Erbium Fiber Ring Laser Research Articles

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.

High-repetition-rate FM oscillation in an erbium fiber ring laser and its application for picosecond pulse generation by external chirp compensation

Higher-harmonic FM oscillation of an Er-fiber laser is demonstrated and the constant amplitude output is used for generating a high repetition rate short pulse train by compression. Chirped, constant-amplitude FM light of 193-GHz width was generated, at 1.56 μm at a repetition rate of 7.3 GHz, by applying detuned phase perturbation of 131 kHz to the ring cavity. The output was compressed using a 2-km-long anomalous-dispersion fiber and this resulted in a stable train of 4.3-ps pulses and corresponded to a compression ratio of 32. The experimental results are found to be in good agreement with the calculated results.

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.

10 GHz modelocked, dispersion-managed and polarisation-maintainingerbium fibre ring laser with variable output coupling

A 10 GHz regeneratively modelocked, dispersion-managed and polarisation-maintaining erbium fibre ring laser has been constructed with a variable outcoupling; it produced very stable and nearly chirp-free 3.2 – 8.1 ps sech2 pulses at 1560 nm. It is experimentally shown that the stable operation region of the ML-EFRL is extended by increasing the laser output coupling.

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.

Electrooptic narrow linewidth wavelength tuning and intensity modulation of an erbium fiber ring laser

We report an electrically tunable fiber laser featuring a 50-channel wavelength switching capability with a 0.2 nm linewidth and -20 dB crosstalk. The laser consists of an Er-doped fiber resonator and an electro-optic TE-TM convertor used as a wavelength tunable filter. It allows wavelength tuning over a spectral range of 10 nm with a tuning rate of 0.05 nm/V and a linewidth of 0.06 nm.

10 GHz, 2 ps regeneratively and harmonically FMmode-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.

Single-frequency erbium fibre ring laser withintracavity phase-shifted fibre Bragg gratingnarrowband filter

The authors report a single-frequency unidirectional erbium fibre ring laser operating at 1.55 /spl mu/m which uses an intracavity phase-shifted fibre Bragg grating as an ultranarrow frequency bandpass filter. The linewidth of the laser was measured to be <2.0 kHz.

Optical modelocking at 10 GHz using a highly nonlineargermanosilicate optical fibre

The authors report the optical modelocking of an erbium fibre ring laser at 10 GHz using only 20 m of a highly nonlinear germania-doped silica fibre that has been developed for use in all-optical processing applications. >

Tunable, single frequency erbium fiber laser using an overlay bandpass filter

We describe a single frequency, unidirectional erbium fiber ring laser. Wavelength selection is performed by a ‘‘continuous fiber’’ filter of the fiber to planar waveguide coupler type. Varying the refractive index experienced by the exposed surface of the filter allowed the single longitudinal mode output from the laser to be tuned, discretely, from 1556–1561 nm with a resolution limited linewidth of 52 kHz.

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 modelockedpolarisation-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.

Soliton propagation without transmission controlusing a phase-locked erbium fibre ring laser

2.5 Gbit.s-1 solitons have been transmitted a distance of 17 600 km in a recirculating loop without transmission control. To achieve this a new stabilisation technique for modelocked erbium fibre lasers has been implemented. Cavity length changes are tracked with an electronic phaselock loop and the phase of the RF drive adjusted accordingly.

Optically controlled wavelength-adjustable passivelymodelocked 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.

Transmission of a true single polarisation 40 Gbit/s soliton data signal over 205 km using a stabilised erbium fibre ring laser and 40 GHz electronic timing recovery

Four independently modulated 10 Gbit/s channels were transmitted over 205 km with a penalty of less than 1.5 dB. The pulse source comprised a stabilised 10 GHz erbium fibre ring laser, multiplexed to 40 Gbit/s in a single polarisation by four independent lithium niobate modulators. Following transmission the requirement to kick start the demodulator is avoided using a 40 GHz electronic clock recovery circuit with a 10 GHz output. The experiment is performed entirely with commercial components and semiconductor laser diodes.

Harmonically mode-locked fiber ring laser with an internal Fabry–Perot stabilizer for soliton transmission

We describe a modulator-driven, erbium-fiber ring laser that produces chirp-free pulses with width adjustable over the range of 5 to 100 ps. A high-finesse Fabry-Perot étalon with a free spectral range equal to the 2.5-GHz laser repetition rate eliminates unwanted laser ring modes and stabilizes the pulse amplitude. Using this laser, we have extended the error-free distance of a series of soliton transmission experiments by 2000-3000 km over previous results with a mode-locked semiconductor laser.

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.

Output power characteristics of erbium-doped fiber ring lasers

The output power of an erbium-doped fiber ring laser has been measured as a function of pump power, emission wavelength, doped-fiber length, and reflectivity of the output coupler. A theoretical model for the calculation of the output power is introduced that is based on a previously derived gain equation for erbium-doped fiber amplifiers. The calculated values are in good agreement with the experimental data, confirming the applicability of the theory to a reliable modeling of the output power of erbium fiber ring lasers. >

High-speed, mode-locked, tunable, integrated erbium fibre laser

A diode-pumped, integrated erbium fibre ring laser has been mode-locked at frequencies up to 14 GHz using a high speed lithium niobate amplitude modulator. Pulses of 20–30 ps duration have been generated with mean output powers of 7.5 mW. In addition, the laser could be efficiently tuned over the 1.52–1.57μm wavelength region.

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.