Lin Jin-tong

Generation and performance Investigation of 40GHz phase stable and pulse width-tunable optical time window based on a DPMZM

We experimental demonstrate stable, simple and pulse width-tunable 40 GHz short time window generation using a dual parallel Mach-Zehnder modulator (DPMZM) driven simply by an electrical clock. The pulse widths are measured to be tunable continuously from 5.6 ps to 12.6 ps by simply adjusting the DC bias voltage of DPMZM. The timing jitter, extinction ratio (ER), optical signal-to-noise ratio (OSNR) and insertion loss (IL) of the generated width-tunable time window are measured to be better than 50 fs, 18 dB, 50 dB and 16 dB respectively.

Towards 640 Gbit/s wavelength conversion based on nonlinear polarization rotation in a semiconductor optical amplifier

Taking into account ultra-fast carrier dynamics, this paper models 640 Gbit/s wavelength conversion scheme based on nonlinear polarization rotation (NPR) in a single semiconductor optical amplifier (SOA) and investigates the performance of this kind of wavelength conversion scheme in detail. In this model, two carrier temperature equations are introduced to substitute two energy density equations, which reduce the complexity of calculation in comparison with the previous model. The temporary gain and phase shift dynamics induced by ultra-short optical pulses are numerically simulated and the simulated results are qualitatively in good agreement with reported experimental results. Simulated results show that non-inverted and inverted 640 Gbit/s wavelength conversions based on NPR are achieved with clear open eye diagrams. To further investigate the performance of the non-inverted wavelength conversion scheme, the dependence of output extinction ratio (ER) on some key parameters used in simulation is illustrated. Furthermore, simulated analyses show that high performance non-inverted wavelength conversion based on NPR can be achieved by using a red-shifted filtering scheme.

Single mode rate equations for two sections self-pulsating DFB laser

We propose a set of single mode rate equations for multi-section distributed feedback (DFB) lasers. On the basis of the rate equations, the self-pulsation in the two-section DFB lasers with asymmetrical injection current was explained. It was found that the dynamic distribution of the power in two sections play key role in the self-pulsation running.

Design and optimization of evanescently coupled waveguide photodiodes

We present the design and optimization of evanescently coupled waveguide photodiodes (EC-WPDs) based on the coupling modes theory and the beam propagation method. Efficient focalization of the optical power in the absorber is achieved by an appropriate choice of index matching layers of EC-WPDs. Numerical simulation shows that high-speed (40 GHz), high quantum efficiency (81%) and high linearity photodiodes can be achieved, and EC-WPDs are promising devices for future optical communication systems.

Third-order intermodulation distortion improvement radio-over-fiber link using dual-wavelength intensity modulation

In this paper, we present a novel scheme using dual-wavelength lights to suppress the nonlinear intermodulation distortion in intensity-modulated radio-over-fiber link both theoretically and experimentally. More than 26 dB suppression of the third-order intermodulation distortion (IMD3) is achieved after 5.1km single mode fiber transmission; and the error vector magnitude of the proposed scheme is reduced from 18.26% to 8.06% after linearization.

Spacing-adjustable and wavelength-tunable multiwavelength fibre laser with nonlinear Brillouin gain and birefringence fibre loop mirror

This paper demonstrates a room-temperature multiwavelength fibre laser with spacing-adjustability and wavelength-tunability. The nonlinear gain of self-excited stimulated Brillouin scattering can suppress mode competition induced by homogeneous broadening of Erbium-doped fibre. With the use of a birefringence fibre loop filter, the wavelength spacing can be adjusted by changing the length of the used birefringence fibre, and the lasing wavelengths can be finely tuned through modifying the filtering profile of the birefringence filter. Multiwavelength output with spectral spacing as small as 0.076 nm and a wavelength number of more than 80 has been successfully produced.

Comparision of three kinds of wavelength conversion schmes based on nonlinear polarization rotation

Taking into account ultra-fast carrier dynamics, we model 640Gbit/s wavelength conversion based on nonlinear polarization rotation (NPR) in a single semiconductor optical amplifier (SOA) and investigate the performance of three kinds of wavelength conversion schemes: one only based on NPR and the other two based on NPR assisted with sideband filtering. Simulated results show that the three kinds of wavelength conversion schemes are achieved with clear open eye diagrams and have signal regeneration capability at 640Gbit/s. To further investigate the performance of three kinds of wavelength conversion schemes, the dependence of output extinction ratio (ER) on some key parameters used in simulation is illustrated. Simulated analyses show that the wavelength conversion based on NPR assisted with blue-shifted filtering scheme exhibits the best performance in terms of the maximum output ER for wavelength conversion and the maximum dynamic range of input power for signal regeneration.

640Gbit/s all-optical demultiplexing using nonlinear polarization rotat in semiconductor optical amplifier

Taking into account ultra-fast carrier dynamics, we have numerically analyzed 640Gbit/s to 80Gbit/s demultiplexing scheme based on nonlinear polarization rotation (NPR) in a single semiconductor optical amplifier (SOA) in detail. Simulated results show that there is a trade-off in the width and amplitude of switching window induced by clock pulse in terms of the input clock pulse energy. The rise time of switching window does not strongly depend on clock pulse energy, whereas the FWHM and fall time of switching window are increasing with the increase of the clock pulse energy. We have also obtained demultiplexing results from 640Gbit/s to 80Gbit/s based on NPR with a clear open eye diagram. From the simulated analyses, it is clear that for the higher output channel suppression ratio, the input clock signal with TE mode is required.

Period-Doubling in 10 GHz Gain-Switched DFB Laser Diode

The distinct period doubling behaviour in a 10 GHz gain-switched (GS) DFB laser is experimentally investigated in frequency domain and in time domain. The period doubling occurs as the frequency of the rf driving signal is close to or higher than the -3 dB cutoff frequency of the DFB laser diode, and the amplitude of the rf driving signal required to achieve period doubling increases linearly with the increasing bias current of the laser diode.

Optical Pulse Generation with Self-Cascaded Electroabsorption Modulator

A novel scheme for pulse generation with a self-cascaded electroabsorption modulator is presented and experimentally demonstrated at 10 GHz. In the case of optimal tuning of time delay in the fibre loop, the improvement of 50% on pulsewidth with improved extinction ratio is obtained and the narrowest pulse generated with this method is about 11 ps.