Generation of short optical pulses using strongly complex coupled DFB lasers

An optical pulse source, comprising:

• a first single mode DFB semiconductor laser having a first grating for generating light at a first frequency;
• a second single mode DFB semiconductor laser having a second grating for generating light at a second frequency;
• the lasers having a common active medium and shared optical path, the lasers providing light injection of light imposed on each other resulting in generation of a beat signal at a difference frequency of two lasers;
• a saturable absorber disposed for receiving the beat signal and providing an initial time compression thus transforming the beat signal into an initial train of optical pulses;
• an optical amplifier disposed to receive the initial pulse train after the absorber;
• an optical compressor disposed to receive the pulse train after the optical amplifier and compressing duration of pulses of the train, thus forming a train of short optical pulses having a pre-determined duration and a repetition rate,
• the first and second lasers, the saturable absorber and the optical amplifier being formed on the same chip.

An source of radiation, comprising:

• a first single mode DFB semiconductor laser having a first grating for generating light at a first frequency;
• a second single mode DFB semiconductor laser having a second grating for generating light at a second frequency;
• the lasers having a common active medium and shared optical path and providing mutual light injection into each other resulting in generation of radiation at a beat frequency of the first and second lasers,
• wherein the first and second DFB lasers comprise one of the gain coupled and loss coupled DFB lasers,
• wherein the active medium includes a multiple quantum well structure, and the first and second gratings are formed by etching grooves directly trough the multiple quantum well structures, and
• wherein each grating has a period comprising a first section and a second section with substantially all of the quantum well structures being etched away from the second section, thus providing no substantial photon emission in the second section and ensuring no substantial interaction between the lasers.

A source of radiation comprising:

• a first single mode DFB semiconductor laser having a first grating for generating light at a first frequency;
• and
• a second single mode DFB semiconductor laser having a second grating for generating light at a second frequency;
• the lasers having a common active medium and shared optical path and providing mutual light injection imposed on each other resulting in generation of radiation at a beat frequency of two lasers,
• wherein the first and second gratings have different periods and
• wherein the frequency of one of the lasers which is remote from an output facet does not fall within a stopband of the other laser which is closer to the output facet so that light emitted by the remote laser can pass through the shared optical path to the output facet.

An optical pulse source, comprising:

• a first single mode DFB semiconductor laser having a first grating for generating light at a first frequency;
• a second single mode DFB semiconductor laser having a second grating for generating light at a second frequency;
• the lasers having a common active medium and shared optical path, the lasers providing mutual light injection into each other resulting in generation of a beat signal at a difference frequency of two lasers;
• an optical compressor disposed to receive the beat signal and compressing the pulse duration of the signal, thus forming a train of short optical pulses having a pre-determined duration and a repetition rate;
• and
• means for stabilizing the frequency of one of the first and second lasers.

An optical pulse source, comprising:

• a first single mode DFB semiconductor laser having a first grating for generating light at a first frequency;
• a second single mode DFB semiconductor laser having a second grating for generating light at a second frequency;
• the lasers having a common active medium and shared optical path, the lasers providing mutual light injection into each other resulting in generation of a beat signal at a difference frequency of two lasers;
• and
• an optical compressor disposed to receive the beat signal and compressing the pulse duration of the signal, thus forming a train of short optical pulses having a pre-determined duration and a repetition rate;
• wherein the first and second gratings have different periods.