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We investigated a power dependent laser linewidth broadening effect in a sub-kHz single-longitudinal mode Er-doped fiber ring laser using an intra-cavity unpumped Erbium doped fiber loop.

High-repetition-rate fiber laser has widely applications in the field of femtosecond frequency comb, ultra-fast optical sampling, and so on. In this paper, an Er-doped femtosecond fiber laser with a repetition rate of 303 MHz is demonstrated based on the mechanism of nonlinear polarization rotation. By means of optimization of cavity dispersion, the net dispersion in fiber cavity is a little negative nearby zero point. After mode locking, the laser is operating in the stretched-pulse regime. At a pump power of 817 mW, the output power of the laser is 125 mW in continue-wave state, and 69 mW in mode-locking state. The laser directly generates 90 fs before dispersion compensation. Mode locking can self-start at the pump power of 700-817 mW. Repetition rate drift of the mode-locked laser is 30 Hz in five hours.

International audience; We report the experimental generation of alternate multiwavelength pulse trains in a mode-locked fiber ring laser containing an unbalanced Mach-Zehnder interferometer at an aggregate repetition rate of 18.8 GHz. These results are compared with simulations

The frequency of a 1.54-/spl mu/m erbium fiber laser was stabilized to a /sup 13/C/sub 2/H/sub 2/ absorption line by employing a new feedback system with a LiNbO/sub 3/ frequency modulator and a double-balanced-mixer. The stability reached as high as 2.2 /spl times/ 10/sup -11/ for /spl tau/=100 s.

A multiwavelength fiber ring-laser employing a pair of silica-based arrayed-waveguide-gratings (AWGs) is proposed to easily implement a stable multiwavelength operation for a variety of research needs. A fixed multiwavelength operation is available when the free-spectral-range (FSR) of the AWGs is wide enough to cover the gain bandwidth of deployed erbium-doped fiber amplifiers (EDFAs). A tunable multiwavelength operation is also available when the FSR is narrower than the gain bandwidth. 15 channels with 1.6-nm spacing in the fix type, and five channels with about 40-nm discretely tunable range at 1.4-nm spacing in the tunable type and almost 50-dB signal to amplified spontaneous emission (ASE) ratio in both types are demonstrated.

A novel wavelength-switchable fiber ring laser with output selectable from one of 35 different wavelengths is reported. Wavelength variation of /spl sim/5 pm and power fluctuation of /spl sim/0.12 dB, were observed during a 2-hour stability test.

We discuss basic concepts of the frequency-shifted feedback (FSF) laser and of our approach to modeling the physics of this device. Such apparatus offers potential for measuring incremental heights of surfaces with micrometer accuracy over meter or kilometer distances. We present experimental results, obtained using a Yb 3+ fiber ring laser, that demonstrate the usefulness of such a device.

Ultra-short optical pulse sources are key components in optical time-division multiplexing(OTDM) system. In this paper, a wavelength and repetition frequency tunable actively mode-locked fiber ring laser based on cross-gain modulation in a Reflective Semiconductor Optical Amplifier(RSOA) is demonstrated. Theoretical model for this scheme is also established and output characteristics are calculated. Stable picosecond pulse trains at 10-80 GHz repetition frequency are obtained. 30nm wavelength tuning range is achieved in our proposed actively mode-locked laser.

We demonstrate a photonic technique for the tunable generation of RF, microwave and millimeter wave signals with a single optical source. A dual-polarization supporting and maintaining fiber ring laser is constructed and its use as a tunable RF source is demonstrated.

We demonstrate all-photonic code conversion for OCDMA network applications based on cross-gain modulation in a semiconductor fiber ring laser. The code converter translates weight four spectral sequences and is capable of providing 2R regeneration.

We report a stabilization scheme of a FM mode-locked erbium fiber ring laser in anomalous dispersion or normal dispersion. Fast gain saturation characteristic of a SOA enabled supermode noise suppression up to 70 dB at both dispersion medium. (2 pages)

We present an experimental study of the self-starting probabilistic behavior of passively mode-locked lasers.

A dual-wavelength passively mode-locked-fiber laser is proposed and demonstrated The laser has a figure-of-eight structure with a nonlinear amplifying loop mirror for passive mode locking. Being different from active mode locking where the round-trip frequencies should be identical for all the wavelengths, the passively mode-locked-fiber ring lasers can achieve passive mode locking with different round-trip frequencies. Experimental results show that passive mode locking is realized at two wavelengths with different round trip frequencies at 762 kHz and 830 kHz.

Tunable all-optical wavelength converters have been regarded as key optoelectronic devices in intelligent next generation optical networks. Novel scheme for tunable wavelength conversion based on semiconductor optical amplifier (SOA)-based fiber ring laser is proposed out firstly. Theoretical model for this novel scheme is established. Conversion output characteristics are calculated theoretically and measured experimentally in different conditions. Experimental results are coincidence with theoretical results. Tunable wavelength conversion at 2.5Gb/s with 40nm tuning range is demonstrated experimentally. Experimental and theoretical studies show that this novel scheme is worthy of further investigation.

