Mode-locked Erbium Fiber Ring Laser Research Articles

Transient response of a passively mode-locked Er-doped fiber ring laser

In this study, we report on the transient response of a passively mode-locked erbium fiber ring laser as studied by switching the optical pumping of the erbium doped fiber on and off. We confirm that the laser can maintain its mode-locking state even while the pump is modulated, and describe the laser behavior and its typical transient response upon abrupt changes in the intensity of the optical pump.

Four-wave mixing assisted self-stable 4×10 GHz actively mode-locked Erbium fiber ring laser

We proposed and developed a self-stable multiwavelength (4 cbannels) 10-GHz actively mode-locked Erbium-doped fiber ring laser with 0.8 nm wavelength spacing. A 1-km highly nonlinear fiber is incorporated in the laser cavity to eliminate the strong gain competitions in the homogeneously broadened EDF by multiple parametric four-wave mixing processes. The fiber nonlinearity is also helpful to provide phase locking and stabilize the output pulse. Stable laser pulses at 1556.55, 1557.36, 1558.17, and 1558.98 nm are successfully obtained simultaneously with supermode noise suppression ratio greater than 50 dB. The corresponding time-bandwidth products of four channels are 0.39 ~ 0.41.

Pulse stabilisation in harmonically FM modelocked erbium fibre ring laser with DFBLD

A new pulse stabilisation scheme for a harmonically frequency modulated (FM) modelocked erbium fibre ring laser using a distributed feedback laser diode (DFBLD) is presented. More than 65 dB supermode noise suppression in the RF spectrum was obtained with the proposed method. Effective reduction of supermode noise can be accomplished as the DFBLD in the fibre laser acts not only as a fast-gain saturated medium but also as an optical bandpass filter for suppressing supermode noise in a harmonically modelocked laser system.

Wavelength‐tunable actively mode‐locked fiber‐ring laser using an F‐P LD as a modulator and a tunable comb filter

AbstractA wavelength‐tunable actively mode‐locked erbium fiber ring laser is demonstrated using an F–P semiconductor as a modulator and a tunable comb filler. Continuous wavelength tuning is enlarged to 6 nm by successively choosing different cavity modes of the F–P LD and tuning the temperature of the LD. The ∼2‐GHz frequency pulse is generated with a side‐mode suppression ratio over 30 dB in the entire tuning range. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 318–320, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10753

Self-stabilized passive, harmonically mode-locked stretched-pulse erbium fiber ring laser

We have studied a passive, harmonically mode-locked stretched-pulse erbium fiber ring laser with net positive dispersion that is self-stabilized by gain depletion and electrostriction. Periodic pulses with supermode suppression of >75 dB and picosecond jitter are achieved. The pulses are compressible to 125 fs by external chirp compensation. The repetition rate is 220 MHz, and the average power is as high as 80 mW.

40 GHz actively modelocked polarisation-maintaining erbium fibre ring laser

The first polarisation-maintaining actively modelocked erbium fibre ring laser (ML-EFRL) operating at a base rate of 40 GHz is presented. The laser generates highly stable and virtually transform-limited 1.2–1.9 ps pulses tunable over 40 nm with a timing jitter of < 0.1 ps. These represent the shortest pulses and lowest timing jitter generated by a 40 GHz ML-EFRL.

Pulse chirp control in an actively modelocked fibre laser using a dual-drive variable-chirp modulator

It has been experimentally demonstrated that the chirp imposed on the pulses from an actively modelocked erbium fibre ring laser can be controlled by using a dual-drive variable-chirp modulator as a modelocker.

Wavelength-tunable actively mode-locked erbium-doped fiber ring laser using a distributed feedback semiconductor laser as mode locker and tunable filter

A wavelength-tunable actively mode-locked erbium fiber ring laser was demonstrated using a distributed feedback semiconductor laser as an intensity mode locker and a tunable optical filter. Very stable optical pulse trains at gigabit repetition rates were generated using harmonica mode locking. The supermode noise was suppressed to 60 dB below the signal level and the root-mean-square timing jitter (0.45 kHz–1 MHz) was found to be about 1% of the pulse duration. A continuous wavelength tuning range of 1.8 nm was achieved by changing the semiconductor laser temperature from 11.4 to 30 °C.

Actively mode-locked erbium fiber ring laser using a Fabry–Perot semiconductor modulator as mode locker and tunable filter

A wavelength-tunable actively mode-locked erbium fiber ring laser was demonstrated using a Fabry–Perot semiconductor modulator. The modulator played the simultaneous roles of an intensity mode locker and a tunable optical filter. Stable single- or dual-wavelength nearly transform-limited picosecond pulses at gigabit repetition rates were generated. Continuous wavelength tuning was achieved by simply controlling the temperature of the modulator. Pulse train with a repetition rate up to 19.93 GHz (eight times the driving frequency) was obtained by using rational harmonic mode-locking technique.

