US Patent:
20040165641, Aug 26, 2004
Inventors:
Arnaud Garnache - Montpillier cedex, FR
Daniele Romanini - Grenoble, FR
Marc Levenson - Campbell CA, US
Robert Lodenkamper - Sunnyvale CA, US
Frederic Stoeckel - Vaulnaveys Le Haut, FR
Alexandre Katchanov - Sunnyvale CA, US
Guido Knippels - Sunnyvale CA, US
Barbara Paldus - Sunnyvale CA, US
Christopher Rella - Sunnyvale CA, US
Bruce Richman - Sunnyvale CA, US
International Classification:
H01S003/08
H01S003/082
Abstract:
An optical fiber transmitter for emitting an information-carrying laser beam comprises an optically or electrically pumped single mode MQW (multi-quantum well) semiconductor amplifying mirror as a gain medium and a separate external reflector to form a cavity. The external cavity length defines a comb of optical modes, all or a subset of which correspond to channel wavelengths of an optical telecommunications system having plural optical channels. The semiconductor gain element has a homogeneously broadened gain region; a tuning arrangement tunes the laser from mode to mode across the gain region, thereby selecting each one of the plural optical channels. When the maximum gain bandwidth is less than mode-to-mode spacing defined by the cavity, the tuning arrangement includes a means of altering the temperature of the amplifying mirror, thereby translating the frequency of the gain peak from one mode to another. An optical modulator adds modulation to provide an information-carrying laser beam, and a coupler couples the information-carrying laser beam into an optical fiber of the optical telecommunications system. A calibration method based on detecting inter-mode optical transitions (mode hopping) is described. The parameters of the amplifying mirror and tuning arrangement can be adjusted during operation to switch quickly from one cavity mode to another in stepwise fashion.