Optical device and method for controlling such a device

A combined optical device comprising at least two optical devices, each of the at least two optical devices comprising:

• a light input;
• a light modulating means;
• a light output;
• and
• an optical amplification device arranged to amplify light travelling between the light modulating means and the light output,
• wherein:
• the optical amplification device comprises a first and a second serially connected post SOA (Semiconductor Optical Amplifier) unit;
• each of the post SOA units comprises at least one respective serially connected post SOA segment;
• the optical device is arranged to vary a light amplification by varying respective SOA bias voltages across the post SOA segments;
• a total SOA length of the first post SOA unit is relatively longer than a total SOA length of the second post SOA unit, which is relatively shorter;
• and
• the optical device is arranged to, during operation, always keep respective SOA bias voltages across each of the post SOA segments of the first post SOA unit forward biased at +0.5 V or more,
• wherein the combined optical device comprises a MUX (MUltipleXing) device arranged to combine light exiting through the respective outputs of the optical devices into one optical fiber.

A method for modulating light using an optical device comprising

• a light input;
• a light modulating means;
• a light output;
• and
• an optical amplification device arranged to amplify light travelling between the light modulating means and the output, in turn comprising a first and a second serially connected post SOA (Semiconductor Optical Amplifier) unit, each comprising at least one respective serially connected post SOA segment, wherein a total SOA length of the first post SOA unit is relatively longer than a total SOA length of the second post SOA unit, which is relatively shorter,
• which method comprises varying respective SOA bias voltages across the post SOA segments to achieve a desired amplification level of light passing the optical amplification device while keeping respective SOA bias voltages across the post SOA segments of the first SOA unit forward biased at minimum +0.5 V,
• wherein the optical device comprises at least two of the relatively shorter second post SOA units and one of the relatively longer first post SOA unit, and wherein the method comprises providing a respective constant SOA bias voltage across each of the post SOA segments comprised in the at least two relatively shorter second post SOA units so as to achieve a general amplification level, which respective constant SOA bias voltages each is either a forward or reverse biasing voltage with respect to each of the at least two relatively shorter second post SOA units, and
• wherein the method further comprises providing the variable SOA bias voltage across the post SOA segments comprised in the relatively longer first post SOA unit to achieve a desired amplification.

A method for modulating light using an optical device comprising

• a light input;
• a light modulating means;
• a light output;
• and
• an optical amplification device arranged to amplify light travelling between the light modulating means and the output, in turn comprising a first and a second serially connected post SOA (Semiconductor Optical Amplifier) unit, each comprising at least one respective serially connected post SOA segment, wherein a total SOA length of the first post SOA unit is relatively longer than a total SOA length of the second post SOA unit, which is relatively shorter,
• which method comprises varying respective SOA bias voltages across the post SOA segments to achieve a desired amplification level of light passing the optical amplification device while keeping respective SOA bias voltages across the post SOA segments of the first SOA unit forward biased at minimum +0.5 V,
• wherein the method also comprises a step in which light output from the output of the optical device is conveyed to a MUX (MUltipleXing) device, and is combined with light exiting through the output of a second integrated optical device, so that the respective light output from the optical devices is integrated into one single optical fiber.