Basic Knowledge about Optical Switch

Introduction of Optical Switch

Optical switch is an optical device that enables signals to be selectively switched from one circuit to another in optical fibers or integrated optical circuits (IOCs). It is widely used in optical switching, configuration optical add/drop multiplexer(OADM), optical fiber ring protection and optical cross and connection system. It could be divided four types, opto-mechanical optical switch, MEMS optical switch, solid-state fiber optical switch and rackmount & benchtop optical switch. Optical switch is one of the main factors to affect the optical performance of the fiber network. It plays a very important role in the optical network.

optical switch types

Functionality of Optical Switch

The functionality of an optical switch can be described as an optical connection. A connection is the association between two ports on a switch and is indicated as a pair of port identifiers (i, j), where i and j are two ports among which the connection is established. An optical signal could be applied to one of the connected ports. However, the nature of the signal emerging at the other port depends on the optical switch. A connection can be in the on state or the off state. A connection is said to be in the on state if an optical signal applied to one port emerges at the other port with essentially zero loss in optical energy. A connection is said to be in the off state if essentially zero optical energy emerges at the other port.

Connections established in optical switches can be unidirectional or bidirectional. A unidirectional connection only allows optical signal transmission in one direction between the connected ports. A bidirectional connection allows optical signal transmission in both directions over the connection. Connections in passive and transparent optical switches are bidirectional. The same as, if a connection (i, j) is set up, optical transmission is possible from i to j and from j to i.

A passive optical switch does not have optical gain elements, but an active optical switch has optical gain elements. An all-optical switch is a transparent optical switch in which the actuating signal is also optical. Thus an optical signal is used to switch the path another optical signal takes through the optical switch.

Key Features of Optical Switch
  • Compact design
  • Short switching time
  • Low cross talk, Low Insertion Loss
  • Wide operating wavelength Range
  • Highly Stability & Reliability
  • Epoxy-free on optical path
  • Single mode or Multimode optional
Applications of Optical Switch
  • Wavelength selective switches
  • R&D in laboratory
  • Fiber sensor
  • Channel blocking
  • Optical channel monitoring in optical networks
  • Module and System Integration
  • Metropolitan Area Network
  • Network protection and restoration
  • Instrumentation, testing, and measurement

Optical switching technology is driven by the need to provide flexibility in optical network connectivity. With this article, we have learned the basic knowledge of optical switch and known that it is widely used in passive optical network.  In fact, there are more other passive optical components used in passive optical work, such as optical circulator, optical attenuator, and fiber collimator and so on. We will learn one by one in this blog. In addition, if you have any requirements of passive optical components, we welcome you to visit Fiberstore, as it  is a professional supplier in this field.

DO You Know Variable Optical Attenuator?

Optical Attenuator is one part of passive optical components. It’s widely used in fiber optic communications to reduce optical fiber power at a certain level. Variable optical attenuator is one of optical attenuator. Now I would like to introduce some basic knowledge of variable optical attenuator in this blog.

what is Variable Optical Attenuator?

Variable Optical Attenuator (VOA) is a double window (1310/1550nm) of passive optical components. Variable optical attenuator could continually and variably attenuate the light intensity in the optical fiber transmission. Variable optical attenuator cable could help simulate distance or actual attenuation in the fiber optic testing work by inserting a calibrated attenuation into the link. By using the variable optical attenuator (VOA), technicians could verify the power margin received by testing the fiber optic link power budget. Fiber optic VOA can help the user vary the light power injected from a light source into the optical fiber.

VOA type

Principle of Variable Optical Attenuator

The power reduction is done by such means as absorption, reflection, diffusion, scattering, deflection, diffraction, and dispersion, etc. Variable optical attenuator usually works by absorbing the light, like sunglasses absorb the extra light energy. It typically gets a working wavelength range in which they absorb the light energy equally. They should not reflect the light since that could cause unwanted back reflection in the fiber system. Or by scattering the light such as an air gap. Another type of attenuator utilizes a length of high-loss optical fiber. It operates upon its input optical signal power level in such a way that its output signal power level is less than the input level.

Built-in Variable Optical Attenuator

Variable optical attenuator may be either manually or electrically controlled. A manual device is useful for one-time set up a system, and is a near-equivalent to a fixed attenuator, and may be referred to as an “adjustable attenuator”. In contrast, an electrically controlled attenuator can provide adaptive power optimization.

Attributes of merit for electrically controlled devices, include speed of response and avoiding degradation of the transmitted signal. Dynamic range is usually quite restricted, and power feedback may mean that long term stability is a relatively minor issue. Speed of response is a particularly major issue in dynamically reconfigurable systems, where a delay of one millionth of a second can be expected to result in the loss of large amounts of transmitted data. Typical technologies employed for high speed response include LCD, or Lithium niobate devices.

With this blog, we have learnt the basic knowledge of variable optical attenuator.  It is necessary to use in fiber optical communications. Fiberstore is a professional supplier of fiber optic communication solution. Variable optical attenuator is just one of PON(passive optical network) components. For more information about variable optical attenuator, welcome to visit our website or contact us over sales@fiberstore.com.