Discrete mode lasers for communications applications

Abstract

The wavelength spectra of ridge waveguide Fabry Perot lasers can be modified by perturbing the effective refractive index of the guided mode along very small sections of the laser cavity. One way of locally perturbing the effective index of the lasing mode is by etching features into the ridge waveguide such that each feature has a small overlap with the transverse field profile of the unperturbed mode, consequently most of the light in the laser cavity is unaffected by these perturbations. A proportion of the propagating light is however reflected at the boundaries between the perturbed and the unperturbed sections. Suitable positioning of these interfaces allows the mirror loss spectrum of a Fabry Perot laser to be manipulated. In order to achieve single longitudinal mode emission, the mirror loss of a specified mode must be reduced below that of the other cavity modes. Here we review the latest results obtained from devices containing such features. These results clearly demonstrate that these devices exceed the specifications required for a number of FTTH and Datacomms applications, such as GEPON, LX4 and CWDM. As well as this we will also present initial results on the linewidth of these devices.

Fast Random Bit Generation Using a Chaotic Laser: Approaching the Information Theoretic Limit

“…Semiconductor lasers subjected to polarization-rotated feedback exhibit a rich variety of complex phenomena [18]. The system consists of a single semiconductor edge-emitting laser (Eblana Discrete Mode Laser) with a wavelength of 1.54 µm and with a threshold current of I th = 12.1 mA at 22 • C [19]. The full width halfmaximum (FWHM) of the optical spectra is ∼ 1 MHz at 15 mA and the laser package is built without optical isolators at the laser output.…”

Integrable Slotted Single-Mode Lasers

“…An exception is the slotted laser reported in [6][7][8][9][10][11][12][13]. These lasers use optical defects in a standard Fabry-Pérot (FP) laser to specifically select a single mode, and such optical defects are formed by etching around 1 µm wide slots into the top ridge of the laser waveguide.…”

“…These slots, if we consider them as a kind of grating, are generally very high order surface gratings. Up to now there have been two types of laser schemes based on these slots: one is the mode selective FP laser type [6][7][8][9][10][11], where the slots are seated inside the laser cavity. This type of laser needs two cleaved facets to form the fundamental FP cavity and uses the slots to select one single mode from the multiple modes of the FP cavity.…”