Dynamic Optical Interconnection Research Articles

Software-defined optical networking applications enabled by programmable integrated photonics

Data center networks are experiencing unprecedented exponential growth, mostly driven by the continuous computing demands in machine learning and artificial intelligence algorithms. Within this realm, optical networking offers numerous advantages, including low latency, energy efficiency, and bandwidth transparency, positioning it as a compelling alternative to its electronic counterparts. In this work, we showcase a range of software-defined optical networking applications deployed on a general-purpose programmable integrated photonic processor. Leveraging graph-based theory, we experimentally demonstrate dynamic optical interconnects, circuit switching, and multicasting on the same photonic platform, yielding remarkable results in terms of crosstalk and reconfiguration speed. Our approach harnesses the benefits of reconfigurability and reliability, paving the way for a new generation of high-performance optical devices tailored for data center and computing clusters.

Light propagation in periodic microcavities

We demonstrated light propagation in a type of optical waveguide, which consisted of periodically arrayed dielectric particles. Although the form is similar to a photonic crystal waveguide, our method used resonance frequencies instead of band-gap frequencies. Advantages provided by this waveguide are that dynamic optical interconnection can be realized and that a multichannel waveguide is easily formed. To fabricate the system of periodic microcavities, we used polystyrene-latex particles that have a uniform size of 15.6 μm. Some discrete frequencies of fluorescence were selected to agree with the phase matching condition and they were propagated through the microspheres. The assembled microspheres can be taken as a multichannel waveguide.

Compact polarization-based all-optical interconnection systems with growth capability

All-optical communication requires all-optical interconnections, thus leading to reliable, fast, and flexible modular communication means in future systems. Free-space approaches are advantageous since they fully use the two dimensions optics offer. A folded architecture based on a polarization code is proposed for dynamic optical interconnection. The suggested systems are compact and appropriate for both intracomputer and intercomputer communication. The modularity of the proposed architecture is presented, and a growth rule for the fully connected versions of the system is introduced. The proposed approach significantly reduces both the price of the interconnection systems and their complexity. Presented are 4 x 4 and 8 x 8 fully connected switches, a rearrangeable nonblocking 4 x 4 switch, and a crossbar architecture.

Effects of dead zones in multiple-quantum-well binary-phase modulators on optical interconnections

We investigate the effects of inactive regions [dead zones (DZ's)] in multiple-quantum-well binary-phase modulators used for free-space dynamic optical interconnection applications. Results, however, have implications for other types of pixelated spatial light modulators (SLM's). To our knowledge, the effects of DZ's in SLM's have not before been thoroughly studied in a context other than optical correlation. We investigate the DZ's (considered to be either opaque or transmissive) as a feature that may be exploited in system design, calculating light efficiency and fidelity as a function of DZ fractional width. It is shown that in particular cases an appropriate choice of DZ width would lead to an optical interconnection with substantially improved cross-talk performance.

Dynamic optical interconnection in free-space switching system

Dynamic optical interconnection in free-space switching system

Dynamic optical interconnection in free-space switching system

A dynamic optical interconnection system is experimented by a holographic crossbar. The pixelated multi-phase grating array displayed on spatial light modulator generated a beam array onto an arbitrary position with high efficiency in the output plane. The system operates at high speed as a free-space optical switch.

