Z.G. Lu

312-fs pulse generation from a passive C-band InAs/InP quantum dot mode-locked laser.

For the first time, we report femtosecond pulses from a passive single-section InAs/InP quantum-dot (QD) mode-locked laser (MLL) with the active length of 456 microm and ridge width of 2.5 microm at the C-band wavelength range. Without any external pulse compression, the transform-limited Gaussian-pulses are generated at the 92 GHz repetition rate with the 312 fs pulse duration, which is the shortest pulse from any directly electric-pumping semiconductor MLLs to our best knowledge. The lasing threshold injection current and external differential quantum efficiency are 17.2 mA and 38%, respectively. We have also investigated the working principles of the proposed QD MLLs.

An L-band monolithic InAs/InP quantum dot mode-locked laser with femtosecond pulses

We have developed an InAs/InP quantum dot (QD) gain material using a double cap growth procedure and GaP sublayer to tune QDs into the L-band. By using it, a passive L-band mode-locked laser with pulse duration of 445 fs at the repetition rate of 46 GHz was demonstrated. The 3-dB linewidth of the RF spectrum is less than 100 KHz. The lasing threshold injection current is 24 mA with an external differential quantum efficiency of 22% and an average output power of 27 mW. The relationship between pulse duration and 3-dB spectral bandwidth as a function of injection current was investigated.

Ultrawide-bandwidth, superluminescent light-emitting diodes using InAs quantum dots of tuned height.

An ultrawide-bandwidth, superluminescent light-emitting diode (SLED) utilizing multiple layers of dots of tuned height is reported. Due to thermal effect, the superluminescent phenomenon is observed only under pulse-mode operation. The device exhibits a 3 dB bandwidth of 190 nm with central wavelength of 1020 nm under continuous-wave (cw) conditions. The maximum corresponding output power achieved in this device under cw and pulsed operation conditions are 0.54 mW and 17 mW, respectively.

Low noise InAs/InP quantum dot C-band monolithic multiwavelength lasers for WDM-PONs

A 50-GHz-spacing C-band multiwavelength laser (MWL) module based on an InAs/InP quantum-dot (QD) Fabry-Perot cavity has been developed for the first time. We have evaluated its system performance to show our QD-MWL potentials for WDM-PONs.

A widely tunable narrow-linewidth triple-wavelength erbium-doped fiber ring laser

A widely tunable narrow-linewidth simultaneous triple-wavelength oscillation erbium-doped fiber ring laser (EDFRL) is investigated in detail. The EDFRL can produce double-wavelength oscillations with the same polarization output, as well as another widely tunable wavelength oscillation with orthogonal polarization in both the C-band and the L-band. By preventing two polarization-mode competitions, we have achieved a stable single-longitudinal-mode triple-wavelength lasing output along with a minimum side-mode suppression ratio of 40 dB.

High-power multiwavelength Er/sup 3+/-Yb/sup 3+/ codoped double-cladding fiber ring laser

A high-power simultaneous multiwavelength lasing in an Er/sup 3+/-Yb/sup 3+/ codoped double-cladding fiber (EYCDF) ring laser is demonstrated based on a wavelength-dependent filter through spatial mode beating within the multimode fiber section. We have investigated the relationship between the lasing wavelengths and the length of the EYCDFs. The experimental results indicate that both the number of lasing wavelength lines and the spacing between two adjacent lasing lines can be controlled by the changes of the lasing light polarization states.

Ultra-broadband quantum-dot semiconductor optical amplifier and its applications

We have developed an ultra-broadband InAs/InGaAsP quantum-dot semiconductor optical amplifier around 1520 nm with the 3-dB bandwidth of 150 nm. The four-wave mixing process and multi-wavelength lasers have been demonstrated by using our QD-SOAs.

Three-stage wavelength converter based on cross-gain modulation in semiconductor optical amplifiers

A new cascaded three-stage all-optical wavelength converter based on cross-gain modulation (XGM) was analyzed and implemented using semiconductor optical amplifiers (SOAs) in a co-propagating arrangement. The optimal input powers of both pump and probe signals and the attenuation between the stages are discussed to achieve the highest on-to-off extinction ratio in each stage. A complete noise model was developed to calculate the bit error rate (BER), which is in good agreement with the experimental results. Power penalty free operation was achieved with the three-stage up-wavelength converter.

A dynamically gain-flattened erbium-doped fiber amplifier

We have investigated a dynamically gain-flattened erbium-doped fiber amplifier with a novel voltage-controlled fiber-based gain tilt controller. The detailed performance characteristics and the comparison results with a variable optical attenuator have been reported.

Single-mode 1.52 µm InAs/InP quantum dot DFB lasers

Single-mode InAs/InP quantum dot DFB lasers with side-mode suppression ratio greater than 62 dB are demonstrated, operating CW up to 80°C. Relative intensity noise was less than −153 dB/Hz from 1 MHz to 10 GHz.