Crosspoint switch circuit and switch cell electronic circuit

Details Crosspoint switch circuit and switch cell electronic circuit Crosspoint switch circuit and switch cell electronic circuit

1999-12-20

2003-02-25

Tokar, Michael (Department: 2819)

Electronic digital logic circuitry

Multifunctional or programmable

Array

C326S101000, C307S113000

Reexamination Certificate

active

06525563

ABSTRACT:

BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a crosspoint switch circuit and a switch cell electronic circuit, and more particularly the present invention relates to a crosspoint switch circuit and a switch cell electronic circuit suitable for use in a channel switching function unit necessary for a transmitting apparatus (e.g., an optical cross-connect apparatus or an optical ADM (Add Drop Multiplexer) or the like) utilized on an optical network using WDM (Wavelength Division Multiplex) technology.
(2) Description of the Related Art
Recently, as is represented by the Internet, demand in communication is dramatically increasing. In order to cope with the increase of demand in communication, it becomes indispensable to build a photonic network having a great amount of capacity capable of transmitting a signal at an ultrahigh bit-rate (e.g., ten gigabit to about terabit in the future) using the WDM technology, as is shown schematically in
FIG. 21
, for example. When such a photonic network is built, the optical cross-connect apparatus (OXC) or the optical ADM are utilized in general.
The optical cross-connect apparatus (OXC) is an apparatus useful for receiving a WDM signal and capable of generating (cross-connect) any channel signal in the unit of wavelength (channel) (see FIG.
22
). The optical ADM is an apparatus for carrying out Add/Drop/Through control in the unit of channel on the received WDM signal, whereby an optical signal on a certain channel transmitted from a desired network is inserted (added) to a main channel signal, an optical signal on a certain channel is extracted from the main channel signal and branched (dropped) to the desired network, and an optical signal on a certain channel in the main channel is sent through the apparatus without any drop operation (see FIG.
23
).
Therefore, if the optical cross-connect apparatus or the optical ADM are provided in a desired area upon request as shown in
FIGS. 22 and 23
, then signals transmitted in any network such as a transmission network of SDH (Synchronous Digital Hierarchy), SONET (Synchronous Optical Network), ATM (Asynchronous Transfer Mode) or the like can be transmitted in a form of optical signal at a high bit-rate to a desired network in the unit of channel. Thus, it is possible to build an optical network capable of providing a flexible transmission service.
To this end, it is necessary for the above-described optical cross-connect apparatus or the optical ADM to be equipped with a switching system for switching the optical signal channel. That is, the optical cross-connect apparatus requires a switch of a multi-input and multi-output type (so called crosspoint switch) in which WDM signal transmission paths established in a bundle of optical fibers are dynamically switched in the unit of channel. The optical ADM requires a crosspoint switch capable of diverting an optical signal of all the channels from the main channel so as to switch the connection destination.
As for the crosspoint switch, a type of optical (space) switch is now under research and development in which the channel switching can be carried out with maintaining the mode of the signal as an optical signal. As one representative optical switch, named is a PI-LOSS (Path-independent Insertion on Loss) type optical switch. The PI-LOSS type optical switch has an arrangement in which, as for example shown in
FIG. 24
, a plurality of optical waveguides
101
are formed on a substrate
100
so that they cross one another at crosspoints (Sxy:1≦x≦4, 1≦y≦4) and temperatures at the crosspoints are controlled to change the refractive index at the crosspoint, whereby the optical signal path is switched.
In more specifically, the temperature of the crosspoints are controlled so that only one of the crosspoints Sxy of the optical path
101
becomes the bar status and all other crosspoints of the optical path
101
become the cross status. Thus, optical signals sent to an input highway #x can be outputted to an output highway #y. For example, if only the crosspoint S
12
(x=1, y=2) is controlled to be the bar status, the optical signal sent to the input highway #
1
will pass through a path indicated with a bold solid line shown in FIG.
24
and finally outputted at the output highway #
2
.
That is, according to the above-described PI-LOSS type optical switch, each of the crosspoints Sxy is formed into a switch cell of a two-input two-output type, and the switch cells are arrayed and interconnected one another to form a matrix of four rows and four columns (4×4). Then, one of the switch cells Sxy is controlled to be the bar status in its connecting status, thus any one of the input highway #x can be connected to any output highway #y.
Since the PI-LOSS type optical switch has the arrangement described above, the following merits can be obtained, for example.
{circle around (1)} The number of crosspoints (switch cell) Sxy that the optical signal undergoes becomes constant (four in the example shown in
FIG. 24
) regardless of choice of the optical path. Therefore, the optical signal from the input terminal to any of the output highway #y through each path is subjected to the same amount of loss, with the result that there is no scattering expected in the optical signal level deriving from each of the output highway #y.
{circle around (2)} Since the switch cells Sxy are interconnected one another byway of the optical waveguides
101
, crosstalk between paths can be effectively suppressed.
The above-described PI-LOSS type optical switch of a size of 8×8 is brought into a practical application stage. The PI-LOSS type optical switch is arranged as a non-blocking type switch.
On the other hand, a crosspoint switch made of an electronic circuit (hereinafter sometimes referred to as simply “electric switch”) is placed under research and development by manufactures. This is because if the network employs the optical cross-connect apparatus or the optical ADM, in order to compensate the loss of the signal caused in the process of signal transmission, the received signal is often once received and terminated by a receiver within the apparatus so that the optical signal is converted into an electric signal. Thus, there is a circumstance that the electric switch is more applicable than the optical switch.
The most popular type of the electric switch has a mesh structure (lattice arrangement with N inputs and G outputs: N and G are integers greater than 1) as for example shown in FIG.
25
. The above electric switch has advantages that it can be manufactured with ease to be more small-sized, less expensive and lower electric consumption as compared with the above-introduced optical switch. Now, electric switch
200
having 16×16 input and output ports capable of dealing with a signal of ten gigabit (Gb/s) at an ultrahigh rate is under the stage of research and development.
Incidentally, if a large-sized (large capacity) optical network mainly composed of a WDM system of multi-wavelength (e.g., 32 wavelengths or more are simultaneously transmitted per fiber) is requested to build, the crosspoint switch employed in the above-described situation is requested to deal with a signal of an ultra-high bit-rate (10 Gb/s) whichever the signal is of the optical mode or electric mode. Further, the crosspoint switch is requested to be independent of the signal bit-rate. For example, if the network employs the optical ADM, the crosspoint switch utilized in the network shall be arranged to have at least 16×16 input and output terminals. If the network employs the optical cross-connect apparatus, the crosspoint switch utilized in the network shall be arranged to have at least 512×512 input and output terminals.
However, as has been described above, as the crosspoint switch which can deal with a signal of an ultra-high bit-rate (about 10 Gb/s) and arranged as a single-stage link arrangement, the largest crosspoint switch that has been successfully devel

Affiliated with

Also associated with

Rating

Crosspoint switch circuit and switch cell electronic circuit does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Crosspoint switch circuit and switch cell electronic circuit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Crosspoint switch circuit and switch cell electronic circuit will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3170574