Time and wavelength division switching system

Claim 2

A time and wavelength switch comprising: a plurality of wavelength selector means for selecting a time division multiplexed (TDM) channel of a first wavelength from a plurality of incoming TDM channels of different wavelengths; and a plurality of time-slot switching and wavelength conversion stages connected respectively to the outputs of said wavelength selector means for deriving a signal of a second time slot and a second wavelength from a first time slot of said selected TDM channel.

Claim 3

A time and wavelength switch as claimed in claim 1, wherein said time-slot switching and wavelength conversion stages comprise: a plurality of time-slot switching means (4) connected respectively to the outputs of said wavelength selector means (3) for switching said first time slot of said selected TDM channel to said second time slot; and a plurality of wavelength convertor means (5) connected respectively to the outputs of said time-slot switching means for converting the wavelength of said second time slot to said second wavelength.

Claim 4

A time and wavelength switch as claimed in claim 1, wherein said time-slot switching and wavelength conversion stages comprise: a plurality of wavelength converter means (23) connected respectively to the outputs of said wavelength selector means for converting the wavelength of said selected TDM channel to said second wavelength; a plurality of time-slot switching means (24-26) connected respectively to the outputs of said wavelength convertor means for switching said first time slot of said TDM channel of said second wavelength to said second time slot.

Claim 5

A time and wavelength switch as claimed in claim 1, wherein said time-slot switching and wavelength conversion stages comprise: a plurality of sets of wavelength converter means (45) each having a hysteretic output level characteristic to maintain optical energy supplied thereto; a plurality of first optical switching means (43) associated respectively with said sets of wavelength converter means and having input terminals connected respectively to the outputs of said wavelength selector means (42), each of said first optical switching means (43) having a plurality of output terminals connected respectively to the inputs of said wavelength converter means (45) of the associated set for coupling said selected TDM channel to one of said wavelength converter means (45) of the associated set to cause same to convert said first wavelength of said selected TDM channel to said second wavelength and maintain said converted second wavelength; and a plurality of second optical switching means (44) associated respectively with said sets of wavelength converter means (45), each of said second optical switching means having a plurality of inputs connected respectively to the outputs of said wavelength converter means (45) of the associated set for extracting a portion of said maintained second wavelength time coincident with said second time slot.

Claim 6

A time and wavelength division multiplexed optical switching system comprising: a plurality of first time and wavelength (T x W) switches each comprising a plurality of wavelength selector means for selecting a time division multiplexed (TDM) channel of a first wavelength from a plurality of incoming TDM channels of different wavelengths, and a plurality of time-slot switching and wavelength conversion stages connected respectively to the outputs of said wavelength selector means for deriving a signal of a second time slot and a second wavelength from a first time slot of said selected TDM channel; a plurality of branching couplers (11) having inputs connected respectively to the outputs of said first T x W switches, said input of each of said branching couplers being branched out to a plurality of outputs; a plurality of sets of optical devices (G1-Gn; F1-Fn; S1-Sn, G1-Gn) having inputs connected respectively to the outputs of said branching couplers (11) for selecting one of said second time slot and said second wavelength; a plurality of combining couplers (12) having inputs connected respectively to the outputs of said optical devices, said input of each of said combining couplers being combined to an output of each of the combining couplers; and a plurality of second time and wavelength (T x W) switches connected respectively to the outputs of said combining couplers (12), each of said second T x W switches comprising a plurality of wavelength selector means for selecting said second wavelength, and a plurality of time-slot switching and wavelength conversion stages connected respectively to the outputs of said wavelength selector means for deriving a signal of a third time slot and a third wavelength from said second time slot of said selected second wavelength.

Claim 7

A time and wavelength division multiplexed optical switching system comprising: a plurality of first time and wavelength (T x W) switches each comprising a plurality of wavelength selector means for selecting a time division multiplexed (TDM) channel of a first wavelength from a plurality of incoming TDM channels of different wavelengths, and a plurality of time-slot switching and wavelength conversion stages connected respectively to the outputs of said wavelength selector means for deriving a signal of a second time slot and a second wavelength from a first time slot of said selected TDM channel; a plurality of branching couplers (11) having inputs connected respectively to the outputs of said first T x W switches, said input of each of said branching couplers being branched out to a plurality of outputs; a plurality of sets of optical devices (G1-Gn; F1-Fn; S1-Sn, G1-Gn) having inputs connected respectively to the outputs of said branching couplers (11) for selecting one of said second time slot and said second wavelength; a plurality of combining couplers (12) having inputs connected respectively to the outputs of said optical devices, said input of each of said combining couplers being combined to an output of each of the combining couplers; and a plurality of second time and wavelength (T x W) switches connected respectively to the outputs of said combining couplers (12), each of said second T x W switches comprising a plurality of wavelength selector means for selecting said second wavelength, and a plurality of time-slot switching and wavelength conversion stages connected respectively to the outputs of said wavelength selector means for deriving a signal of a third time slot and a third wavelength from said second time slot of said selected second wavelength.