Bound states of twin-pulse solitons were experimentally observed in a passively mode-locked fiber ring laser. Similar to those of single-pulse solitons, the bound states of twin-pulse solitons are marginally stable and occur at some fixed, quantized soliton separations. Our experimental investigations revealed that the formation of such bound states might be resulted from the dispersive wave mediated long-range soliton interaction in the laser.

Summary form only given. In this paper we report the demonstration of a simple, totally fiber-pigtailed, actively mode-locked laser source, generating 10 simultaneously synchronized wavelength channels, each at 10 GHz, producing as short as 21 ps pulses. The laser ring cavity is composed entirely of fiber-pigtailed devices. Gain is provided by a 500 /spl mu/m, bulk InGaAsP/InP ridge waveguide SOA with 10/spl deg/ angled and antireflection coated facets. The device has a small signal gain of 23 dB when driven with a 250 mA dc current at 1535 nm.

Four states of bound-soliton operation in a passively mode-locked fiber ring laser have been revealed. Detailed studies on their properties show that they are not just binding states of single-pulse solitons, but rather a novel form of solitary waves in the laser, twin-pulse (-hump) temporal solitons. We demonstrated both experimentally and numerically that, like the single-pulse soliton operation, the twin-pulse soliton emission is another intrinsic feature of the laser.

We study the dependence of timing and energy jitter of an actively mode-locked dispersion-managed fiber ring laser on the strength of the dispersion management and on the location of the amplifier in the cavity.

A 2.5 ps pulse width, 40 GHz repetition rate, 20 nm tuning range, mode-locked fiber ring laser is presented. The source mode-locks through gain saturation of its SOA from an external 5 GHz DFB diode.

Absence of relaxation oscillation in SOA fiber ring lasers is analyzed in this paper, which is always presented in actively mode- locked erbium-doped fiber (EDF) ring lasers. The super-mode competition can be effectively suppressed in SOA ring lasers due to the gain saturation of SOA. The experimental demonstrations were confirmed the above issues and good stability in a SOA mode-locked fiber ring laser without any feedback circuits was shown.

Dark soliton formation and soliton dynamics in all-normal dispersion cavity fiber ring lasers without an anti-saturable absorber in cavity is studied both theoretically and numerically. It is shown that under suitable conditions the dark solitons formed could be described by the nonlinear Schrödinger equation. The dark soliton formation in an all-normal-dispersion cavity erbium-doped fiber ring laser without an anti-saturable absorber in cavity is first experimentally demonstrated. Individual dark solitons are experimentally identified. Excellent agreement between theory and experiment is observed.

We demonstrate bright?dark pulses near 2 ?m in a Tm-doped fiber laser (TDFL) for the first time. Bright?dark pulses could be achieved when the laser works in the passively mode-locking regime and the net group velocity dispersion is quite anomalous. A polarization controller is employed to manipulate the polarization states of the laser oscillation modes. The dark and bright pulses are confirmed to be two orthogonal linear polarization components that are coupled incoherently in the laser cavity. Experimental results also show that the dark and bright pulses have different spectral distributions.

The self-injection locking single frequency Yb-doped fiber ring laser is reported. The system shows compact, stable and tunable. In the primary experiment, the Self-injection locking single frequency fiber ring laser with wavelength 1.05325)mum, power exceeding 3.5mW,line-width less than 36 MHz was manufactured. The laser shows stability, low threshold and high power. No mode-hopping was observed within 2 hours. The single polarization output can be obtained when use single polarization fiber.

A multiwavelength Ytterbium-doped fiber ring laser operating at 1030 nm region is demonstrated using a Sagnac loop mirror. The Ytterbium-doped fiber used is drawn from Yb2O3-doped perform, which is fabricated through deposition process in conjunc- tion with a solution doping technique. The loop mirror is constructed using a 3dB coupler and a piece of polarization maintaining fiber (PMF). The fiber laser generates a multiwavelength oscillation with up to five lines by adjusting both polarization controllers in the ring cavity. The line spacing is obtained at 2.1 nm, which is strongly de- pendent on the PMF's length used. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2511-2512, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop. 24605

Erbium-doped fibers are making it possible to develop compact, diode-pumped sources of ultrashort pulses for a variety of applications. Operating principles of these devices are reviewed and recent experimental progress in our laboratory on soliton and stretched-pulse lasers is described.

Theoretical and experimental results on the self-starting passive mode-locked Yb fiber-ring laser generating short pulse are reported. The relations between the laser-cavity parameters and mode-locked pulse characteristics are discussed. 980-nm LD-pumped laser is used as the pump source and high-concentration Yb 3 + -doped fiber is adopted as the gain medium. Using the nonlinear polarization rotation (NPR) effect of the fiber, a self-starting stable mode-locked pulse is obtained, with a center wavelength of 1046 nm, a 3-dB bandwidth of 6.01 nm, and a 20-dB bandwidth of 16 nm. The mode-locked threshold power is 150 mW and output power is 26 mW with a 20-MHz repetition rate.

