Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
1997-11-12
2001-03-20
Negash, Kinfe-Michael (Department: 2733)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S199200, C359S199200, C385S024000
Reexamination Certificate
active
06204946
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
This invention relates to optical devices for adding and dropping optical signals to an optical fiber carrying existing optical signals without interfering with the existing optical signals. More particularly, the present invention is directed to a wavelength division multiplex add/drop optical device using a micromirror array for transmitting and reflecting optical signals in an optical communications system.
II. Description of the Related Art
In wavelength division multiplexed optical networks it is increasingly important to be able to switch multiple independent wavelength signals into and out of a single fiber without disturbing the other channels. This task is presently accomplished by utilizing an assembly of separate components such as a pair of wavelength demultiplexers and a set of N two-by-two bypass exchange switches. As is known, one of the wavelength demultiplexers, also known as a router, separates a multifrequency optical input data signal into N multiple fibers, with each fiber carrying a single wavelength. The bypass exchange switches accept the added and dropped channels. The other wavelength multiplexer combines the existing wavelengths with the added wavelengths onto a single fiber for transmission in the communications system. Among the drawbacks of such a discrete component approach, however, are the cost and size of the individual components and the resulting overall cost and size of the system.
SUMMARY OF THE INVENTION
A wavelength division multiplexed (WDM) transmit/reflect unit is disclosed for transmitting and reflecting select wavelengths of a multiwavelength optical signal onto optic fibers in an optic communications network. The transmit/reflect unit includes a lens positioned at a first port and a second port for directing the incoming optical signal to a planar grating wavelength multiplexer which angularly disperses the wavelengths in the signal. A focusing lens focuses the angularly dispersed wavelengths for receipt by a micromirror array switchable between a transmitting mode and a reflecting mode. The transmitting mode directs select wavelengths of the incoming signal from one port to the other port and the reflecting mode directs an incoming signal from the first port back to the first port.
A reconfigurable WDM add/drop device is also disclosed. The add/drop device employs a WDM transmit/reflect unit, of the type described above, which is disposed between first and second 3-port circulators. The first circulator interfaces with one port on the transmit/reflect unit and receives, from an input port, an input multiwavelength optical signal and outputs, to an output port, a multiwavelength optical signal. The second circulator interfaces with another port on the transmit/reflect unit. The second circulator receives, from. an add port, a wavelength to be added to the multiwavelength signal, and transmits, to a drop port, a wavelength to be dropped from the multiwavelength signal.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims.
REFERENCES:
patent: 5726785 (1998-03-01), Chawki et al.
patent: 5812291 (1998-09-01), Bendelli et al.
patent: 5926300 (1999-07-01), Miyakawa et al.
Aksyuk Vladimir A.
Bishop David J.
Ford Joseph E.
Walker James A.
Lucent Technologies - Inc.
Negash Kinfe-Michael
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