A strictly nonblocking network based on nonblocking 4×4 optical switches

Recently, the demand for communication has been growing rapidly. Hence, optical multistage network technologies are more appreciated nowadays. A double-layer network is a strictly nonblocking network, and it has the lowest system insertion loss of non-dilated networks. A Beneš network is a rearrangeably nonblocking network, and it has the same system insertion loss as a double-layer network. We have proposed the use of modified polarization selection elements (PSEs). The system insertion loss, number of drivers, and number of required components of a double-layer network could be reduced if it is constructed with modified PSEs. A nonblocking 4×4 optical switch with two stages of polarization selective elements has been presented in our previous study. Based on this nonblocking 4×4 optical switch, we propose a strictly nonblocking network structure which features even lower system insertion loss than those of a double-layer network and a Beneš network. The signal-to-noise ratio of the proposed network structure is a constant, and is higher than the constraint, although it is lower than that of the double-layer network. The number of major components of the proposed network is less than that of a double-layer network and larger than that of a Beneš network, since a Beneš network is rearrangeably nonblocking. We also offer a routing algorithm for the new proposed network; the time complexity of the routing algorithm is O(1).     

An 8 mm length nonblocking 4×4 optical switch array

A novel single-mode-single-slip-structure S³ optical switch using carrier-induced refractive index change is proposed as a unit cell for a small polarization-independent nonblocking N×N optical switch array. Sixteen S³ optical switches have been integrated into a nonblocking 4×4 optical switch array on an InP substrate. The 8-mm-length InGaAsP/InP 4×4 optical array has shown satisfactory switching characteristics and is suitable for larger scale integration of optical switch arrays and also for integration with other active optical devices such as laser diodes     

1×4 optical interconnect using electronically controlledangle steering of spatial solitons

A novel optical interconnect based on electronically controlled angle steering of spatial solitons is demonstrated experimentally in AlGaAs slab waveguides. The basic operation and the layout of the device are described. A maximal lateral steering of 100 μm was achieved, which is sufficient for the separation of four output channels. Using this device as a building block should lend to the experimental realization of dynamically reconfigurable N×N optical crossconnects     

Performance of rearrangeable nonblocking 4×4 switch matriceson LiNbO3

The design, fabrication, and characterization of rearrangeable nonblocking 4×4 switch matrices and the development of a novel ITO (indium-tin-oxide)/Au multilayer electrode that leads to low switching voltages and low DC drift is reported. Results on electrode systems, insertion loss, crosstalk, tolerances in the coupling length, and stability obtained for eight fabricated matrices are given. In comparison to the SiO₂ buffer layers, a reduction in the switching voltage of a factor of 0.66 has been achieved. Insertion losses of fiber pigtailed modules are in the range between 4 and 7 dB. The crosstalk has still to be improved. The stability of the operating points of the switches has been analyzed, showing that the devices must be operated in closed dark housings with a passivation layer in order to avoid optical damage effects from ambient light and to protect them against physical and chemical influences     

Rearrangeably nonblocking 8×8 guided wave optical switch

The design and construction of a lithium niobate 8×8 optical switch with a rearrangeably nonblocking architecture is described. The design is compared with the more familiar strictly nonblocking architecture. The switch has 28 elements, a switching voltage of 26 V and a loss of 5.5 dB at 1.3 μm wavelength     

Uni- and bidirectional 4λ×560 Mb/s transmissionsystems using WDM devices based on wavelength-selective fusedsingle-mode fiber couplers

