Category: Fiber Transceivers

Optical transceivers, Active Optic Cables, data center switches, and cable management in data centers.

PM Optical Circulators: Technology used and Categorization

Since 1990, polarization maintaining optical circulator has become one of the essential components in advanced optical communication systems. Nowadays, its applications have expanded widely not only in telecommunication industry but also in medical and imaging fields. Here, we will discuss this indispensable component in detail. So, let’s start with the basics.

What is a PM Optical Circulator?

PM optical circulator is a three or four port non reciprocal passive component which functions similar to an isolator. It transmits the light wave from one port to next port with maximum intensity while maintaining polarization and blocking any light transmission from one port to the previous port. Thus, it is also featured as a unidirectional circulator.

Technology Used in PM Optical Circulators

Polarization Maintaining Optical Circulators are designed on the basis of nonreciprocal polarization rotation of the Faraday effect. As the working of optical circulators is based on several components such as Faraday rotator, birefringent crystal, waveplate and beam displacer, let’s take a quick look at each of them.

Faraday Effect:

It is a magneto-optical effect which explains the phenomenon in which polarization plane of electromagnetic wave (or light wave) is rotated inside a material under magnetic field applied in parallel to the direction of wave propagation. The unique aspect of this effect is that the direction of rotation is independent of the propagation direction of light wave, which implies that rotation is non-reciprocal.

Light Propagation in Birefringent Crystal:

Birefringent crystal is a common material used in the designing of optical circulators. The crystals used in optical circulators are typically anisotropic uniaxial which means they have two refractive indices with one optical axis. The function of this birefringent crystal depends on the propagation direction of light and its optic axis orientation (crystal cutting). The crystals which are generally used include quartz, rutile, YVO4, etc.

Waveplate:

Also called retardation plate, a waveplate is one of the applications of birefringent crystal. It is made by cutting a crystal into a particular orientation. Due to small birefringence, crystal quartz is broadly used for making waveplates.

Beam Displacer:

A birefringent crystal based beam displacer is used to split an incoming light beam into two beams with orthogonal polarization states.

Categorization of Optical Circulators

Optical circulators are mainly divided into two categories:

Polarization-dependent optical circulator

Polarization-independent optical circulator

The former type is only functional for a light wave with a particular polarization state and is only used in a few applications such as free space communications between satellites and crystal sensing.

On the other hand, the latter type is functionally independent of the polarization state of light. While in ordinary circulators, the polarization is not maintained but there are polarization maintaining optical circulators available in the market also. They are used in a large variety of applications.

According to their functionality, optical circulators can also be divided into two groups.

Full Circulator – light passes through all ports in a full circle

Quasi Circulator – light passes through all ports but the light from last port is lost

Fortunately, due to the advancement in technology, you can avail highly reliable and efficient Polarization Maintaining Optical circulators not only in standard specifications but in customized specifications too.

Things That You Must Know about Polarization Maintaining Optical Circulator

Optical fiber is used for an electric device in which light polarization is required. And each fiber is designed to do a certain job and so is suitable for some certain applications. So you should have the knowledge of an optical fiber that you want to buy and make sure the fiber you want to buy would be perfect for your need. So we have gathered some crucial information about optical circulator used for maintaining light polarization, and that will help you choose the right fiber.

If you are looking for a circulator for devices like fiber amplifiers, fiber sensors, test and measurement appliances, coherent detecting appliances, the 1310nm&1550nm 3-port Polarization Maintaining Optical Circulator with both axis working would be the best choice. The circulator is compact and very efficient to route the incoming signals from Port 1 to Port 2, and incoming Port 2 signals to Port 3. The circulator works as a single that can be used to transmit light from an input fiber to an output fiber. It directs the light returning from the output fiber to the third port. The 3 port circulator with both axis working is like an isolator that protects the input fiber from return power but the light that is rejected can be used.

Another fiber can be also used for those applications is 3 port optic circulator with fast axis blocked. This type of circulator is also lightweight, compact and performs well. This circulator also works as the circulator (with both axis working) does. Both circulators used for maintaining polarization can handle the power ranging from 300mW to 20 W, and have center operating wavelengths ranging from 850nm to 1650nm.

