Dual-wavelength 10-GHz actively mode-locked erbium fiber laser

We present the first 10 GHz dual-wavelength actively mode-locked erbium fiber laser (ML-EFL). Dual-wavelength operation is achieved by introducing two intracavity branches, each containing a tunable optical bandpass filter. A variable output coupler combining the filter branches also equalizes the effective cavity gain for the two wavelengths, By adjusting the filters and the coupler, dual-wavelength ML-EFL operation is achieved at different wavelengths. Nearly transform-limited, 4- and 6.2-ps-wide 10-GHz soliton pulses are e.g., simultaneously generated at 1542.3 and 1563.8 nm, respectively. The experimental results agree very well with analytical calculations     

Tunable monolithic colliding pulse mode-locked quantum-well lasers

The tunabilities of both the wavelength and the pulse-width of monolithic mode-locked semiconductor lasers are demonstrated. Pulses shorter than 1.6 ps, tunable over 8.8 mu m, have been generated by a temperature-tuned monolithic colliding pulse mode-locked (CPM) quantum-well laser. For a fixed wavelength, the pulse-width is independently controlled from 1.2 ps to longer than 3 ps by external bandpass filters. Near transform-limited time-bandwidth products of 0.34 were maintained throughout the tuning processes.<>     

Multicolor single-wavelength sources generated by a monolithic colliding pulse mode-locked quantum well laser

The authors report on the separation of single longitudinal modes from the mode-locked program spectrum of a 300-GHz monolithic colliding pulse mode-locked (CPM) semiconductor quantum-well laser. Experimentally, the selected longitudinal mode shows a 10-dB reduction of low-frequency relative intensity noise compared to that of the selected mode from the same laser in continuous-wave (CW) lasing conditions. The strong phase coherence among the passively mode-locked longitudinal modes reduces the partition noise of the unlocked CW laser.<>     

40-GHz transform-limited pulse generation from FM oscillation fiber laser with external cavity chirp compensation

A 40-GHz frequency modulation oscillation fiber laser is demonstrated and the continuous-wave (CW) output is used for generating a high repetition rate short pulse train by external cavity chirp compensation. A 1.37-ps transform-limited pulse is obtained from its chirped, 488.1-GHz width CW output.     

Electrical subharmonic hybrid mode locking of a colliding pulse mode-locked laser at 28 GHz

This letter discusses electrical subharmonic hybrid mode locking (SHML) of a colliding pulse mode-locked (CPM) laser in InP. The CPM laser fabrication adopts a simple wet etching process and bisbenzocyclobutene planarization process for realizing planarized low-capacitance devices. The experimental results show, for the first time to our knowledge, stable emission of nearly transform-limited pulses at 28 GHz of a CPM laser synchronized to a clock source by SHML. We further describe careful optimization steps of dc and radio-frequency biasing conditions which lead to minimal output pulsewidth of 1.4 ps, limited by the saturable absorber dimension.     

Colliding pulse mode-locked laser

The fabrication and performance of a colliding pulse-mode locked laser with an intracavity saturable absorber is described. The laser has a threshold current of 65 mA and differential efficiency of 0.04 mW/mA when coupled into a single-mode fiber. Mode-locked pulses with ~1 ps pulse width at ~10 GHz has been obtained     

Dual-wavelength 10-GHz actively mode-locked erbium fiber laser incorporating highly nonlinear fibers

We demonstrated a dual-wavelength actively mode-locked erbium-doped fiber ring laser with 0.8-nm wavelength spacing at a repetition rate of 10 GHz. A 1-km highly nonlinear fiber is introduced in the nonpolarization-maintaining cavity to suppress the gain competition of the homogeneously broadened gain medium in a self-driven manner. Output pulses at 1557.36 and 1558.17 nm are generated simultaneously. Amplitude fluctuations less than 0.45% and 1.7% of two wavelengths are measured. The corresponding timing jitters are less than 80 and 90 fs, respectively.     

80-160-GHz mode-locked fiber ring laser synchronized to external optical pulse stream

The authors present a novel scheme to generate ultrahigh repetition rate picosecond pulses synchronized to an optical pulse stream in an actively mode-locked fiber ring laser. A monolithic Mach-Zehnder interferometer with integrated semiconductor optical amplifiers serves as an 80-GHz optically controlled modulator. 80-GHz transform-limited 2.1-ps Gaussian pulse with low timing jitter, extinction ratios up to 25 dB, and 5 mW of average output power are demonstrated. The laser is wavelength tunable over more than 15 nm around 1555 nm. At 160 GHz, 2.5-ps pulse trains with 3-mW output power are generated by rational harmonic mode locking.     

