Q-Switched Ytterbium-Doped Fiber Laser Using Black Phosphorus as Saturable Absorber

We demonstrate a Q-switched ytterbium-doped fiber laser （YDFL） using a newly developed multi-layer black phosphorous （BP） saturable absorber （SA）. The BP SA is prepared by mechanically exfoliating a BP crystal and sticking the acquired BP flakes onto a scotch tape. A small piece of the tape is then placed between two ferrules and incorporated in a YDFL cavity to achieve a stable Q-switched operation in a 1.0 μm region. The laser has a pump threshold of 55.1 mW, a pulse repetition rate that is tunable from 8.2 to 32.9 kHz, and the narrowest pulse width of 10.8 μs. The highest pulse energy of 328 nJ is achieved at the pump power of 97.6 mW. Our results show that multi-layer BP is a promising SA for Q-switching laser operation.

A kW Continuous-Wave Ytterbium-Doped All-Fiber Laser Oscillator with Domestic Fiber Components and Gain Fiber

We demonstrate a kW continuous-wave ytterbium-doped all-fiber laser oscillator with M1 domestic fiber compo- nents： a 7× I fused fiber bundle combiner, a fiber Bragg grating and a double-clad gain fiber. The oscillator operates at 1079.48nrn with 80.94% slope efficiency and shows no limit of temperature and nonlinear effects. These indicate that the passive fiber components and the gain fiber are all qualified for the high power environ- ment. No evidence of the signal power roll-over shows that this oscillator possesses the capacity to higher output with available pump power.

Wavelength-Tunable Single Frequency Ytterbium-Doped Fiber Laser with Loop Mirror Filter

By using a loop mirror filter, a novel wavelength-tunable single-frequency ytterbium-doped fiber laser is developed to select single longitudinal modes in a linear cavity. The output wavelength could be tuned 2.4 nm intervals range from 1063.3 to 1065.Tnrn with the temperature change of the fiber Bragg grating. The maximum output power could reach 32 m W while the pump power increases to 120 m W. The corresponding optical-to-optical conversion efficiency is 26.7% and the slope efficiency is 33.9%, respectively. The output power fluctuation is below 2%, and its highest signal-to-noise ratio is 60 dB.

Optical properties of ytterbium-doped tandem-pumped fiber oscillator

With the rapid development of ytterbium-doped fiber lasers, some obtrusive limitations on power scaling appeared. In order to avoid these problems, a scheme called tandem pumping is introduced into the fiber laser field. In this paper, the optical properties of an ytterbium-doped tandem-pumped fiber oscillator are presented. According to the oscillator profile, the proper gain fiber type and pump wavelength range are picked out, under the comprehensive consideration of laser conversion efficiency and beam quality. In addition, the photodarkening performances of tandem pumping lasers and conventional ones are compared based on practical application, with all possible impact parameters taken into account. Moreover, an all-fibered tandem-pumped oscillator centered at 1079.5 nm is built, in the way of clad pumping by a 1030-nm fiber laser. The laser power of the oscillator reaches 7 W, with an opto-optic efficiency of 82.4%.

Dual-Wavelength Passively Q-Switched Ytterbium-Doped Fiber Laser Based on Aluminum Oxide Nanoparticle Saturable Absorbers

We report on generation of a dual-wavelength, all-fiber, passively Q-switched ytterbium-doped fiber laser using aluminum oxide nanoparticle （Al2O3-NP） thin film. A thin film of Al2O3 was prepared by embedding Al2O3-NPs into a polyvinyl alcohol （PVA） as a host polymer, and then inserted between two fiber ferrules to act as a saturable absorber （SA）. By incorporating the Al2O3-PVA SA into the laser cavity, a stable dual-wavelength pulse output centered at 1050 and 1060.7nm is observed at threshold pump power of 80mW. As the pump power is gradually increased from 80 to 300mW, the repetition rate of the generated pulse increases from 16.23 to 59 kHz, while the pulse width decreases from 19 to 6μs. To the best of our knowledge, this is the first demonstration for this type of SA operating in the 1 μm region.

Low-Threshold Broadband Spectrum Generation by Amplification of Cascaded Stimulated Raman Scattering in an Ytterbium-Doped Fiber Amplifier

We present an experimental study on low-threshold broadband spectrum generation mainly due to the amplirfication of the cascaded stimulated Raman scattering （SRS） effect in a four-stage fiber master oscillator power amplifier system. The cascaded SRS is achieved by using a long passive fiber pumped by a pulsed fiber laser cen： tered at wavelength 1064 nm. The amplified spontaneous emission during the amplification process is efficiently suppressed by cutting the length of the passive fiber and by using a double-clad ytterbium-doped fiber amplifier. The generated broadband spectrum spans from 960nm to 1700nm with maximum average output 13.6 W and average spectral power density approximately 17. 7 mW/nm.

