US 2004/0165266 A1Published application

Broadband polarization transformation devices

AssigneePhotintech Inc.

InventorsTigran Galstian, Dany Dumont, Armen Zohrabyan, Amir Tork, Rouslan Birabassov

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Abstract

Broadband polarization transformation devices of various constructions are provided. The devices of the invention include a plurality of polarization switching elements that are either wavelength insensitive or used only in a wavelength insensitive manner. Preferably, 90° or 45° twisted liquid crystal cells which are electrically switchable and achromatic birefringent elements (such as Fresnel Rhombs) are used. In a particularly advantageous embodiment, the device is composed of, consecutively, a 90°TLC cell, a 45°TLC cell, a Fresnel Rhomb and an additionnal 45° TLC cell, allowing an initially linearly polarized light beam to be switched between the output polarization states p, s, σ, −σ, 45° and −45° depending on the application of voltages on the TLC cells.

Claims22

Dependent claims

A broadband polarization transformation apparatus for switching a polarization state of a light beam from a linear initial polarization state to one of a plurality of output polarization states irrespectively of a spectral distribution of said light beam, the apparatus comprising:

a switchable first polarization changing element having an input plane and two perpendicular polarization specific axes lying therein, the light beam impinging normally on said input plane with its initial polarization state aligned with one of said polarization specific axes;
first switching means for switching the first polarization changing element between a first mode outputting the light beam with its polarization rotated into alignment with the other one of said polarization specific axes, and a second mode outputting the light beam with its polarization unchanged;
a switchable second polarization changing element having an input plane and two perpendicular polarization specific axes lying therein in alignment with the polarization specific axes of the first polarization changing element, the light beam outputted from the first polarization changing element impinging normally on said input plane;
and
second switching means for switching the second polarization changing element between a first mode outputting the light beam with its polarization rotated by a predetermined angle, and a second mode outputting the light beam with its polarization unchanged.

2 more elements

Dependencies are inferred from the claim text.