Multiwavelength 10-GHz picosecond pulse generation from asingle-stripe semiconductor diode laser

A single-stripe GaAs-AlGaAs semiconductor optical amplifier (SOA) has been used to generate four tunable wavelength-division multiplexed (WDM) channels simultaneously, each transmitting 12-ps pulses at 2.5 GHz, for an aggregate pulse rate of 10 GHz. Wavelength tuning over 18 nm has been demonstrated with channel spacing ranging from 0.8 to 2.1 nm. A potential spectral correlation across the multiwavelength spectrum has been studied in both experiment and simulation methods. These results show the potential for utilizing single stripe laser diodes as multiwavelength sources in WDM-TDM network     

利用皮秒扫描相机研究对撞脉冲锁模Nd:YAG激光器的输出特性

本文报道了用BWS—5KⅡ型皮秒扫描相机对CPM Nd:YAG激光器进行研究的实验结果。得到了激光脉冲宽度为10.1PS的最佳结果,而且还得到了锁模单脉冲的真实波形。同时利用扫描相机研究了染料浓度、染料盒偏离中心位置对输出脉冲宽度及波形的影响,使激光器处于最佳工作状态。     

Wavelength-tunable 40-GHz picosecond harmonically mode-locked fiber laser source

We demonstrate a novel 40-GHz mode-locked fiber laser that utilizes a single active device to provide both gain and mode-locking. The laser produces pulses as short as 2.2 ps, is tunable over a 27-nm band centered at 1553 nm, and exhibits long-term stability without cavity-length feedback control. The pulse train at 1556 nm was used in a 40-Gb/s transmission experiment over 45 km with a low 0.4-dB power penalty.     

Tunable transform-limited pulse generation using self-injectionlocking of an FP laser

Wavelength-tunable, near transform-limited pulses have been generated using a Fabry-Perot laser diode coupled to a fiber loop containing a fiber Fabry-Perot resonator (FFPR) and a polarization controller. The ratio of transmitted to reflected light from the loop can be adjusted using the polarization controller. Single-mode operation of the gain-switched laser is achieved by self-injection locking, which is induced by light reflected from the fiber loop. The resulting output pulse has a time-bandwidth product of 0.4 and is tunable over about 15 nm by varying the tuning voltage of the FFPR     

Generation of wavelength-tunable transform-limited pulses from amonolithic passively mode-locked distributed Bragg reflectorsemiconductor laser

Generation of wavelength tunable transform-limited picosecond pulses from a monolithic passively mode-locked distributed Bragg reflector (DBR) laser is demonstrated for the first time. A wide tuning range of 12 nm is realized by changing the refractive index of the passive DBR region through a thin-film heater embedded on the DBR section without causing significant changes in pulse characteristics     

16-wavelength 10-GHz actively mode-locked fiber laser with demultiplexed outputs anchored on the ITU-T grid

We propose and demonstrate a 16-wavelength polarization-maintaining fiber laser, actively mode-locked at 10 GHz. The fiber laser includes a 16-channel 100-GHz-spaced arrayed waveguide grating (AWG) in the laser cavity; therefore, the outputs are demultiplexed and the lasing wavelengths are anchored at the ITU-T grid. The multiwavelength lasing has been achieved by cooling the erbium-doped fiber in liquid nitrogen. Generation of simultaneous multiwavelength short pulses was 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.<>     

High pulse rate, mode-locked copper vapor laser

The operating characteristics of a compact copper vapor laser which displays self-mode-locked operation and is capable of operating at pulse rates to 150 kHz are described.     

20 GHz transform-limited optical pulse generation and bit-error-free operation using a tunable, actively modelocked Er-doped fibre ring laser

The authors report the generation of 20 GHz, 3.0-3.5 ps transform-limited optical pulses across the wavelength tunable range 1550-1557 nm using a wavelength tunable, polarisation-maintaining actively modelocked Er/sup 3+/-doped fibre ring laser. Stable bit-error-free modelocking operation is confirmed throughout the wavelength tuning range.<>     

Realization and modeling of a 27-GHz integrated passively mode-locked ring laser

We present a realization and the modeling of a 27-GHz integrated extended cavity ring laser that is passively mode-locked. The mode-locked ring laser is fabricated with active-passive integration. Experimental results show that internal reflections are the major factor affecting operation stability. Continuous-wave, self-pulsating, and in small windows of operation mode-locked regimes have been observed. Similar regimes have been observed in our bidirectional laser model. This model describes the semiconductor amplifier and the saturable absorber using rate equations. Our experimental and theoretical results are compared and discussed.     

40-GHz mode-locked fiber-ring laser using a Mach-Zehnder interferometer with integrated SOAs

A 40-GHz mode-locked fiber-ring laser based on an optically controlled modulator is presented and analyzed in detail. The modulator is a monolithic InGaAsP-InP Mach-Zehnder interferometer with integrated semiconductor optical amplifiers, which allows optical pulse generation synchronized to an external optical clock pulse stream. The laser generates nearly transform-limited Gaussian pulses of 2.5-ps width and up to 9-mW mean output power with less than 130 fs of timing jitter, and it is wavelength tunable over more than 30 nm. The relationship between key laser parameters and the output pulse characteristics is analyzed experimentally and numerically. An improved cavity design permits the generation of shorter pulses of 1.0-ps width.