Optical signal interleaver

Details Optical signal interleaver Optical signal interleaver

1999-06-29

2001-01-02

Epps, Georgia (Department: 2873)

Optical: systems and elements

Optical modulator

Light wave temporal modulation

C359S237000, C359S618000, C385S002000

Utility Patent

active

06169626

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to optical signal communications. More particularly, the invention relates to an interleaver for use with multiple optical channels.
BACKGROUND OF THE INVENTION
As telecommunications usage increases as a result of, for example, increased Internet usage, increased types of communications, population growth, etc., telecommunications providers are required to provide greater voice- and data-carrying capacity. In order to reduce cost and the amount of time required to provide the increased capacity, wavelength division multiplexing (WDM) and dense wavelength division multiplexing (DWDM) have been developed, which provide increased capacity without requiring new fiber optic cables.
WDM and DWDM technologies combines multiple optical signals into a single fiber by transporting each signal on a different optical wavelength or channel. Multiplexing and demultiplexing of optical channels is typically accomplished with thin film optical filters. However, multiple layers of film are required to multiplex and demultiplex multiple channels, which increases the cost and complexity of a component. Another disadvantage of multiple layers of thin film for filtering is that the thin films break down over time, especially when operating under high power conditions.
Another approach to increasing fiber optic capacity is to use more closely spaced channels. For example, at one point in time, 200 GHz spacing was common for optical channels. At that time optical components were designed to operate on 200 GHz spaced channels. As the state of the art improved, 100 GHz spacing was used for optical channels. Optical components were then designed to operate on 100 GHz spaced channels and devices designed to operate on 200 GHz spaced channels had to be replaced of modified to operate on the 100 GHz spaced channels. This upgrade requirement can be very expensive for parties with extensive fiber optic equipment.
Similar upgrade requirements apply to other channel spacing changes (e.g., 100 GHz spacing to 50 GHz spacing). What is needed is an optical device that can be used for interfacing between different channel spacing schemes.
SUMMARY OF THE INVENTION
An interleaver and a deinterleaver for filtering optical signals is described. In one embodiment, an interleaver includes a beam splitter to split an input optical beam into a first sub-beam and a second sub-beam. The interleaver also includes an etalon coupled to receive the first sub-beam. The etalon has a reflective surface and an air gap, the reflective surface reflects signals passed through the air gap. The interleaver further includes a non-linear phase shifter coupled to receive the second sub-beam. The phase shifter modifies a phase of the second sub-beam. the modified phase of the second sub-beam causes constructive and destructive optical interference between the reflected first sub-beam and the reflected second sub-beam to cause a first subset of signals from the input optical beam to be directed to a first port and the second subset of signals from the input optical beam to be directed to a second port.
In one embodiment, a deinterleaver includes a circulator. A first deinterleaver component is optically coupled to the circulator. The first interleaver component has a first port optically coupled to the circulator, a beam splitter to split the input optical beam into a first sub-beam and a second sub-beam, an etalon coupled to receive the first sub-beam, the etalon having a reflective surface and an air gap, the reflective surface to reflect signals passed through the air gap, and a non-linear phase shifter coupled to receive the second sub-beam. The phase shifter modifies a phase of the second sub-beam. The modified phase of the second sub-beam causes constructive and destructive optical interference between the reflected first sub-beam and the reflected second sub-beam to cause a first subset of signals from the input optical beam to be directed to the first port and the second subset of signals from the input optical beam to be directed to an output port.
The deinterleaver also includes a second deinterleaver component optically coupled to the circulator. The second interleaver component has a first port optically coupled to the circulator to receive the first subset of signals from the circulator, a beam splitter to split the first subset of signals into a first sub-beam and a second sub-beam, an etalon coupled to receive the first sub-beam. The etalon has a reflective surface and an air gap. The reflective surface to reflect signals passed through the air gap. The second interleaver component also includes a non-linear phase shifter coupled to receive the second sub-beam. The phase shifter modifies a phase of the second sub-beam. The modified phase of the second sub-beam causes constructive and destructive optical interference between the reflected first sub-beam and the reflected second sub-beam to cause the first subset of signals from the input optical beam to be directed to an output port.


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