We present some novel architectures for rearrangeably nonblocking multistage photonic space switches implemented using arrays of Ti:LiNbO_{3} directional couplers. Multistage networks, studied mostly in the electronic domain, are obtained by minimizing the number of 2 × 2 elements needed to implement a switch. Unfortunately, straightforward extensions of these networks to the photonic domain show that the switch size has to be severely limited by the crosstalk in each of the Ti:LiNbO_{3} 2 \times 2 switching elements. Our networks, on the other hand, have a controllable (including almost zero) amount of crosstalk, low optical path loss, and an asymptotically optimal number of directional coupler switches for a given switch size. In addition, the switch has a simple control algorithm and its performance for light loading appears very promising. The switch is easily decomposable into smaller arrays of no more than two types, making it easy to partition the switch into chips. At the cost of a slight increase in crosstalk, the switch can be made single fault tolerant in terms of its ability to connect any input to any output.

https://link.springer.com/content/pdf/10.1007%2F978-3-642-73388-8_29.pdf

Dilated Networks for Photonic Switching

Photonic technologies are reviewed that could become important components of future telecommunication systems. Photonic devices and systems are divided into two classes according to the function they perform. The first class, relational, refers to devices, that map the input channels to the output channels under external control. The second class, logic, perform some type or combination of Boolean logic functions. Some of the strengths and weaknesses of operating in the photonic domain are presented. Relational devices and their applications are discussed. Optical logic devices and their potential applications are reviewed. >

Architectural considerations for photonic switching networks

/pdf/architectural-considerations-for-photonic-switching-networks-1i2x1zt1o2.pdf

The strengths and limitations of the photonic technology are reviewed, beginning with the temporal bandwidth limitations of photonic devices and then focusing on spatial bandwidth, commonly referred to as the parallelism of optics, and how it can be used in photonic fabrics. Some of the proposed photonic switching fabrics that are based on guided-wave devices are discussed, comprising switching fabrics based on space channels, using directional couplers and optical amplifiers, and those based on time channels. The latter include active reconfigurable fabrics based on TDM, time-slot interchangers, and universal time slots, in addition to passive shared media fabrics. Some of the switching fabrics that have been proposed using wavelength channels are outlined, and multidimensional fabrics are briefly reviewed. Photonic switching fabrics based on free-space devices are described, covering free-space relational switching fabrics, the basic hardware required for digital free-space optical fabrics, and digital free-space switching fabrics. >

Photonic switching fabrics

Guided-wave devices demonstrated in lithium niobate have been seen for many years as highly functional components for applications in fields such as optical communications and sensor systems. The potential for their use has been recognized by the substantial research and development effort the technology has witnessed, and the subject matter of this article is born from these endeavours. The material reviewed includes a survey of devices built, including their design, functionality, and performance, as well as parallel activities that have been undertaken in materials processing, theory, and the development of lithium niobate itself, all of which are closely linked, and all of which have played an important part in the overall development of this major branch of contemporary optics research.

https://iopscience.iop.org/article/10.1088/0034-4885/56/3/001/pdf

Lithium niobate integrated optics

Several low crosstalk 4 × 4 crossbar optical switch arrays have been fabricated for use at \lambda = 1.3 \mu m. Each array consists of 16 independently functioning directional coupler switches. We describe the typical device performance characteristics. The average insertion loss is 5.2 dB. Crosstalk levels routinely measured < -35 dB. The voltage required to operate the device is ≈ 13 V. The inputs to one of the device arrays were permanently attached to four laser transmitters using lensed polarization maintaining fiber at the laser end and an array of polarization maintaining fibers at the device end.

E. Murphy

Papers

Low crosstalk 4 × 4 TiLiNbO 3 optical switch with permanently attached polarization maintaining fiber array

E. Murphy

Papers

Low crosstalk 4 &#215; 4 TiLiNbO 3 optical switch with permanently attached polarization maintaining fiber array

Low crosstalk 4 × 4 TiLiNbO 3 optical switch with permanently attached polarization maintaining fiber array