Julien Poette

Chromatic Dispersion in 60 GHz Radio-Over-Fiber Networks Based on Mode-Locked Lasers

Chromatic dispersion is a limiting factor in intensity-modulated radio-over-fiber links with direct detection. This paper investigates its influence on single-mode fiber links based on mode-locked laser sources through simulation and experiment. A time-based approach is used to describe the impact of chromatic dispersion after transmission across a single-mode fiber link. The simulations presented herein give hints for the design of dedicated mode-locked lasers that can later serve in dispersion-tolerant radio-over-fiber networks. The findings of the simulations are experimentally validated for a laser delivering a 60 GHz radio carrier, and for a link of 400 m length which represents a realistic link length for in-house distribution. Furthermore, the impact of chromatic dispersion on signal quality is demonstrated for WLAN transmission employing direct and external link modulation.

Highly-sensitive measurement technique of relative intensity noise and laser characterization

A sensitive technique to measure the relative intensity noise of a laser is described. Such experiment is a useful tool for laser characterizations, allowing direct measurement of physical parameters like relaxation oscillation frequencies and damping factor. Examples of determination of such parameters are given.

HIGHLY SENSITIVE MEASUREMENT TECHNIQUE OF RELATIVE INTENSITY NOISE AND LASER CHARACTERIZATION

A sensitive technique to measure the relative intensity noise of a laser is described. Such experiment is a useful tool for laser characterizations, allowing direct measurement of physical parameters like relaxation oscillation frequencies and damping factor. Examples of determination of such parameters are given.

Analog link performance of mode-locked laser diodes in the 60 GHz range

In this paper, we present an experimental link performance analysis of mode-locked laser based radio-over fiber systems operating in the millimeter-wave range around 60 GHz. Both directly and externally modulation links are evaluated in terms of maximum output power, link loss, system noise figure and achievable dynamic range. Key parameters for the design and system application of mode-locked laser diodes are identified.

Measurement of intensity noise correlation between lines of spatially distributed multi-wavelength fiber lasers

Photoinscription of superstructured Bragg gratings in Er-Yb codoped fiber is a promising and cost-effective approach to produce high-quality multi-wavelength fiber lasers for various applications like radio-over-fiber systems, fiber-optic sensors or low-cost WDM testing source. However, a good understanding of the noise properties of the laser source is required before these applications can be addressed. Previous modeling has shown that these devices are similar to compact cascades of single wavelength DFB fiber lasers in which the modes at each wavelength are almost nonoverlapping along the fiber. In this paper, we further examine the independence of each channel by performing relative intensity noise (RIN) measurements on a multi-wavelength fiber laser, a dual-polarization fiber laser and a dualwavelength fiber laser. In each case, we estimate the correlation between the laser lines. From RIN measurements performed on each channel of a multi-wavelength laser, as well as on the full spectrum, we compute an average degree of correlation between the RIN of neighboring lines and observed no correlation in most of the cases. Moreover, each channel displays a single relaxation frequency which is different from those of the other channels. On the other hand, we observed strong partition noise, with negative correlation, between polarization modes of a single wavelength fiber laser. Finally, we measured the RIN of the two modes of a dual-wavelength fiber laser with modes having a greater overlap than the multi-wavelength laser. The results show that the lines share two common relaxation frequencies, an indication of a dynamic link between them.

Experimental investigation of relaxation oscillations resonance in mode-locked Fabry-Perot semiconductor lasers

We propose in this communication an experimental study of the relaxation oscillations behavior in mode-locked lasers. The semiconductor self-pulsating laser diode is composed by two gain sections, without saturable absorber. It is made of bulk structure and designed for optical telecommunication applications. This specific device allows two different regimes of optical modulation: the first one corresponds to the resonance of the relaxation oscillations and the second one, to the mode-locking regime at FSR value. This singular behavior leads us to characterize the self-pulsations which are coexisting in the laser and to describe two regimes of output modulation: the first one appears thanks to the resonance of the oscillation relaxation and the other one corresponds to the FSR of the Fabry-Perot laser at 40 GHz.