Four-wavelength-channel wavelength-division multiplexing (WDM) lab transmission system experiments with buried heterostructure (BH) lasers at 1200-, 1240-, 1280-, and 1320-nm wavelengths, all-fiber WDM devices, and 20-km single-mode link fiber at a 560-Mb/s bit rate demonstrated that unidirectional and bidirectional WDM transmission systems could be operated successfully by using all-fiber 4λ multiplexing, 4λ demultiplexing, or 4λ multiplexing/demultiplexing devices with a low insertion loss per wavelength channel (2.1-4.7 dB), enough optical far-end crosstalk attenuation (18-37 dB), and high optical near-end crosstalk attenuation (43-49 dB). It is concluded that the four-wavelength-channel WDM lab transmission system at 560 Mb/s mainly used as a test bed is not representative of future unidirectional trunk WDM systems. Such systems favor distributed feedback (DFB) lasers in the 1500-1560-nm wavelength range where fiber attenuation is lower than in the 1200-1320 nm wavelength range and where 1500-nm DFB lasers with a smaller linewidth do not limit the repeater distance as much because of mode partition noise     

4×4 OEIC switch module using GaAs substrate

A compact 4×4 optical switch module consisting of a monolithic 4-channel OEIC receiver chip, a 4×4 GaAs IC chip, and a 4-channel OEIC transmitter chip has been developed for the first time. The module offers good performance, without an optical loss, a bandwidth of more than 600 MHz, and a crosstalk between neighboring channels of less than -20 dB. It has a good switching and distributive performance for high speed optical input signals of 560 Mbit/s. The switch module is attractive for use in high data-rate optical communication systems, particularly in local area networks, CATV systems, and intra-office links     

4×4 digital optical matrix switch using polymeric oversizedrib waveguides

For the first time the concept of oversized rib waveguides has been employed in a complex integrated optical device. Using commercially available polymers, a strictly nonblocking 4×4 digital optical matrix switch with full functionality has been realized. The matrix consists of 24 1×2 switching elements and showed a polarization independent average crosstalk of -28.8 dB     

8×8 symmetric nonblocking integrated acoustooptic spaceswitch module on LiNbO3

An 8×8 symmetric nonblocking integrated acoustooptic space switch module has been realized on a Y-cut LiNbO₃ substrate, 1.0×10.0×37.0 mm in size. The switch module consists of a new hybrid beam expanding-collimating lens, a large aperture focusing lens, and a pair of four-element tilted surface acoustic wave (SAW) transducer arrays in a titanium-in-diffused channel-planar-channel composite waveguide. Experimental results of point-to-point nonblocking switching at the optical wavelength of 0.6328 μm, including an average crosstalk of -12.2 dB, optical switching efficiency of 25% at 125 mW RF drive power, carrier frequency increment of 13.5 MHz for switching between adjacent output channels and reconfiguration time of 0.4 μs have been obtained     

High-capacity optical storage using multiple wavelengths, multiplelayers and volume holograms

A system is proposed that combines both the multilayer storage and the wavelength multiplexing afforded by using volume holograms to enhance by several fold the optical data storage capacity of compact discs. The storage capacity and interchannel crosstalk are analysed as functions of data-channel wavelength separation and reading beam spot size. A storage capacity of 9.7 Gbyte per disc is provided when six layers and six wavelengths are used     

Parallel implementation of a 4×4-bit multiplier using amodified Booth's algorithm

The design of a 4×4-bit multiplier using the modified Booth's algorithm in 2-μm NMOS technology is discussed. The main features of this chip are its 62.5-MHz operating frequency and 31.5-mW power dissipation. The chip occupies an area of 1.37 mm². A novel adder-cum-subtractor circuit was designed to realize the arithmetic processing part     

Low loss and high extinction ratio strictly nonblocking 16×16thermooptic matrix switch on 6-in wafer using silica-based planarlightwave circuit technology

We describe a silica-based 16×16 strictly nonblocking thermooptic matrix switch with a low loss and a high extinction ratio. This matrix switch, which employs a double Mach-Zehnder interferometer (MZI) switching unit and a matrix arrangement to reduce the total waveguide length, is fabricated with 0.75% refractive index difference waveguides on a 6-in silicon wafer using silica-based planar lightwave circuit (PLC) technology. We obtained an average insertion loss of 6.6 dB and an average extinction ratio of 53 dB in the worst polarization case. The operating wavelength bandwidth completely covers the gain band of practical erbium-doped fiber amplifiers (EDFAs). The total power consumption needed for operation is reduced to 17 W by employing a phase-trimming technique which eliminates the phase-error in the interferometer switching unit     