Claim 8

A time and wavelength division multiplexed optical switching system as claimed in claim 5, wherein said time-slot switching and wavelength conversion stages comprise: a plurality of time-slot switching means (4) connected respectively to the outputs of said wavelength selector means (3) for switching said first time slot of said selected TDM channel to said second time slot; and a plurality of wavelength convertor means (5) connected respectively to the outputs of said time-slot switching means for converting the wavelength of said second time slot to said second wavelength.

Claim 9

A time and wavelength division multiplexed optical switching system as claimed in claim 5, wherein said time-slot switching and wavelength conversion stages comprise: a plurality of wavelength converter means (23) connected respectively to the outputs of said wavelength selector means for converting the wavelength of said selected TDM channel to said second wavelength; a plurality of time-slot switching means (24-26) connected respectively to the outputs of said wavelength convertor means for switching said first time slot of said TDM channel of said second wavelength to said second time slot.

Claim 10

A time and wavelength division multiplexed optical switching system as claimed in claim 5, wherein said time-slot switching and wavelength conversion stages comprise: a plurality of sets of wavelength converter means (45) each having a hysteretic output level characteristic to maintain optical energy supplied thereto; a plurality of first optical switching means (43) associated respectively with said sets of wavelength converter means and having input terminals connected respectively to the outputs of said wavelength selector means (42), each of said first optical switching means (43) having a plurality of output terminals connected respectively to the inputs of said wavelength converter means (45) of the associated set for coupling said selected TDM channel to one of said wavelength converter means (45) of the associated set to cause same to convert said first wavelength of said selected TDM channel to said second wavelength and maintain said converted second wavelength; and a plurality of second optical switching means (44) associated respectively with said sets of wavelength converter means (45), each of said second optical switching means having a plurality of inputs connected respectively to the outputs of said wavelength converter means (45) of the associated set for extracting a portion of said maintained second wavelength time coincident with said second time slot.

Claim 11

A time and wavelength division multiplexed optical switching system as claimed in any one of claims 5 to 8, wherein each of said optical devices comprises an optical gate (G1-Gn), further comprising control means (14) for sequentially activating said optical gates of a first set associated with first inputs of said combining couplers and sequentially activating said optical gates of a second set associated with second inputs of said combining couplers at times (t1, t2, ..... tm) displaced with respect to the times (tm, t1 ..... tm-1) at which said optical gates of said first set are activated.

Claim 12

A time and wavelength division multiplexed optical switching system as claimed in any one of claims 5 to 9, wherein said optical devices comprise a plurality of sets of wavelength filters (F1-Fn), said wavelength filters of each set having different wavelengths from those of the same set but identical to those of the other sets, the wavelengths (λ1, λ2, .... λn) of the wavelength filters of a first set associated with first inputs of said combining couplers being different from the wavelengths (λn, λ1 ... λn-1) of those of a second set associated with second inputs of said combining couplers.

Claim 13

A time and wavelength division multiplexed optical switching system as claimed in any one of claims 5 to 10, wherein said optical devices comprise a plurality of sets of wavelength selector means (S1-Sn, G1-Gn) each being responsive to a time-slot coincident pulse applied thereto for extracting a signal in said second time slot of said second wavelength.

Claim 14

A time and wavelength division multiplexed optical switching system comprising: a source for generating a plurality of time division multiplexed (TDM) channels of different wavelengths; coupling means (230) connected to said source for coupling said TDM channels to a plurality of outputs; a plurality of wavelength selector means (400) connected respectively to the outputs of said coupling means for selecting one of said TDM channels in response to a wavelength selection command signal applied thereto; a plurality of optical gate means (401) connected respectively to the outputs of said wavelength selector means for selecting a time slot of said selected TDM channel in response to a time slot selection signal applied thereto; and a plurality of subscriber terminals respectively associated with said optical gates, each of said terminals having an optoelectrical converter coupled through an optical transmission medium to the output of the associated optical gate.