Both optical circulators (with both axis working and with fast axis blocked) provide a host of benefits such as low insertion loss, high isolations, etc. Here are some key benefits that the circulator provides:

Low Insertion Loss

High Isolation

High Extinction Ratio

Low Cost

High Stability & Reliability

Apart from those two circulators that are widely used for a wide range of applications, there are other optical fibers that are used for electric devices. Whatever fiber you buy make sure it works perfectly with your device.

So before you start looking for optical fibers, get to know about your device in details. Learn everything that can help you in a way or so to decide on which type of optic fiber you should look for.

Once you are done with the type of fiber you need, find a Polarization Maintaining Optical Circulator supplier. There are many Polarization Maintaining Optical Circulator suppliers in China, you should trust only those that are reputed and have long been into the business.

Polarization Maintaining Tap Coupler: Features & Major Applications

The polarization maintaining (PM) tap coupler basically provides optical signal splitting with tap ratio while also preserving the exact state of polarization. By combining the PM collimators and thin-film filter technology, the polarization maintaining coupler features high return loss, low insertion loss, environmental stability, and high extinction ratio.

The PM tap coupler splits the light coming from the input PM fiber into two outputs PM fibers. The polarization state further can be aligned with the fast axis or the slow axis of the polarization maintaining fibers. The stainless steel and rugged tap coupler are mainly designed for stability as well as high optical performance. The device with split ratios from 1 to 50% is now available so you can utilize it accordingly to your needs.

Some major applications of polarization maintaining tap coupler:

There are various applications of PM tap coupler, among which the major ones include:

Monitoring signal in polarization maintaining fiber systems

Fiber sensors

Helps in power-sharing of polarization-sensitive devices and systems

Polarization maintaining interferometers

Fiber optic devices and instruments

Coherent detection

Polarization maintaining tap couplers are made of separate crystals of lights and the output port of lights emitted is different from the polarization filter coupler. The coupling ratio is more accurate, while it can also handle high power as compared to the PM filter couplers.

On the other hand, the PM couplers can also be used to split high power linearly polarized light into different paths and that too without disturbing the state of polarization (SOP). Furthermore, it can even be used as a power tap for monitoring the signal power in the PM fiber system that functions without perturbing the linear state of polarization (SOP) of light in the polarization maintaining fiber.

Features of polarization maintaining tap coupler:

Some of the major features of PM tap couplers include:

Low insertion loss

Compact inline package device

High stability power

Can handle high energy and power

The optimum optical performance in a different environment

Excellent credibility

High extinction ratio

Accurate tap ratio

Accurate coupling ratio

So, these are a few primary features and applications of polarization maintaining tap couplers that you must be aware of. Besides, if you have the requirement of this device or any other type of PM coupler with tailored specifications then you may simply talk to PM coupler manufacturers and get the best assistance for the same. Just be sure to consult the right manufacturer so you can be confident that you are investing your money and time on the right device and at the right place.

Relationship Between the Coupler and Splitter

Relationship between the coupler and splitter: In fact, splitter is named for the function of the device, coupler named for its working principle, splitter may be based coupler, and may be based on the waveguide or the separating element, coupler can be done either the splitter, but also can be done WDM, attenuator.

Couplers:

Fiber optic couplers either split optical signals into multiple paths or combine multiple signals on one path. Optical signals are more complex than electrical signals, making optical couplers trickier to design than their electrical counterparts. Like electrical currents, a flow of signal carriers, in this case photons, comprise the optical signal. However, an optical signal does not flow through the receiver to the ground. Rather, at the receiver, a detector absorbs the signal flow. Multiple receivers, connected in a series, would receive no signal past the first receiver which would absorb the entire signal. Thus, multiple parallel optical output ports must divide the signal between the ports, reducing its magnitude. The number of input and output ports, expressed as an N x M configuration, characterizes a coupler. The letter N represents the number of input fibers, and M represents the number of output fibers. Fused couplers can be made in any configuration, but they commonly use multiples of two (2 x 2, 4 x 4, 8 x 8, etc.).

Splitter:

Fiber optic splitter is a device that split the fiber optic light into several parts by a certain ratio. The simplest couplers are fiber optic splitters. These devices possess at least three ports but may have more than 32 for more complex devices. Fiber optic splitters are important passive components used in FTTX networks. But two kinds of fiber splitters are popular used, one is the traditional fused type fiber optic splitter (FBT splitter), which features competitive prices; the other is PLC fiber optic splitter, which is compact size and suit for density applications. Both of them have its advantages to suit for different requirement.