A Faraday rotator is installed in a laser cavity to eliminate spatial hole burning in an bidirectional Er-doped fiber ring laser. A beat signal between the clockwise and the counter-clockwise laser outputs of 40 dB above noise and of 25-30% fringe visibility was observed.

We demonstrate a novel mode locked ultrafast laser, based on an integrated high-Q microring resonator. Our scheme exhibits stable operation of two slightly shifted spectral optical comb replicas. It generates a highly monochromatic radiofrequency modulation of 65.8MHz with a linewidth < 10kHz, on a 200GHz output pulse train.

We analyse the generation of continuous-wave soliton train in an erbium-doped fiber ring laser by means of self-induced modulational instability.

We proposed and demonstrated a room-temperature multiwavelength ytterbium-doped fiber ring laser with fine adjustability and coarse tunability based on nonlinear polarization rotation effect. Stable five-lasing-wavelengths with spacing of 5.0 nm and four-wavelengths with spacing of 6.0 nm are obtained. The simultaneously lasing multiwavelengths can be finely adjusted within small as well as relatively large wavelength range.

Multiple-soliton dynamic patterns have been observed experimentally in an erbium-doped fiber ring laser with graphene as a saturable absorber. Under relatively low pumping power we have obtained disordered multiple-solitons, bunched solitons and high order harmonic mode locking by adjusting the orientation of the polarization controllers. With increased pumping power, we have also observed flow of solitons. We have experimentally investigated in detail the conditions under which these patterns form.

This is the first report on tunable fiber ring lasers whose wavelengths were widely controlled from 1285 to 1367 nm by changing the frequencies of the acoustic shear waves in acousto-optic (AO) filters. In this tuning range, a very narrow spectral linewidth of 15 kHz was observed.

In the present letter, the authors report on the realization of all-optical format conversion by using the cascaded sum- and difference-frequency generation in a periodically poled lithium niobate waveguide and the active mode locking in a reflective-semiconductor-optical-amplifier-based fiber ring laser. Tunable format conversions from nonreturn-to-zero pseudorandom binary sequence (PRBS) signal to return-to-zero PRBS idler at 10 and 20Gbit∕s are observed in the experiment.

Ultra-short optical pulse source is one of key components in optical time-division multiplexing(OTDM) system. In this paper, a wavelength and repetition rato tunable actively mode-locked fiber ring laser based on cross-gain modulation in a reflective Semiconductor Optical Amplifier(SOA) is demonstrated. Theoretical model for this scheme is also established and output characteristics are calculated. Stable picosecond pulse trains with high extinction ratio at 10—40 GHz repetition rato are obtained. 30nm wavelength tuning range is also achieved in our proposed actively mode-locked laser.

Due to a production error in the above-named paper [ibid., vol. 17, no. 9, pp. 1821?1823, Sep. 2005], Fig. 4 was printed twice. The correct Figs. 3 and 4 are provided.

In this paper, we proposed and demonstrated all-optical clock recovery at 10GHz with switchable wavelengths. Very stable clock signals corresponding to the bit rate of the injection data have been obtained by injecting 10Gbit/s 231-1 PRBS data signals into the ring cavity. Wavelength switching among eight wavelengths is achieved by merely tuning the delay time of the intra-cavity optical delay line. The proposed clock recovery method is experimentally demonstrated to be insensitive to the polarization changes of the input data.

We present a comprehensive broad-band model of tunable wavelength converter based on four-wave mixing (FWM) in semiconductor fiber ring laser (SFRL). Critical factors, e.g., the material gain profile, the longitudinal variation of the optical field, the carrier density and the broad-band spontaneous noise emission are considered in the model. By numerical simulation, the effects of the input signal power, injection current, the coupling of the output coupler and the lasing wavelength on the performance of the wavelength converter, such as the conversion efficiency and the SBR, are investigated. Numerical results are in agreement with the experimental results in literatures.

The effects of dispersion on the pulsewidth of a mode‐locked fiber ring laser are examined. We have identified two different modes of operation, one where the pulsewidth is determined by the path‐integrated (global) dispersion of the cavity and another novel mode where pulsewidth is not limited by the global dispersion. Experimental results show that for some configurations, the local dispersion of the cavity plays an important role in determining the pulsewidth of the laser.

Output characteristics of a tunable fiber ring laser are studied both by theoretical modeling and by experimentation. Dependencies of laser output power on lasing wavelength, pump power, erbiumdoped fiber (EDF) length, output coupling ratio, and intracavity loss are demonstrated by using a simple theoretical model. It is shown that a wide tunable range over 130nm (i.e.1500—1630nm) can be obtained through parameter optimization. As a result, the laser with a tunable range up to 100nm, high output power, and high signaltonoise ratio in most of the tunable range has been achieved in experimentation. The experimental data are in good agreement with the theoretical modeling results.