Nonlinear combinations of gratings in Bi_12SiO_20: theory and experiments

Multiple optical interference patterns generate phase gratings in Bi12SiO20 as a result of the photorefractive effect. Because of the nonlinear response of the space-charge field to the optical interference pattern, these primary gratings interact and cause the formation of additional gratings at frequencies that are combinations of the primary grating frequencies. Only the diffusion regime is considered in the present investigation. In our setup, two primary gratings are induced as the result of interference among one reference and two closely situated object beams. The interference between the two object beams leads to a negligible photorefractive grating, because the photorefractive Bi12SiO20 crystal cannot respond to the corresponding large fringe spacing. We show theoretically that nonlinear combinations of gratings are introduced through this third interference pattern even though the corresponding grating itself is absent. We obtain analytical expressions for the fundamental frequency components of the space-charge field in the special case of a weak reference beam. In the general case, the frequency components of the space-charge field are calculated numerically by the use of Fourier transforms and are incorporated into the coupled-wave equations. The optical beam propagation method is then used for solving these equations numerically. The effect is probed in a three-wave mixing experiment that uses a sinusoidal phase modulation on one of the object beams to control the grating strength. With this technique one of the gratings is specifically canceled out, and the relative change of the diffraction efficiency in the remaining grating is measured. It is shown that nonlinear combinations of gratings may cause relative changes of more than 35% in the diffraction efficiency. The theoretical predictions are in excellent agreement with our experimental results and the cross talk observed in dynamic optical interconnects.

Real-Time Reconfigurable Interconnections for Parallel Optical Processing

In this letter we describe the advantages of a dynamic optical interconnection system for parallel information processing applications. The system is based on a liquid crystal television which acts as a binary phase-only spatial light modulator. We describe example algorithms where reconfigurable interconnects would be useful and present results of several interconnection topologies which have been implemented.

Crosstalk in dynamic optical interconnects in photorefractive crystals

We have investigated the crosstalk between two neighboring gratings in photorefractive Bi12SiO20 optical interconnects. The gratings are induced by the interference between one reference beam and two object beams. By applying a suitable phase shift in one of the object beams, we can selectively switch off one of the gratings. The crosstalk between the two gratings is experimentally determined from the diffraction efficiency in the remaining grating before and after applying the phase shift. The magnitude of the crosstalk is determined by the intensity ratio between the reference beam intensity and the object beam intensity. Crosstalk can be avoided by choosing a certain intensity ratio between the reference and the object beams.

Reconfigurable optical interconnects by a combined computer-generated hologram and spatial light modulator method

A new method for implementing electrically addressed dynamic optical interconnects is presented. In this approach a phase spatial light modulator (SLM) is combined with a computer-generated hologram (CGH). The phase SLM is used to change the phase of the wave front that illuminates the CGH. Binary orthogonal phase codes are used to address the SLM. The CGH is designed with iterative discrete on-axis encoding so that different wave fronts direct light to different locations. High efficiency can be achieved because of the large number and the small dimensions of pixels in the CGH. The dynamic aspects result from the use of an SLM that may have a relatively small number of relatively large pixels. In this manner a high-efficiency programmable interconnect system with fast reconfiguration time based on current technology devices may be implemented. The CGH-SLM method yields connection efficiencies significantly higher than previous methods that are based on the use of thin optical elements. Simulation results indicate that for switch sizes in the range from 1 × 2 to 1 × 8, connection efficiencies of higher than 1/ √N (where N is the number of possible destinations) are feasible.

Dynamic optical interconnects

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text L. Hesselink, "Dynamic optical interconnects," Optics News 15(12), 44-45 (1989) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Photorefractive dynamic optical interconnects

We present and demonstrate a set of dynamic optical interconnects which are based on the double phase conjugate mirror with photorefractive wave mixing. These devices are bidirectional, self-adjusting, and controllable in real time. Uses in various interconnection modes are given.

Dynamic optical interconnects: volume holograms as optical two-port operators

We view a real-time volume holographic medium as a programmable two-port device that operates on an optical electric field. A photorefractive two-port operator can be used to establish the interconnects required by neural network models. The index grating that forms in the medium serves to fully interconnect two layers of processing units and at the same time sums the input signals to the output layer. The dynamics of grating formation in photorefractive media are used to indicate the time evolution of the two-port operator when the diffraction efficiency of the medium is small. We experimentally demonstrate a projection operator whereby we store and recall, in iron-doped lithium niobate, seven 1-D images. The image storage is done without the usual angle or spatial encoding of reference beams. A projection operator is used to recognize what features of an input belong to a space defined by a set of stored vectors. The two-port operator can also be used to perform the complementary function: to recognize what features of an input do not belong to this space.