Discussion on RIN improvement using a standard coupler

Author

Thibon, Clément ; Dross, Frédéric ; Marceaux, Alexandre ; Vodjdani, Nakita

Author_Institution

Microwave Optoelectronics Team, Alcatel-Thales III-V Lab., Marcoussis, France

Volume

17

Issue

6

fYear

2005

fDate

6/1/2005 12:00:00 AM

Firstpage

1283

Lastpage

1285

Abstract

It is possible to increase the signal-to-noise ratio (SNR) of radio-frequency optical links by a factor of N by combining the light of N individual lasers. The individual relative intensity noises (RINs) are then averaged, and the equivalent noise is lowered. However in some cases, while using a standard 3-dB coupler for combining two lasers, some additional noise appears which limits the RIN (and, thus, the SNR) improvement. This noise is proved, in this letter, to originate from heterodyne beating between the peak of one laser and the sidemodes of the other laser. It is possible to suppress this additional noise by injecting the light beams in crossed polarization in the coupler. The experimental data found by doing so matches perfectly the expected behavior. A 3-dB RIN improvement can be achieved if the two lasers have the same output optical power and similar RIN.

Keywords

laser beams; laser noise; light polarisation; light sources; optical fibre communication; optical fibre couplers; RIN; coupler; crossed polarization; heterodyne beating; lasers; radio-frequency optical links; relative intensity noise; signal-to-noise ratio; Laser beams; Laser noise; Optical coupling; Optical fiber communication; Optical mixing; Optical noise; Optical polarization; Power lasers; Radio frequency; Signal to noise ratio; Laser beams; laser couplers; laser noise; light sources; noise measurement; optical couplers; optical noise; semiconductor laser arrays;

fLanguage

English

Journal_Title

Photonics Technology Letters, IEEE

Publisher

ieee

ISSN

1041-1135

Type

jour

DOI

10.1109/LPT.2005.846473

Filename

1432803