Erbium-doped All-fiber Ring Laser Research Articles

Harmonic mode-locked noise-like pulses under a Q-switched envelope in an erbium doped all-fiber ring laser.

We report for the first time, to the best of our knowledge, harmonic mode-locked noise-like pulses under a Q-switched envelope in an all-fiber erbium doped ring laser cavity, mode locked using the nonlinear polarization rotation (NPR) technique. For a cavity with a fundamental repetition rate of 1.33 MHz, stable mode-locked noise-like pulses, with few nanoseconds durations, single pulse energies around 30-40 nJ, and Q-switched repetition rates up to 31 kHz, were produced and characterized from the fundamental to the eighth harmonic. The formation and evolution of Q-switched harmonic mode-locked noise-like pulses were preceded by the formation of Q-switched mode-locked noise-like pulse bunches. This is also the first report on noise-like bunches under a Q-switched envelope, to our knowledge. Our studies also provide further insights into the interplay of different physical mechanisms involved in the production of such ultrashort pulses. Such sources should prove especially useful for efficient supercontinuum generation and laser micromachining.

Simulation of ultrashort pulse generation in an all-fiber erbium-doped ring laser with a highly nonlinear cavity

The generation of ultrashort pulses in an all-fiber erbium ring laser with a highly nonlinear cavity is mathematically modeled. It is shown that ultrashort pulses with the characteristics of both stretched pulses and solitons are generated in a highly nonlinear fiber cavity. The evolution of the width, energy, and spectral width of the ultrashort pulses in the fiber laser is obtained in the mathematical analysis. It is shown that an ultrashort pulse in a highly nonlinear cavity has a minimum width of about 200 fs, a maximum spectral width at half-height of about 17 nm, and a maximum energy of about 180 pJ. The modeling results are verified by comparing them with experimental data.

Multibound Soliton Formation in an Erbium-Doped Ring Laser With a Highly Nonlinear Resonator

We have studied the generation of low-noise ultrashort multibound solitons in the telecommunication spectral window in an erbium-doped all-fiber ring laser with a highly-nonlinear resonator mode-locked by a nonlinear polarization evolution effect. The multibound soliton generation is obtained with more than 20 bound dechirped pulses with a duration of ~ 240 fs at a repetition rate of ~ 11.3 MHz (with a signal-to-noise ratio of ~ 73.3 dB), the relative intensity noise is $\sim 1.3\cdot 10^{\mathbf {-8}}$ with a time averaging window of ~ 100 s.

High-energy ultrashort-pulse all-fiber erbium-doped ring laser with improved free-running performance

We report on stable stretched-pulse generation with a pulse duration (at FWHM) ∼180 fs at a central wavelength of 1560 nm with an average output power of 30 mW at a repetition rate of ∼11.3 MHz (with the signal-to-noise ratio at a fundamental frequency ∼59 dB) with an Allan deviation of a pulse repetition frequency of ∼5.75·10−9 for a 1 s interval and a relative intensity noise of <−101 dBc/Hz<−101 dBc/Hz (30–1000 kHz). This corresponds to a <14.7 kW maximum peak power and a <2.6 nJ maximum available pulse energy obtained immediately from the highly nonlinear all-fiber laser resonator.

Comb Peculiarities of Dispersion-Managed Solitons in a Hybrid Mode-Locked All-Fiber Ring Laser

We studied the optical comb peculiarities of the ultra-short dispersion-managed soliton generation in an erbium-doped all-fiber ring laser hybrid mode-locked with carbon:boron nitride single-walled nanotubes in the co-action with a nonlinear polarization evolution. A stable low-intensity-noise optical comb was obtained with a narrow single comb linewidth of 18.1 kHz based on dechirped 90-fs pulses with a repetition rate of 42.22 MHz, a spectral pulse width of 56 nm, and an average output power of 16.7 mW corresponding to 4.4-kW maximum peak power and 0.4-nJ pulse energy.

Generation regimes of bidirectional hybridly mode-locked ultrashort pulse erbium-doped all-fiber ring laser with a distributed polarizer.

We report on the stable picosecond and femtosecond pulse generation from the bidirectional erbium-doped all-fiber ring laser hybridly mode-locked with a coaction of a single-walled carbon nanotube-based saturable absorber and nonlinear polarization evolution that was introduced through the insertion of the short-segment polarizing fiber. Depending on the total intracavity dispersion value, the laser emits conservative solitons, transform-limited Gaussian pulses, or highly chirped stretched pulses with almost 20 nm wide parabolic spectrum in both clockwise (CW) and counterclockwise (CCW) directions of the ring. Owing to the polarizing action in the cavity, we have demonstrated for the first time, to the best of our knowledge, an efficient tuning of soliton pulse characteristics for both CW and CCW channels via an appropriate polarization control. We believe that the bidirectional laser presented may be highly promising for gyroscopic and other dual-channel applications.

High-energy, sub-100 fs, all-fiber stretched-pulse mode-locked Er-doped ring laser with a highly-nonlinear resonator.

We report on ultra-short stretched pulse generation in an all-fiber erbium-doped ring laser with a highly-nonlinear germanosilicate fiber inside the resonator with a slightly positive net-cavity group velocity dispersion (GVD). Stable 84 fs pulses were obtained with a 12 MHz repetition rate at a central wavelength of 1560 nm with a 48.1 nm spectral pulse width (full width at half maximum, FWHM) and 30 mW average output power; this corresponds to the 29.7 kW maximum peak power and 2.5 nJ pulse energy obtained immediately from the oscillator.

