Abstract: A communication system includes a communication unit with a first part and a number of a second part, where the second part is arranged to be placed at the location of an end user, and where the first part is common for a number of second parts. The first part and the second part respectively include a laser, and each second part is connected with the first part by a fiber optic cable and a frequency filter, the first part and the relevant second part being arranged to exchange information by laser light. Each second part includes a tunable laser, the first part is arranged to analyze light received from a second part, and to transmit information to the second part while the first part is receiving light from the second part, and the information contains information for the second part that it should adjust, where required, its frequency or wavelength, and the second part thus is arranged to change its frequency or wavelength.

Abstract: A communication system includes a communication unit with a first part and a number of a second part, where the second part is arranged to be placed at the location of an end user, and where the first part is common for a number of second parts. The first part and the second part respectively include a laser, and each second part is connected with the first part by a fibre optic cable and a frequency filter, the first part and the relevant second part being arranged to exchange information by laser light. Each second part includes a tunable laser, the first part is arranged to analyze light received from a second part, and to transmit information to the second part while the first part is receiving light from the second part, and the information contains information for the second part that it should adjust, where required, its frequency or wavelength, and the second part thus is arranged to change its frequency or wavelength.

Abstract: Alternative laser structures, which have potentially the same tuning performance as (S)SG-DBR and GCSR lasers, and a fabrication process which is similar to that of the (S)SG-DBR laser, are presented. The advantage of these structures is that the output power does not pass through a long passive region.

Abstract: The invention relates to the characterization of tunable lasers. One particular method of characterizing a semiconductor laser is useful for a laser having first and second tuning sections controlled by respective first and second tuning currents. The method includes measuring power output from the laser as a function of the first and second tuning currents, and creating an image of power as a function of the two tuning currents. The image is analyzed to determine different modes, each mode corresponding to limited ranges of the first and second tuning currents. A preferred combination of the first and second tuning currents is determined for each mode and an acceptable operating region is defined for each mode.

Abstract: Alternative laser structures, which have potentially the same tuning performance as (S)SG-DBR and GCSR lasers, and a fabrication process which is similar to that of the (S)SG-DBR laser, are presented. The advantage of these structures is that the output power does not pass through a long passive region.

Abstract: Alternative laser structures, which have potentially the same tuning performance as (S)SG-DBR and GCSR lasers, and a fabrication process which is similar to that of the (S)SG-DBR laser, are presented. The advantage of these structures is that the output power does not pass through a long passive region.