Optical waveguides – With optical coupler – Input/output coupler
Reexamination Certificate
1999-09-30
2001-05-22
Schuberg, Darren (Department: 2872)
Optical waveguides
With optical coupler
Input/output coupler
C385S024000, C385S046000, C359S199200, C359S199200
Reexamination Certificate
active
06236781
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to an optical interconnection device and, more particularly, to a waveguide grating router that has a substantially flat passband.
BACKGROUND OF THE INVENTION
Waveguide grating routers are used in conventional lightwave systems as optical switches, multiplexers, demultiplexers, detectors, add/drop filters, one by N (1×N), N by one (N×1) splitters and N by N (N×N) arrays. Typically, such waveguide grating routers include an interconnection apparatus having a plurality of closely spaced input waveguides communicating with an input of a star coupler. An output of the star coupler communicates with an optical grating comprising a series of optical waveguides. Each of the grating waveguides differs in length with respect to its nearest neighbor by a predetermined fixed amount. The optical grating is further connected to an input of a second star coupler, the outputs of which form outputs of the switching, multiplexing, and demultiplexing apparatus. Waveguide grating routers are also frequently referred to as “frequency routing devices” and are further described in U.S. Pat. No. 5,002,350, issued Mar. 26, 1991 to C. Dragone, entitled “Optical Multiplexer/Demultiplexer” (hereinafter “Dragone 1”) and U.S. Pat. No. 5, 136,671, issued Aug. 4, 1992 to C. Dragone, entitled “Optical Switch, Multiplexer, and Demultiplexer” (hereinafter “Dragone 2”), both of which are hereby incorporated by reference.
Such frequency routing devices are employed as wavelength routers in optical networks to drop and add optical channels at various nodes in an optical network. A particular channel may pass through several routers without regeneration before leaving the network. For this reason, it is desirable for each frequency routing device to provide a maximally flat passband.
Known frequency routing devices do not efficiently provide a flat passband between a distinct one of the input ports and a distinct one of the output ports. U.S. Pat. No. 5,412,744, issued May 2, 1995 to C. Dragone, entitled “Frequency Routing Device Having Wide and Substantially Flat Passband” (hereinafter “Dragone 3”), and hereby incorporated by reference, discloses a frequency routing device in which a flat passband is achieved by combining a frequency routing device with a Y-branch coupler. One limitation of this device, however, is that there is an inherent loss of optical power due to the presence of the coupler.
Thus, there is a need for a waveguide grating router having a substantially flat passband, without the disadvantages of prior art systems.
SUMMARY OF THE INVENTION
In accordance with the principles of the present invention a duplicated-port waveguide grating router having a substantially flat passband is achieved while reducing optical power loss. In one illustrative embodiment, the duplicated-port waveguide grating router includes a first free space region for receiving an optical signal from at least one input waveguide. An optical grating comprising a plurality of waveguides is connected to the first free space region. The optical grating is defined by a plurality of unequal length waveguides. Connected to the optical grating is a second free space region. A plurality of output waveguides are connected to the second free space region, wherein the plurality of output waveguides includes at least two adjacent waveguides having ends remote from the second free space region. A 2×2 coupler having two input ports is connected to the remote ends of the two adjacent waveguides and two output ports, which are the output ports of the waveguide grating router. The duplicated-port waveguide grating router provides substantially identical specifiable passband widths within the two output ports.
The coupler, for example an evanescent coupler, realizes a substantially 90° phase difference between optical signals propagated within the two adjacent output waveguides that are coupled to produce the two identical, substantially flat passband spectral responses. Advantageously, there is no excess loss in the duplicated-port waveguide grating router, since portions of the input optical power are directed to each of the duplicate output ports and thus, not radiated out or lost, as in prior art waveguide grating routers.
REFERENCES:
patent: 5002350 (1991-03-01), Dragone
patent: 5136671 (1992-08-01), Dragone
patent: 5412744 (1995-05-01), Dragone
patent: 5706377 (1998-01-01), Li
patent: 6049644 (2000-04-01), Dragone
Doerr Christopher Richard
Giles Randy Clinton
Agere Systems Optoelectronics Guardian Corp.
Assaf Fayez
Brosemer Jeffrey J.
Schuberg Darren
LandOfFree
Duplicated-port waveguide grating router having... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Duplicated-port waveguide grating router having..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Duplicated-port waveguide grating router having... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2559222