A Polarization-Maintaining and Dispersion-Managed 10-GHz Mode-Locked Erbium Fiber Ring Laser Providing Both sech2- and Gaussian-Shaped Pulses

We have constructed a polarization-maintaining and dispersion-managed 10-GHz regeneratively mode-locked Erbium fiber ring laser which generates highly stable and nearly transform-limited 3.5- to 7-ps sech2pulses at 1560 nm. By forcing the wavelength to a narrow-band ripple in the transfer function of the laser in-line filter, highly stable 15-ps Gaussian-like pulses were also obtained. We have studied in detail the temporal and spectral shapes of the pulses and confirmed a good agreement with the corresponding theoretical fits for transform-limited sech2and Gaussian pulses, respectively. The pulses have a timing jitter below 0.2 ps and the highest reported supermode noise suppression of 90 dB. This remarkably high supermode noise suppression is likely a result of the dispersion-management in the laser cavity. The wavelength is tunable within 1530–1570 nm. The laser has excellent long-term stability and is very robust to thermal and mechanical disturbances.

Active harmonic modelocking of an erbium fiber laser with intracavity Fabry-Perot filters

We present both experimental and theoretical investigations of the operation of a harmonically modelocked erbium fiber ring laser stabilized by an intracavity bit-rate etalon. Our model analyzes the effects of cavity components and operating parameters on laser stability and output pulse characteristics. The model predicts the output pulsewidth variation with laser cavity parameters such as cavity length, dispersion, and finesse of intracavity Fabry-Perot etalons. If the laser cavity length is not optimized, a maximum 50% increase in pulsewidth can occur at 5 Gb/s pulse rate. A repetition rate etalon with a finesse of 50 is sufficient to provide a side-mode suppression ratio of over 50 dB in the laser output. We also discuss how detuning from the optimal modulation frequency increases the excess noise that affects the laser stability. The theory predicts a maximum detuning range of /spl plusmn/100 kHz, which agrees with the experimental observations. These theoretical results can guide the design of similar lasers over a wide range of operating parameters.

10 GHz, 2 ps regeneratively and harmonically FM mode-locked erbium fibre ring laser

A 10 GHz regeneratively and harmonically FM mode-locked erbium fibre ring laser is reported for the first time. The output pulse width is 2 ps and the spectral width is 1.4 nm, resulting in a time bandwidth product of 0.34. The output pulse is almost transform limited, despite the FM mode-locking. This can be attributed to the anomalous group velocity dispersion which compensates for the up-chirping. The down-chirping does not evolve into stable FM mode-locking because it is reduced by the self phase modulation occurring in the long cavity.

Performance characterization of a harmonically mode-locked erbium fiber ring laser

We describe the performance of a harmonically mode-locked, erbium fiber ring laser. Transform-limited pulses with durations of 20-50 ps at 5.044 GHz repetition rate are obtained. The modulation frequency can be detuned by up to /spl plusmn/70 kHz and the lasing wavelength can be varied over the entire erbium gain bandwidth. Pulsewidths and pulse bandwidths are measured as a function of modulation power and frequency detuning. The laser is actively stabilized by locking intra-cavity Fabry-Perot etalon passbands to the laser modes. >

Ultrastable harmonically and regeneratively modelocked polarisation-maintaining erbium fibre ring laser

The authors report the operation of a harmonically and regeneratively modelocked erbium fibre ring laser at 1.55 µm for the first time. Harmonic regenerative modelocking was achieved by feeding back the harmonic longitudinal beat signal which was detected with a high speed photodetector and a high Q dielectric filter. The repetition rate was 10 GHz and the soliton effect shortened the pulse width from 7.0 to 2.7 ps.

Optically controlled wavelength-adjustable passively modelocked erbium-doped fibre ring laser

An integrated all-fibre technique has been used to implement wavelength tunability in a passively mode-locked erbium fibre ring laser. A smooth, continuous tuning range of 4 nm controlled simply by varying the power of an optical pump beam has been demonstrated.

Self-starting additive pulse mode-locked erbium fibre ring laser

Nonlinear polarisation rotation has been used to additive pulse mode-lock (APM) a single loop erbium fibre ring laser. The system is fully self-starting without triggering and has been made to produce single pulses of 452 fs duration per round trip time.

Selfstarting, passively modelocked erbium fibre ring laser based on the amplifying Sagnac switch

A novel self-starting, passively mode-locked erbium fibre laser is reported. The scheme is based on the reflection properties of a nonlinear amplifying loop mirror and provides a stable source of picosecond pulses.