Continuously-tunable external cavity laser
AssigneeNew Focus, Inc.
InventorsPaul Zorabedian, William B. Chapman, Michael Y. Jenq
Life of this patent
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Abstract
The present invention provides a continuously-tunable external cavity laser (ECL) with a compact form factor and precise tuning. A novel interference filter which may be used to tune the ECL provides an absence of mode-hopping and reduced feedback from both spurious interference and reflections in the external cavity. A novel tuning mechanism is disclosed which provides for mechanical FM tuning of a wide range ECL tuning elements such as: an interference filter, a diffraction element, and a retroreflector. A novel feedback circuit is disclosed which provides closed loop feedback for selecting output wavelength in a laser.
Claims35
A tunable external cavity laser, comprising:
- a gain medium to emit a beam;
- a tuning element moveably positioned in a path of the beam to provide feedback of a selected wavelength to the gain medium;
- and
- a voice coil actuator coupled to said tuning element and responsive to an electrical signal to position said tuning element in the path of the beam to provide feedback of a selected wavelength to the gain medium to tune the tunable laser.
A tunable external cavity laser, comprising:
- a gain medium to emit a beam;
- a tuning element moveably positioned in a path of the beam to provide feedback of a selected wavelength to the gain medium;
- an encoder recording along a length thereof indicia corresponding to at least one of positions of said tuning element and selected wavelengths of the beam;
- a reader for reading the indicia and one of said encoder and said reader coupled to said tuning element;
- and
- a positioner coupled to said tuning element to position said tuning element in the path of the beam to provide feedback of a selected wavelength to the gain medium to tune the tunable laser and said positioner positioning said tuning element such that the indicia read by said reader substantially corresponds with the selected wavelength.
A method for controlling the output wavelength of an external cavity laser, and the external cavity laser including a base, a gain medium to emit a beam, and a tuning element variably positioned in a path of the beam to provide feedback of a selected output wavelength to the gain medium to tune the external cavity laser;
- and the method for controlling comprising the acts of:
- moving the tuning element to successive positions across a position range;
- measuring a corresponding output wavelength at each of the successive positions across the position range, responsive to said moving act;
- recording indications of the corresponding output wavelengths along a length of an encoding medium coupled to a selected one of the base and the tuning element responsive to said measuring act;
- reading from the encoding medium the indications of the corresponding output wavelengths;
- and
- moving the tuning element to a selected position at which the indication of the corresponding output wavelength read in said act of reading corresponds with the selected wavelength.
A tunable external cavity laser comprising:
- a gain medium for emitting a beam;
- a retroreflector in a path of the beam;
- a first reflector and a second reflector positioned opposite and at an angle to one another in the path of the beam between the gain medium and the retroreflector to provide feedback of a selected wavelength to the gain medium to tune the laser;
- and
- a positioner for positioning at least one of said first reflector and said second reflector to vary a separation between the reflectors along the path of the beam, thereby tuning the laser.
Dependencies are inferred from the claim text.