Claim 15

A time and wavelength division multiplexed optical switching system comprising: a source for generating a plurality of time division multiplexed (TDM) channels of different wavelengths; coupling means (230) connected to said source for coupling said TDM channels to a plurality of outputs; a plurality of wavelength selector means (400) connected respectively to the outputs of said coupling means for selecting one of said TDM channels in response to a wavelength selection command signal applied thereto; a plurality of optical gate means (401) connected respectively to the outputs of said wavelength selector means for selecting a time slot of said selected TDM channel in response to a time slot selection signal applied thereto; and a plurality of subscriber terminals respectively associated with said optical gates, each of said terminals having an optoelectrical converter coupled through an optical transmission medium to the output of the associated optical gate.

Claim 16

A time and wavelength division multiplexed optical switching system as claimed in claim 12, further comprising a plurality of optical bistable devices (500) having a hysteretic output level characteristic and connected respectively to the outputs of said optical gate means (401) to maintain output signals for a period longer than the duration of said time slot, and a plurality of optical gate means (501) connected respectively to the outputs of said optical bistable devices for extracting a portion of output signals from the bistable devices in response to said time slot selection signal, said portion being longer than the duration of said time slot.

Claim 17

A time and wavelength division multiplexed optical switching system as claimed in claim 12 or 13, further comprising: a branching coupler (600) for branching an output of said coupling means to a plurality of output terminals; a plurality of second wavelength selector means (601) connected respectively to said output terminals of said branching coupler for selecting one of said TDM channels in response to a wavelength selection command signal applied thereto; a plurality of second optical gate means (602) connected respectively to the outputs of said second wavelength selector means for selecting a time slot of said selected TDM channel in response to a time slot selection signal applied thereto; a plurality of controlled optical delay means (603, 604) connected respectively to the outputs of said optical gate means (602) for introducing a delay time longer than the duration of the time slot to output signals of said optical gate means (602) in the presence of a control signal applied thereto, applying the delayed signals to output terminals thereof and for coupling the output signals of optical gate means (602) to the output terminals thereof in the absence of said control signal; a coupler (605) for coupling the output terminals of said controlled optical delay means to one end of an optical transmission medium; and an optoelectrical converter coupled to the other end of said optical transmission medium; a time division demultiplexer (608) connected to the output of said optoelectrical converter; and a plurality of subscriber terminals connected respectively to the outputs of said time division demultiplexer.

Claim 18

A time and wavelength division multiplexed optical switching system comprising: a branching coupler (600) for branching an output of said coupling means to a plurality of output terminals; a plurality of second wavelength selector means (601) connected respectively to said output terminals of said branching coupler for selecting one of said TDM channels in response to a wavelength selection command signal applied thereto; a plurality of second optical gate means (602) connected respectively to the outputs of said second wavelength selector means for selecting a time slot of said selected TDM channel in response to a time slot selection signal applied thereto; a plurality of optical bistable devices (700) connected respectively to the outputs of said optical gate means (602) for stretching the duration of output signals of said optical gate means (602) in response to a control signal applied thereto; means (701) for extracting portions of the outputs of said optical bistable devices (700) at different times from each other and for coupling the extracted portions to one end of an optical transmission medium; an optoelectrical converter (607) coupled to the other end of said optical transmission medium; a time division demultiplexer (702) connected to the output of said optoelectrical converter; and a plurality of subscriber terminals connected respectively to the outputs of said time division demultiplexer (702).

Claim 19

A time and wavelength division multiplexed optical switching system comprising: a branching coupler (600) for branching an output of said coupling means to a plurality of output terminals; a plurality of second wavelength selector means (601) connected respectively to said output terminals of said branching coupler for selecting one of said TDM channels in response to a wavelength selection command signal applied thereto; a plurality of second optical gate means (602) connected respectively to the outputs of said second wavelength selector means for selecting a time slot of said selected TDM channel in response to a time slot selection signal applied thereto; a plurality of optical bistable devices (700) connected respectively to the outputs of said optical gate means (602) for stretching the duration of output signals of said optical gate means (602) in response to a control signal applied thereto; means (701) for extracting portions of the outputs of said optical bistable devices (700) at different times from each other and for coupling the extracted portions to one end of an optical transmission medium; an optoelectrical converter (607) coupled to the other end of said optical transmission medium; a time division demultiplexer (702) connected to the output of said optoelectrical converter; and a plurality of subscriber terminals connected respectively to the outputs of said time division demultiplexer (702).