Flattening Spectrum of a Broadband and Wavelength Stable Erbium Doped Superfluorescent Fiber Source

A technique is used to design the spectra in erbium doped superfluorescent fiber source experimentally and theoretically.In an erbium doped fiber with a 10m length and 300ppm concentration,a line width of about 42nm and high mean wavelength stability(<0.lppm/K,<0.2ppm/mW)were obtained by means of a suitable population distribution,and adjusting the ratio of backward to forward pump power.Also,its thermal characteristic is studied.These results will improve the performance of fiber optical gyroscope and fiber sensors,and will be applied in erbium doped fiber amplifier with flattening gain.

Stable and High OSNR Compound Linear-Cavity Single-Longitudinal-Mode Erbium-Doped Silica Fiber Laser Based on an Asymmetric Four-Cavity Structure

We propose a stable and high optical signal-to-noise ratio(OSNR)compound linear-cavity single-longitudinal-mode(SLM)erbium-doped silica fiber laser.It consists of three uniform fiber Bragg gratings(FBGs)and two fiber couplers to form a simple asymmetric four-cavity structure to select the longitudinal mode.The stable SLM operation at the wavelength of 1544.053 nm with a 3 dB bandwidth of 0.014 nm and an OSNR of~60 dB was verified experimentally.Under laboratory conditions,a power fluctuation performance of less than 0.05 dB for 5 h and wavelength variation of less than 0.01 nm for about 150 min is demonstrated.Finally,the characteristic of laser output power as a function of pump power is investigated.The proposed system provides a simple and cost-effective approach to realize a stable SLM fiber laser.

Optical Pulse Compression Based on High-doped Erbium Fiber Amplifier and Standard Single-mode Fiber

Proposed is a novel optical pulse compression technique based on high-doped erbium fiber amplifier and standard single-mode fiber(SMF). We used the amplifier with the erbium ion concentration of 6.3×10-3 to amplify a hyperbolic secant pulse from a regeneratively mode-locked fiber laser. The central wavelength, pulsewidth and peak power of the pulse are 1 550 nm, 12.5 ps and 3 mW, respectively. Then the amplified pulse with peak power level corresponding to a higher-order soliton is compressed when it propagates through a 3-km-long single-mode fiber. Studied are the compressed pulses under different pump powers and fiber lengths. The results show that it can get a narrower pulse, and solve the difficulty that pulses at low power can not be compressed directly in the fiber. And the construct is compact.

Stable single longitudinal mode erbium-doped silica fiber laser based on an asymmetric linear three-cavity structure

We present a stable linear-cavity single longitudinal mode （SLM） erbium-doped silica fiber laser. It consists of four fiber Bragg gratings （FBGs） directly written in a section of photosensitive erbium-doped fiber （EDF） to form an asymmetric three-cavity structure. The stable SLM operation at a wavelength of 1545.112 nm with a 3-dB bandwidth of 0.012 nm and an optical signal-to-noise ratio （OSNR） of about 60 dB is verified experimentally. Under laboratory conditions, the performance of a power fluctuation of less than 0.05 dB observed from the power meter for 6 h and a wavelength variation of less than 0.01 nm obtained from the optical spectrum analyzer （OSA） for about 1.5 h are demonstrated. The gain fiber length is no longer limited to only several centimeters for SLM operation because of the excellent mode-selecting ability of the asymmetric three-cavity structure. The proposed scheme provides a simple and cost-effective approach to realizing a stable SLM fiber laser.

Experimental investigation on chaos generation in erbium-doped fiber single-ring lasers

In this paper,the chaotic behaviors in an erbium-doped fiber（EDF） single-ring laser（EDFSRL） are investigated experimentally by using the loss modulation method.An electro-optic modulator（EOM） made of LiNbO 3 crystal is added to the system.Thus,by changing the modulation voltage and the modulation frequency of the EOM,the freedom of the EDFSRL system is increased.The chaotic characteristics of the system are studied by observing the time series and the power spectra.The experimental results indicate that the erbium-doped fiber single-ring laser system can enter into chaos states through period-doubling bifurcation and intermittency routes.

Performance Comparison of Mode-Locked Erbium-Doped Fiber Laser with Nonlinear Polarization Rotation and Saturable Absorber Approaches

A mode-locked erbium-doped fiber laser (EDFL) is demonstrated using a highly concentrated erbium-doped fiber (EDF) as the gain medium in a ring configuration with and without a saturable absorber (SA).Without the SA,the proposed laser generates soliton pulses with a repetition rate of 12 MHz,pulse width of 1.11 ps and energy pulse of 1.6pJ.By incorporating SA in the ring cavity,the optical output of the laser changes from soliton to stretched pulses due to the slight change in the group velocity dispersion.With the SA,a cleaner pulse is obtained with a repetition rate of 11.3 MHz,a pulse width of 0.58ps and a pulse energy of 2.3pJ.

A novel 3-stage structure for a low-noise, high-gain and gain-flattened L-band erbium doped fiber amplifier

The configuration of the novel three-stage L-band erbium-doped fiber amplifier with very large and flat gain and very low noise figure presented in this paper uses the forward ASE (amplified spontaneous emission) from the first section of the EDF (erbium-doped fiber) and the backward ASE from the third section of the EDF (both serve as the secondary pump sources of energy) to pump the second EDF. To improve the pump efficiency, the power of the pump is split into two parts (with a ratio of e.g. 2:7). The characteristics of this L-band EDFA are studied on the basis of the Giles Model with ASE.

