• Roopal Mundepi

Are Optical Switches (Transistors) The Logical Next Step?


Table of Content


Introduction to Optical Switches

An optical switch, also termed as an optical transistor or a light valve, is a device used to open or close an optical circuit or switch and amplify optical signals. It's a multi-port network bridge that links numerous optical fibers and regulates data packet routing between inputs and outputs. Mechanical, optomechanical, and electronic types are found. While an extra optical source supplies output power, light falling on an optical transistor's input modifies the intensity of light emitted from the transistor's output. An optical switch amplifies the optical signal, since the input signal may be weaker than the source.

Optical switches are used in optical computing and fiber-optic communication networks to control light using nothing but light. Such technology has the potential to outperform electronics in terms of speed while conserving energy.

Features of Optical Switch:

Optical switches have gotten a lot of interest because of these features:

  • The transparency they provide to higher-layer protocol formats. There is no need to know the timing of the incoming data/bits because there is no optoelectronic (OE) conversion and, consequently, no electronic processing of the incoming signal. However, as the demand for higher bandwidths grows, it is evident that current optical networks will be increasingly hampered by the requirement to transform optical data into an electrical form to switch them. Optical regeneration is required for speeds greater than 10 Gbps per wavelength.

  • Cost savings resulting from the avoidance of OE conversion or, if this is not possible, the minimization of OE conversion.

  • When compared to their electrical counterparts, they use less energy and have a smaller footprint.

How Does an Optical Switch Work?

The optical switch is a fiber optic circuit-based device that functions similarly to standard electrical network switches. It guides light from the input to the desired output by moving a mirror (prisms or directional couplers). Mechanical ones physically move fiber or other bulk optic elements. The optomechanical switch, for example, redirected an optical signal by moving fiber via a mechanical device that is commonly powered by a stepper motor.

Types of Optical Switch:

Optical switches are classified as mechanical switches, MEMS (Microelectromechanical System) switches, and other switches based on their fabrication processes and technologies. The first two switch types are currently the most popular on the market. In some situations, thermo-optic switches, electro-optic, and acousto-optics optical switches are employed. Today, we'll concentrate on the two sorts.

Optomechanical Switch: It is the oldest kind of optical switch. However, it was the most commonly used at the time. It is considerably slower due to its operating principle, with switching times in the 10-100 m range. Optomechanical optical switches, in general, collimate beam optics from each input and output fiber and move them around inside the device. As a result, the distance between the input and output fibers can be increased without causing negative consequences, resulting in a lower optical loss. They can, however, attain high levels of reliability, insertion loss, and crosstalk.

Microelectromechanical Systems (MEMS) switches: Because of their adaptability, microelectromechanical systems (MEMS) switches have gotten a lot of attention. Optomechanical switches include MEMS optical switches, which are a subcategory of optomechanical switches. However, the optomechanical switch's features, performance, and reliability concerns are distinct because of the differences in fabrication procedures and its unique microscopic nature. The most obvious disadvantage is that the optomechanical switch is bulkier than other options. However, the MEMS switch addresses this.

The silicon crystal will be etched with several tiny mirrors for the MEMS optical switch. The microarray is rotated by electrostatic or electromagnetic force to change the propagation direction of the input light, enabling the light path to be turned on and off.

Applications of Optical Switches

  • Optical switches have the potential to be used for a variety of applications like improving fiber-optic communication networks' performance. Although data is transferred over fiber-optic cables, functions like signal routing are handled electronically. This usually requires optical-to-electronic-to-optical conversion, which creates bottlenecks.

  • Optical switches grouped into photonic integrated circuits allow for all-optical digital signal processing and routing in theory.

  • The same devices could be used to develop new optical amplifiers that compensate for signal attenuation in transmission lines.

  • The development of an optical digital computer, in which components process photons instead of electrons, is a more advanced application of optical switches.

  • Additionally, single-photon optical switches could be used to address individual units in quantum information processing selectively.

Patent Analysis - Optical Switches

The top ten players in the industry control 18% of the industry's total patents, with a total of 34,599 patents. With almost 1,007 patents in the domain, Nippon Telegraph and Telephone is the company with the most patents. Fujitsu is in second place with 937 patents, while NEC is in third place with 923 patents. With 705 patent applications, Canon is ranked fourth. Panasonic is in fifth place with 586 patents, while Hitachi has 469.

The market coverage area and top 10 markets of the active patent families for optical switches are depicted in the graph below. China has the most patent families, with 4466 patents, followed by the United States with 2605 and Japan with 2283. The surge in optical switches will be focused on these top three regions.

The graph below shows how optical switches have evolved over the last 10 years. Patents for optical switches grew linearly throughout the first half of the decade, but after 2018, there appears to be a decline, which appears to be continuing in the coming years.

Factors such as reduced energy consumption facilitated by optical switches and a surge in demand for high bandwidth & data transmission rates are expected to propel the global optical switches market forward. Furthermore, increased automation across several business verticals, including manufacturing and IT & telecom, contributes to market growth. Budget restrictions and high optical switch costs, on the other hand, are a major restraint on the global optical switches sector.

Can Optical Switches Replace Electrical Transistors?

  • The most surprising discovery was that we could trigger the optical switch with the tiniest amount of light, a single photon, as said by senior author Pavlos Lagoudakis, a physicist at Moscow's Skolkovo Institute of Science and Technology. Electronic transistors that can be switched with a single electron typically require bulky cooling equipment, which consumes power and adds to their operating costs. On the other hand, the new optical switch operates at room temperature.

  • According to scientists in Russia and IBM, a novel optical switch is between 100 and 1,000 times faster than today's leading commercial electronic transistors, and the study could one day lead to a new generation of computers based on light rather than electricity.

  • By switching transistors between one electric state and the other, computers typically express data as ones and zeroes. Photons travel at the speed of light, whereas electrons do not. Optical computers that replace traditional transistors with optical switches might function faster than regular ones.

  • In simple words, the underlying premise is simple: light travels quickly. It is, in fact, the fastest media. As a result, these optical switches' operating input and output are light rather than electricity. Traditional electronic transistors represent either of the binary values - 1 or 0 - by "switching" between these binary states after being forced to do so by a strong enough voltage, the optical switch described by the researchers can switch states with the smallest and most efficient unit of light: a single photon. This results in a switching efficiency that is dozens of times higher than that of electronic transistors.