Patent ID: 8488636

Claim:
A method for suppressing side modes during the use of a tunable laser ( 10 ) of MGY type, which laser ( 10 ) comprises an amplification section ( 11 ), a phase section ( 12 ) and a reflector section, which reflector section comprises a Y-branched waveguide, with a first branch ( 14 a ) and a second branch ( 14 b ), the method comprising: defining a point of operation of the laser ( 10 ) by feeding a respective current through the phase section ( 12 ), the first branch ( 14 a ) and the second branch ( 14 b ), where possible combinations of these currents span a three-dimensional space, in which elongated volumes ( 1 ) define combinations of currents for which the laser ( 10 ) is operated in the same mode; and defining two-dimensional sectional surfaces through a certain of said volumes ( 1 ) by holding the current through the phase section ( 12 ) constant and varying the current through the branches ( 14 a ; 14 b ), wherein the two branch currents ( 14 a ; 14 b ) are chosen within a certain surface ( 2 ) so that the point of operation (P) of the laser ( 10 ) is caused to be positioned along a line (L), which line (L) runs from the periphery of the surface ( 2 ) at a first side of the surface ( 2 ), through both the center (C) of the surface ( 2 ) and the point of operation (P), and to the periphery of the surface ( 2 ) at the opposite side of the surface ( 2 ), at a distance (A) from the periphery of the surface ( 2 ) which is within an interval of between 20% and 40% of the length of the line (L), wherein the point of operation (P) is selected so that both respective branch currents are smaller than at the center (C) of the surface ( 2 ).