Ultra-short pulse generation in the hybridly mode-locked erbium-doped all-fiber ring laser with a distributed polarizer

We report for the first time to the best of our knowledge on the ultra-short pulse (USP) generation in the dispersion-managed erbium-doped all-fiber ring laser hybridly mode-locked with boron nitride-doped single-walled carbon nanotubes in the co-action with a nonlinear polarization evolution in the ring cavity with a distributed polarizer. Stable 92.6 fs dechirped pulses were obtained via precise polarization state adjustment at a central wavelength of 1560 nm with 11.2 mW average output power, corresponding to the 2.9 kW maximum peak power. We have also observed the laser switching from a USP generation regime to a chirped pulse one with a corresponding pulse-width of 7.1 ps at the same intracavity dispersion.

Hybrid mode-locked erbium-doped all-fiber soliton laser with a distributed polarizer.

A soliton-type erbium-doped all-fiber ring laser hybrid mode-locked with a co-action of arc-discharge single-walled carbon nanotubes (SWCNTs) and nonlinear polarization evolution (NPE) is demonstrated. For the first time, to the best of our knowledge, boron nitride-doped SWCNTs were used as a saturable absorber for passive mode-locking initiation. Moreover, the NPE was introduced through the implementation of the short-segment polarizing fiber. Owing to the NPE action in the laser cavity, significant pulse length shortening as well as pulse stability improvement were observed as compared with a SWCNTs-only mode-locked laser. The shortest achieved pulse width of near transform-limited solitons was 222 fs at the output average power of 9.1 mW and 45.5 MHz repetition frequency, corresponding to the 0.17 nJ pulse energy.

Long-cavity all-fiber ring laser actively mode locked with an in-fiber bandpass acousto-optic modulator

We demonstrate low-frequency active mode locking of an erbium-doped all-fiber ring laser. As the mode locker, we used a new in-fiber bandpass acousto-optic modulator showing 74% modulation depth, 3.7 dB power insertion losses, 4.5 nm of optical bandwidth, and 20 dB of nonresonant light suppression. The laser generates 330 ps mode-locked pulses over a 10 ns pedestal, at a 1.538 MHz frequency, with 130 mW of pump power.

S-band pulse generation by polarization additive-pulse mode-locking in an erbium-doped all-fiber ring laser

An all-fiber S-band mode-locked Er-doped fiber ring laser operated at 1503 nm is experimentally demonstrated by utilizing the polarization additive-pulse mode-locking (P-APM) mechanism. To the best of our knowledge, it is the first P-APM mode-locked fiber laser operating in the S-band. The gain medium is an S-band Er-doped fiber amplifier (EDFA) composed of two Er-doped fiber stages with the technique of depressed-cladding to cut off the fundamental mode. Stable single-pulse operation is achieved within the available pump power range. Besides, characterization of the S-band EDFA module, such as the wavelength dependences of the gain and noise figure, the slope efficiency, as well as the dependence of the pump power on the gain for different input powers is performed. In addition, analysis of the proposed S-band mode-locked fiber laser, such as the pump power dependence of the pulse-width and optical bandwidth, and pulse-width compression is also provided.

Switchable dual-wavelength passively Q-switched erbium-doped fiber ring laser using nonlinear polarization rotation technique

We experimentally demonstrate a switchable dual-wavelength passively Q-switched pulsed operation in an Erbium-doped all-fiber ring laser utilizing the nonlinear polarization rotation technique.At a low pump power of 25 mW, Q-switched pulse train possessing a temporal repetition rate of 12.7 kHz as well as a pulse width of 8.4 μs is generated stably with dual wavelengths centered at 1569.92 nm and 1587.28 nm. In addition, the switching operation between the two wavelengths can be facilely implemented by carefully adjusting the polarization controllers. Self-mode-locking effect is also observed and discussed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1000–1003, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25930

Widely ultra-narrow linewidth 104 nm tunable all-fiber compact erbium-doped ring laser

A widely tunable narrow linewidth compact erbium-doped all-fiber ring laser with 104 nm tuning range was reported. An all-fiber Fabry-Perot filter (FFP-TF) was used to realize the laser tuning output, and the wavelength at constant voltage had high time stability. With the 8 m length erbium-doped fiber as gain medium, we realized widely tunable laser from 1513 to 1617 nm with the linewidth less than 40 pm at any wavelength. Pumped by the 976 nm laser diode, the fiber laser worked with slope efficiency of above 10% and threshold of less than 21 mW.

55-fs pulse generation without wave-breaking from an all-fiber Erbium-doped ring laser

We demonstrate the direct generation of 55 fs pulses from an all-fiber Erbium-doped ring laser oscillator using the nonlinear polarization rotation mode-locking. The average output power is 56.4 mW but limited by available pump power of 330 mW. The linear chirped pulse duration is 55 fs after recompression using standard single-mode fiber. The pulses show to resist optical wave breaking with a smooth spectrum without any side lobe and cw-breakthrough. This all-fiber laser exhibits relatively high transfer efficiency of 17% and the single pulse energy reaches 1.5 nJ.