Optical isolators with ultra-low polarization mode dispersion
AssigneeOplink Communications, Inc.
InventorWei-Zhong Li
Life of this patent
Estimating the term…
Abstract
This invention presents a novel tunable module that can be incorporated in various optical devices, to provide a tunability and selectivity in a characteristic of an optical signal by effectively modifying its optical path lengths. The present invention also provides an optical isolator that incorporates such a tunable module, so that polarization mode dispersion is minimized to an arbitrarily low level. The present invention further describes methods for incorporating the tunable module in optical devices and for tuning the optical characteristics.
Claims71
A tunable module incorporated in an optical apparatus, the optical apparatus comprising a Faraday rotator disposed between a first polarizer and a second polarizer along an optical path, wherein said first polarizer and said second polarizer are arranged such that any light traveling from said second polarizer to said first polarizer will be effectively blocked, said tunable module comprising:
- at least two optical elements, wherein at least one of said optical elements is a movable element such that an optical path length of an optical signal traversing through said tunable module can be varied.
An optical apparatus with arbitrarily low polarization mode dispersion, the optical apparatus comprising:
- one or more optical devices;
- and
- a tunable module in optical communication with said one or more optical devices, said tunable module comprising at least two optical elements, wherein at least one of said optical elements is a movable element such that an optical path length of an optical signal traversing through said module can be varied.
An optical apparatus for optical fibers comprising:
- a Faraday rotator disposed between a first polarizer and a second polarizer along an optical path, wherein said first polarizer and said second polarizer are arranged such that any light traveling from said second polarizer to said first polarizer will be effectively blocked;
- and
- a tunable module disposed in said optical path on either side of said Faraday rotator, comprising at least two optical elements, wherein at least one of said optical elements is a movable element such that an optical path length of an optical signal traversing through said module can be varied.
An optical apparatus for optical fibers comprising:
- a) a Faraday rotator disposed between a first polarizer and a second polarizer along an optical path, wherein said first polarizer and said second polarizer are arranged such that any light traveling from said second polarizer to said first polarizer will be effectively blocked, and wherein at least one of said polarizers is a movable polarizer such that an optical path length of an optical signal traversing through said movable polarizer can be varied;
- and
- b) a compensation plate disposed in said optical path on either side of said Faraday rotator.
A method for tuning an optical apparatus, comprising:
- a) disposing an optical device in the path of an optical signal;
- b) disposing a tunable module comprising at least two optical elements in the path of said optical signal, wherein at least one of said optical elements is a movable element such that an optical path length of said optical signal traversing through said module can be varied;
- and
- c) adjusting the position of said movable element so to vary said optical path length of said optical signal, while monitoring a characteristic of said optical signal using a detection means, until said characteristic falls within a predetermined range, wherein said characteristic of said optical signal is polarization mode dispersion.
A method for making an optical apparatus, comprising:
- a) disposing a Faraday rotator between a first birefrigent polarizer and a second birefrigent polarizer along an optical path, wherein said first polarizer and said second polarizer are arranged such that any light traveling from said second polarizer to said first polarizer will be effectively blocked;
- b) disposing a tunable module comprising at least two optical elements of birefrigent material on either side of said Faraday rotator in said optical path, wherein at least one of said optical elements is a movable element such that optical path lengths of an optical signal traversing through said module can be varied;
- c) arranging a fast axis of said tunable module to be perpendicular to a fast axis of the polarizer on the same side of said Faraday rotator;
- and
- d) adjusting the position of said movable element to vary the optical path lengths of said optical signal, while monitoring the polarization mode dispersion of said optical signal using a detection means, until the polarization mode dispersion is minimized.
Dependencies are inferred from the claim text.