Fiber optic splitter typical parameter include input and output part cable length, splitting ratio, working wavelength and with what kind of fiber optic connectors. Just like fiber patch cable, fiber splitters are usually with 0.9mm, 2mm or 3mm cables. 0.9mm outer diameter cable is mostly used in stainless steel tube package fiber optic splitters, while 2mm and 3mm cables are mostly used in box type package fiber splitters. Based on working wavelength difference there are single window and dual window fiber optic splitters. And there are single mode fiber splitter and multimode fiber splitter. Typical connectors installed on the fiber optic splitters are FC or SC type.

Fiber optic couplers or splitters are available in a selection of styles and sizes to separate or combine light with minimal loss. All couplers are produced employing a proprietary procedure that produces reliable, low-cost devices. They’re rugged and impervious to common high operating temperatures. Couplers can be fabricated with custom fiber lengths or with terminations of any type. For more information about Coupler or Splitter, please contact us at sales@fiber-mart.com.fiber-mart.com is your better choice in fiber splitters.

PLC (Planar Lightwave Circuit) Splitter Module Technology

PLC splitter module technology is the latest in passive, fiber-optic component manufacturing. It uses semiconductor (i.e. integrated circuit) fabrication techniques, to build compact, fiber-optic devices. This technique displaces fused-biconical taper devices for high-count splitters. The resulting devices are smaller and more robust.

Planar lightwave circuit (PLC) splitter is a type of optical power management device that is fabricated using silica optical waveguide technology to distribute optical signals from Central Office (CO) to multiple premise locations. It features small size, high reliability, wide operating wavelength range and good channel-to-channel uniformity, and is widely used in PON networks to realize optical signal power splitting. fiber-mart.com provides whole series of 1xN and 2xN splitter products that are tailored for specific applications. All products meet GR-1209-CORE and GR-1221-CORE requirements.

Couplers and Splitter: Couplers are typically used where an aggregate of optical power is required. Therefore, Coupler Module is an assembly, which houses coupler components. These components combine optical power from two or more inputs. And the splitter applications are more common. Typically, they are used for video distribution or for data network monitoring. Inputs are divided and sent to several destinations (e.g. to neighborhoods for CATV). Alternatively, a low-power signal sample is “read-out” with minimal impact, to the link. Therefore, a Splitter Module is an assembly, which house splitter components. These components divide optical power to two or more outputs.

PLC Splitter is based on Planar Lightwave Circuit technology and precision aligning process, can divide a single/dual optical input(s) into multiple optical outputs uniformly and is denoted 1xN or 2xN. PLC splitter is applied in FTTX developments, PON networks, CATV links and optical signal distribution currently. PLC Splitter offers superior optical performance, high stability and high reliability, meets various application requirements in different environments. The high quality performance such as low insertion loss, low PDL, high return loss and excellent uniformity over a wide wavelength range from 1260 nm to 1620 nm, and work in temperature from -40℃ to +85℃.

PLC based on ion exchange in glass has recently been extended to multimode waveguide structures with large core diameter. Monolithic multimode planar waveguides are now commercially available in form of fiber coupled optical waveguide systems. PLC splitter multimode waveguides are well suited for a variety of applications, especially where complex optical functionality needs to be integrated in a monolithic layout. Thus, compact functional elements with low insertion loss and low wavelength dependant losses can be designed for e.g. spectroscopy, medical science, optical power transfer, sensors, data and signal transfer and many others. Through their compact set-up they are easy to combine with lenses, filters and other micro-optical elements.

fiber-mart.com leader in fiber optic plc splitter, providing a range of fiber splitter, such as bare PLC splitter, PLC splitter with fan out, lockless plc splitter module and PLC splitter box and so on, to meet the needs of a variety Applications of engineering design.

WDM Optical MUX Technology

With the exponential growth in communications, caused largely by the wide acceptance of the Internet, many carriers have found their estimates of fiber needs have been highly underestimated. Although most cables included many spare fibers when installed, this growth has used many of them and new capacity is required. Make use of a number of ways to improve this problem, eventually the WDM has shown more cost effective in most cases.

