Electro-optic modulator
AssigneeCoherent LaserSystems GmbH & Co. KG
InventorsRüdiger Von Elm, Wolf Seelert
Life of this patent
Estimating the term…
Abstract
An electro-optic modulator for a laser beam includes an yttrium vanadate crystal cooperative with a double-pass electro-optic switch. A beam to be modulated passes through the yttrium vanadate crystal and makes a forward and a reverse pass through the electro-optic switch. The electro-optic switch returns the beam to the vanadate crystal selectively in one of two polarization orientations at 90 degrees to each other. Depending on the polarization orientation, the returned beam is transmitted by the crystal along a corresponding one of two about-parallel paths spaced apart from each other.
Claims14
Electro-optic modulator apparatus for modulating a laser-beam plane-polarized in a first polarization-orientation, the apparatus comprising:
- a first birefringent crystal configured and arranged to receive the laser-beam and transmit the laser-beam along a first path dependent on the first polarization-orientation;
- a double-pass electro-optic switch including at least a second birefringent crystal cooperative with an end-mirror, and configured and arranged to receive the laser-beam polarized in the first-polarization orientation from the first birefringent crystal and return the laser-beam to the first birefringent crystal selectively plane-polarized in either the first polarization-orientation when the second birefringent crystal is inactive or in a second polarization-orientation at ninety-degrees to the first polarization when the second birefringent crystal is activated, and
- wherein the electro-optic switch and the first birefringent crystal are further configured and arranged such that if the laser-beam is returned to the first birefringent crystal in the first polarization-orientation, the laser-beam is transmitted by the first birefringent crystal on a second path displaced from the first path by a first amount, and if the laser beam is returned to the first birefringent crystal in the second polarization-orientation, the laser-beam is transmitted by the first birefringent crystal along a third path laterally displaced from the first path by a second amount, with the second amount being larger than the first amount.
A method of operating a modulator for selectively directing a plane polarized input laser beam along an exit path, said modulator including a first and second birefringent crystals, said method comprising:
- directing the laser beam sequentially into the first and second birefringent crystals and then sequentially back through the second and first birefringent crystals, said first and second birefringent crystals being arranged so the beam exiting the first birefringent crystal is displaced from the beam entering the first birefringent crystal by a first amount;
- and
- activating the second birefringent crystal in a manner to rotate the polarization of the laser beam by ninety degrees such that when the beam passes through the first birefringent crystal the second time, the path of the beam is displaced such that upon exiting the first birefringent crystal, the beam is displaced from the beam entering the first birefringent crystal by a second amount, the second amount being larger than the first amount.
Dependencies are inferred from the claim text.