4×4 arrays of FET-SEED embedded control 2×1optoelectronic switching nodes with electrical fan-out

We describe a 4 by 4 array of embedded control two input, one output optoelectronic switching nodes based on the field effect transistor self electro-optic effect device (FET-SEED) technology. The arrays have electrical fan-out to remove the loss associated with optical fan-out in the system application. Extensive testing was done on several arrays at 156 Mb/s per channel with optical switching energies below 100 fJ, with the output driver limiting the maximum data rate to 400 Mb/s. Power dissipation, noise margin, crosstalk, sensitivity to stray light, and uniformity of both threshold and output waveforms are also discussed     

4×4 GaAs/AlGaAs optical matrix switches with uniform devicecharacteristics using alternating Δβ electrooptic guided-wavedirectional couplers

Integrated 4×4 GaAs/AlGaAs optical matrix switches constructed from 12 electrooptic directional couplers have been realized. In order to achieve uniform device characteristics, molecular beam epitaxy and reactive ion beam etching were chosen as the crystal growth technique and waveguide fabrication technique, respectively, in addition to the simplified tree structure as a matrix switch architecture. As a result, matrix switches with quite uniform device characteristics, such as small switching voltage deviation and little path dependence in ±0.5-dB propagation loss, have been realized     

Performance of two 4×4 guided-wave photonic switching systems

Data from two photonic switching systems are presented, the first is a 4×4 crossbar, and the second is a 4×4 passive splitter/active combiner broadcast switch. The 4×4 crossbar has operated continuously and reliably for 18 months with no noticeable performance degradation. The 4×4 passive splitter/active combiner has operated for six months and yields excellent bit-error-rate (BER) performance at 1.7 Gb/s, showing that the influence of optical crosstalk in a small guided-wave optical switching system does not significantly affect the BER     

Microwave diplexer using magnetostatic surface and backward volume waves

An experimental diplexer based on magnetostatic wave propagation in a tangentially magnetised thin film of YIG is reported. The diplexer function is obtained by using the fact that magnetostatic surface and backward volume waves propagate in contiguous but nominally nonoverlapping frequency bands.     

4×4 polymer thermo-optic directional coupler switch at 1.55μm

An integrated 4×4 polymer thermo-optic switch at 1.55 μm is demonstrated for the first time. A fibre to fibre insertion loss of 10 dB, and extinction ratios of 17.5-19.5 dB were measured. The polarisation sensitivity was typically less then 0.5 dB and the response time was less then 1 ms. The electrical power consumption was found to be 70 mW per single switch     

Polarisation-independent LiNbO3 4×4 matrix switch

The first polarisation independent LiNbO₃ strictly non-blocking 4×4 matrix switch has been developed. This matrix switch has a 4-6 dB insertion loss at any incident polarisation with 1.3 μm wavelength and about 30 V switching voltage     

Compact, 4×4 InGaAsP-InP optical crossconnect with ascaleable architecture

An InP-InGaAsP 4×4 optical crossconnect occupying only 2×2 mm² was demonstrated by combining 16 1×2 optically amplified suppressed interference switches (OASIS) in a square array architecture. On/off ratios of 33±4 dB were measured by a majority of these elements and fiber-to-fiber insertion loss of 3 dB was obtained using additional on-chip amplification stages     

Polarization-insensitive, monolithic 4×4 InGaAsP-InP laseramplifier gate switch matrix

Monolithically integrated 4×4 semiconductor laser amplifier gate switch arrays comprising twenty-four integrated laser amplifiers have been designed, fabricated, and evaluated. Low fiber-to-fiber loss, low polarization dependence, high extinction ratio, and low crosstalk are reported