Erbium Doped Fiber Laser and Amplifier

In this paper, new configuration is proposed, investigated and analyzed. Fiber laser and fiber amplifier are merged in one configuration which called Erbium Doped Fiber Laser and Amplifier (EDFLA) or integrating EDFL and EDFA in one design. The configuration has three main outputs;one for laser, second for amplifier and the third it can be used for on/off output. A surprising phenomenon was remarked during the operation of this configuration. The amplification is abolished during the lasing state and appeared again if the lasing is stopped or the switch is off. The difference between outputs with the lasing and without lasing has 30 dB EDFA gain value;it is a good sign that this optical configuration can be used as an on/off integrated optical device for fiber laser.

Analysis of New Q-switched Erbium Doped Fiber Laser Based on Fiber Grating Loop Mirror

An all fiber wavelength selective Q switching modulator based on fiber grating loop mirror is proposed. A newly configured Q switched erbium doped fiber laser using this all fiber modulator is numerically analyzed taking into account the effects of the spontaneous emission.

Bidirectional Erbium Doped Fiber Amplifiers

Bidirectional EDFAs(Bi-EDFAs)featuring bidirectional signal input are theoreticallystudied.Gain and noise performances of Bi-EDFAs are analysed numerically and comparedwith that of other optical amplifiers.Applications of Bi-EDFAs in fiber networks and otherfields are considered.

2×3 kW bidirectional output fiber oscillator employing spindle-shaped ytterbium-doped fiber

A 2×3 kW-level bidirectional output fiber oscillator is realized by combining the specially designed spindle-shaped ytterbium-doped fiber,non-wavelength-stabilized 976-nm LDs,and grating bandwidth optimization to balance transverse mode instability and stimulated Raman scattering.The maximum output powers at both ends are 3265 and 2840 W,respectively,with a total efficiency of 73.2%.The M^(2) factors of the lasers at both ends are about 1.98 and 2.38,respectively.The beam profile at both ends shows that a bidirectional output annular beam fiber oscillator has been realized,which has great potential in practical applications.

Modeling and Experiments of the Gain and Noise Figure for an Irradiated Erbium-Ytterbium Co-Doped Fiber Amplifier

It is crucial to study the effect of radiation on the fiber amplifier devices. In the present paper, the Erbium-ytterbium co-doped fiber amplifier (EYDFA) has been irradiated by a neutron beam of different doses for various exposure times from an Am-241/Be-9 neutron source. The gain and noise figure of the EYDFA have been calculated theoretically and recorded after and before the irradiation to test its performance under the effect of irradiation. In order to show the enhancement in the gain of the fiber amplifier devices, a comparison between the gain of the irradiated EYDFA and Erbium doped Fiber amplifier (EDFA) has been carried out. The calculated results by the proposed model are in good agreement with the experimental ones. It indicates that the gain of EYDFA deteriorates after being irradiated by a neutron dose. Moreover, the gain of irradiated EYDFA has been reduced to 13.8 dB at a dose of 720 Gy.

Passively Q-Switched Erbium-Doped Fiber Laser Based on GeSe Saturable Absorber

GeSe nanosheets were prepared by ultrasonic-assisted liquid phase exfoliation (LPE), and the nonlinear saturated absorption performance was experimentally studied. The modulation depth and saturation intensity of the prepared GeSe saturable absorber (SA) were 15% and 1.44 MW/cm2, respectively. Using the saturated absorption characteristics of GeSe SA, a passively Q-switched erbium-doped fiber laser was systematically demonstrated. As the pump power increases, the pulse repetition frequency increases from 22.8 kHz to 77.59 kHz. The shortest pulse duration is 1.51 μs, and the corresponding pulse energy is 46.14 nJ. Experimental results show that GeSe nanosheets can be used as high-efficiency SA in fiber lasers. Our results will provide a useful reference for demonstrating pulsed fiber lasers based on GeSe equipment.

Passively Q-Switched Erbium-Doped Fiber Laser with TiSe₂as Saturable Absorber

The TiSe2 nanosheets were prepared by means of ultrasound-assisted liquid phase exfoliation (LPE) and the nonlinear saturable absorption properties were experimentally investigated. The modulation depth, saturation intensity and nonsaturable absorbance of the prepared 1T-TiSe2 SA were 15.7%, 1.28 MW/cm2 and 8.2%, respectively. Taking advantage of the saturable absorption properties of TiSe2-based SA, a passively Q-switched erbium-doped fiber (EDF) laser was systematically demonstrated. The pulse repetition rates varied from 24.50 kHz up to 73.79 kHz with the increasing pump power. The obtained shortest pulse width was 1.31 μs with pulse energy of 79.28 nJ. The system presented merits of low-cost SA preparation, system compactness, superb stability and high competition.