Quoc Thai Nguyen

Bidirectional 2.5-Gb/s WDM-PON Using FP-LDs Wavelength-Locked by a Multiple-Wavelength Seeding Source Based on a Mode-Locked Laser

We experimentally investigate the operation of a cost-effective wavelength-division-multiplexed passive optical network (WDM-PON) based on wavelength-locked Fabry-Pérot laser diodes (FP-LDs). A single quantum-dash passively mode-locked laser (QD-MLL) is combined with an arrayed waveguide grating in WDM-PON architecture to provide a low-noise, coherent multiwavelength seeding source to injection-lock the FP-LDs for both downstream and upstream. The results show that the QD-MLL-injected FP-LD has the same performance when compared to the case of injection-locking by a low-noise external cavity laser. Error-free bidirectional transmission over 25 km for 16 channels with 42.7-GHz channel spacing is demonstrated at 2.5 Gb/s in the C -band and an optical budget higher than 30 dB is reached.

Using optical injection of Fabry-Perot lasers for high-speed access in optical telecommunications

In this paper we present our recent works on optical injection of Fabry-Perot laser diode for application in access networks. The injection-locked Fabry-Perot laser diode is used as low-cost colorless transmitters for high-speed optical access exploiting wavelength-division-multiplexing technology. The modification of main characteristics of Fabry-Perot laser such as spectral properties, noise and modulation is shown in injection-locking regime. The strong dependence of these properties onto injection parameters is also given. Finally, the operation of injection-locked Fabry-Perot laser diode in a wavelength-division-multiplexed optical access system using a novel multi-wavelength master source based on quantum-dash mode-locked laser is presented and its transmission performances at 2.5 Gb/s are reported.

Strong dependence of the Linewidth Enhancement Factor onto an externally injected optical signal for locked Fabry-Perot laser diodes

Injection-locking is based on the fact that the laser can be locked onto the frequency and the phase of an external injected optical signal. When a Fabry-Perot laser diode (FP LD) is locked onto a single-mode signal, its operation becomes single-mode. The injection-locked FP LD (IL-FP LD) has been proposed as a standard component for optical access network [1]. In this paper, we propose to study the Linewidth Enhancement Factor (LEF) of IL-FP LD and its dependence onto the injection parameters.

Simple method to measure laser linewidth using intensity noise spectrum based on Rayleigh Backscattering effect

The coherency, which is linked to the spectral linewidth, is an important property of a laser, as it strongly influences the system performances in various domains of application [1]. Several methods have been proposed to measure the laser linewidth, among which the Delayed Self-Heterodyne Technique (DSHT) [2]. In this paper, we propose a novel and simple method to measure the laser linewidth based on Rayleigh Backscattering (RB) effect. Our technique requires relative intensity noise (RIN) measurement. Contrary to DSHT, it avoids the use of an acousto-optic frequency-shifter, which infers the bandwidth detection and of a Mach-Zehnder interferometer.