficiency of 67% and a threshold of 6.5 W.     

Novel approach for single-ended operation of a cladding-pumped fibre laser

We report on the periodic polarization of α-phase proton- exchanged LiNbO₃ planar waveguides down to 5 μm period lengths using structured electrodes and electrical fields. Unlike a majority of previous work, room-temperature electric field poling has been carried out after waveguide fabrication. Chemical etching of the large guiding surface has revealed homogeneous and high-quality domains with duty cycles close to 0.5. Moreover, it was verified by diffraction techniques and etching that the domain structure is preserved more than 2 μm along the thickness of the waveguide. The excellent optical performances of single-domain α-phase waveguides were not affected by the periodic poling.     

50-watt ytterbium-doped double-clad fiber laser

A ytterbium-doped double-clad fiber laser with more than 50-W output, near diffraction-limited is demonstrated in SIOM. The optical-to-optical efficiency is about 44% with respect to incident pump power and the slope efficiency is 69% against launched pump power.     

Polarization-maintaining amplification of phase modulated pulse employing ytterbium-doped single-mode fiber amplifier

Polarization-maintaining fiber amplifier using ytterbium-doped single-mode fiber (SMF) is proposed. A 45° Faraday rotator mirror (FRM) and a polarization independent fiber loop circulator (FLC) with polarization-maintaining fiber (PMF) pigtails are used to realize double-pass amplification and birefringence self-compensation. Arbitrary state of polarization (SOP) such as the linear polarization and elliptical polarization can be maintained. Polarization-maintaining amplification of phase modulated pulse with this amplifier is experimentally demonstrated while introducing little intensity modulation itself.     

Numerical analysis of injection-seeded ytterbium-doped fiber laser

In this paper, the gain characteristics of injection-seeded ytterbium-doped fiber laser were demonstrated. Comparing with the conventional single-pass and double-pass fiber amplifier, the injection-seeded ytterbium-doped fiber laser has many advantages: such as high gain or output power, simple structure. The amplified spontaneous emission (ASE) of this fiber laser also was discussed in detail.     

掺Yb3+双包层光纤激光器实验中的荧光分析

在研究掺Yb3+光纤激光器的实验中,发现伴生有可见区的荧光,用光谱仪测量发现该可见区荧光的波长分别为639.4 nm,520.7 nm,487 nm和474.8 nm,通过对比分析掺Yb3+光纤中杂质的能级结构,发现伴生的红、绿、蓝荧光由Yb3+与Pr3+合作产生,其荧光过程是由于Yb3+离子的能量转移给Pr3+,由Pr3+受激辐射产生的红、绿、蓝荧光.实验结果表明:掺Yb3+双包层光纤吸收泵浦光后产生的荧光是上转换的,这会导致光纤激光器激光能量转换效率的降低.     

All-fiber tunable ytterbium-doped double-clad fiber ring laser

We have designed and realized a cw all-fiber tunable Yb-doped double-clad fiber laser in a unidirectional ring cavity. The side-pumping V-groove technique is used, yielding very good launching efficiency of the high-power pumping laser diode, together with a compact configuration. The fiber laser delivers as much as 800 mW of power and is tunable in the spectral range 1.04-1.10 microm . The laser linewidth is ~0.1 nm .     

Dissipative soliton operation of an ytterbium-doped fiber laser mode locked with atomic multilayer graphene

Mode locking of an ytterbium-doped fiber laser with atomic multilayer graphene is, to the best of our knowledge, experimentally demonstrated for the first time. Dissipative solitons with duration of 580 ps at 1069.8 nm were generated. Since graphene can also be used to mode lock erbium-doped fiber lasers, our result shows that graphene indeed has wavelength-independent saturable absorption, which could be exploited to mode lock fiber lasers with various operating wavelengths.     

Diode-pumped 1018-nm ytterbium-doped double-clad fiber laser

We report a 1 018-nm ytterbium-doped double-clad fiber laser pumped by 970-nm diode. A pair of fiber Bragg gratings with reflectivities of 99.9% and 9% at a center wavelength of 1 018.9 nm are employed as cavity mirrors. The ytterbium-doped double-clad fiber is a 2.6-m-long Liekki fiber. Laser output power of 7.5 W at 1 018 nm is obtained under the pump power of 59.2 W. The overall slope efficiency of the fiber laser is about 16%. This low slope efficiency is mainly due to the incomplete absorption of the pump power.     

High-power, single-mode, linearly polarized, ytterbium-doped fiber superfluorescent source

High-power operation of a single-mode, linearly polarized, broadband superfluorescent fiber source has been achieved by using a two-stage cladding-pumped fiber configuration comprising a low power, single-ended, ytterbium-doped superfluorescent fiber seed source and a high-power cladding-pumped, polarization-maintaining, large-mode-area, ytterbium-doped amplifier pumped by a high-power diode source at 976 nm. The source yielded a maximum linearly polarized output of 106 W with a slope efficiency of up to 67% with respect to the launched pump power and with a measured polarization extinction ratio of 13.5 dB. The wavelength spectrum of the superfluorescent source spanned the range continuously from ~1035 to 1100 nm, and the bandwidth (FWHM) of the emission spectrum was 21 nm. The minimum seed power required for an output power over 100 W was only 10 mW, corresponding to an effective power gain in the amplifier stage of 40 dB. Single-spatial-mode operation with a beam propagation factor (M(2))<1.1 was achieved by bending the amplifier fiber to a bend radius of ~8 cm, without a significant reduction in output power.     

90-fs stretched-pulse ytterbium-doped double-clad fiber laser

We report ultrashort, high-energy pulse generation from a side-pumped Yb-doped double-clad fiber laser. The laser is operating in the stretched-pulse regime. It directly generates 4.8-ps, 5-nJ pulses that are extracavity compressed to 90 fs.     

Wavelength-selection erbium fiber laser with single-mode operation using simple ring design

In this demonstration, we propose and experimentally investigate a wavelength-selection erbium-doped fiber (EDF) laser in single-longitudinal-mode (SLM) by using simple fiber ring scheme design. We use a tunable bandpass filter (TBF) inside the gain cavity to restrict the lasing frequency. The proposed ring cavities can also serve as the mode filters for side mode suppression. Based on the simple ring cavity design, the mode hopping can be avoided to achieve SLM output. The TBF inside the laser scheme also obtains the wavelength tuning in the range of 1520.02 to 1562.02 nm. In addition, the output performance of the proposed fiber laser has also been discussed.     

Ultra-short pulsed ytterbium-doped fiber laser and amplifier

This paper investigates a high power all fiber ultrashort pulse laser system. This system consists of a modelocking laser oscillator, a multi-stage amplifier, a pulse selector, and a paired grating pulse compressor.With pulse energy of 12 μJ at repetition rate of 30 kHz, the laser at center wavelength of 1.05 μm was obtained. Pulse width of 525 fs was achieved after the grating pair compressor.     

High-energy, high-power ytterbium-doped Q-switched fiber laser

We report on a Q -switched, cladding-pumped, ytterbium-doped large-mode-area fiber laser operating at 1090 nm that is capable of generating 2.3 mJ of output pulse energy at a 500-Hz repetition rate and more than 5 W of average output power at higher repetition rates in a high-brightness beam (M(2) = 3) . Using a similar fiber with a smaller core, we generated >0.5-mJ pulses in a diffraction-limited beam. Our results represent a threefold increase in pulse energy over previously published values for Q-switched fiber lasers and firmly establish fiber lasers as compact, multiwatt, multimillijoule pulse sources with large scope for both industrial and scientific applications.