WDM Definition:

Wave Division Multiplexing (WDM) enables multiple data streams of varying wavelengths (“colors”) to become combined right into a single fiber, significantly enhancing the overall capacity from the fiber. WDM can be used in applications where considerable amounts of traffic are needed over long distance in carrier networks. There’s two types of WDM architectures: Course Wave Division Multiplexing (CWDM) and Dense Wave Division Multiplexing (DWDM).

WDM System Development History:

A WDM system uses a multiplexer in the transmitter to become listed on the signals together, and a demultiplexer at the receiver to separate them apart. With the right type of fiber it is possible to have a device that does both simultaneously, and can work as an optical add-drop multiplexer. The optical filtering devices used have conventionally been etalons (stable solid-state single-frequency Fairy¡§CP¡§|rot interferometers by means of thin-film-coated optical glass).

The idea was first published in 1980, and by 1978 WDM systems appeared to be realized in the laboratory. The first WDM systems combined 3 signals. Modern systems are designed for as much as 160 signals and can thus expand a fundamental 10 Gbit/s system over a single fiber pair to in excess of 1.6 Tbit/s.

WDM systems are well-liked by telecommunications companies because they allow them to expand the capacity of the network without laying more fiber. By utilizing WDM and optical amplifiers, they can accommodate several generations of technology rise in their optical infrastructure without needing to overhaul the backbone network. Capacity of a given link can be expanded by simply upgrades towards the multiplexers and demultiplexers at each end.

This is often made by use of optical-to-electrical-to-optical (O/E/O) translation in the very edge of the transport network, thus permitting interoperation with existing equipment with optical interfaces.

WDM System Technology:

Most WDM systems operate on single-mode fiber optical cables, which have a core diameter of 9 µm. Certain forms of WDM may also be used in multi-mode fiber cables (also referred to as premises cables) which have core diameters of fifty or 62.5 µm.

Early WDM systems were expensive and complicated to operate. However, recent standardization and better understanding of the dynamics of WDM systems make WDM less expensive to deploy.

Optical receivers, as opposed to laser sources, tend to be wideband devices. Therefore the demultiplexer must provide the wavelength selectivity of the receiver in the WDM system.

WDM systems are split into different wavelength patterns, conventional/coarse (CWDM) and dense (DWDM). Conventional WDM systems provide up to 8 channels within the 3rd transmission window (C-Band) of silica fibers around 1550 nm. Dense wavelength division multiplexing (DWDM) uses the same transmission window but with denser channel spacing. Channel plans vary, but a typical system would use 40 channels at 100 GHz spacing or 80 channels with 50 GHz spacing. Some technologies are capable of 12.5 GHz spacing (sometimes called ultra-dense WDM). Such spacing’s are today only achieved by free-space optics technology. New amplification options (Raman amplification) enable the extension of the usable wavelengths towards the L-band, pretty much doubling these numbers.

Coarse wavelength division multiplexing (CWDM) in contrast to conventional WDM and DWDM uses increased channel spacing to allow less sophisticated and thus cheaper transceiver designs. To supply 8 channels on one fiber CWDM uses the whole frequency band between second and third transmission window (1310/1550 nm respectively) including both windows (minimum dispersion window and minimum attenuation window) but the critical area where OH scattering may occur, recommending using OH-free silica fibers in case the wavelengths between second and third transmission window ought to be used. Avoiding this region, the channels 47, 49, 51, 53, 55, 57, 59, 61 remain and these are the most commonly used. Each WDM Optical MUX includes its optical insertion loss and isolation measures of every branch. WDMs are available in several fiber sizes and kinds (250µm fiber, loose tube, 900µm buffer, Ø 3mm cable, simplex fiber optic cable or duplex fiber cable).

WDM, DWDM and CWDM are based on the same idea of using multiple wavelengths of sunshine on one fiber, but differ within the spacing of the wavelengths, quantity of channels, and also the capability to amplify the multiplexed signals within the optical space. EDFA provide an efficient wideband amplification for that C-band, Raman amplification adds a mechanism for amplification in the L-band. For CWDM wideband optical amplification is not available, limiting the optical spans to many tens of kilometers.

Regardless if you are WDM Optical MUX expert or it is your first experience with optical networking technologies, fiber-mart.com products and services are equipped for simplicity of use and operation across all applications. If you want to choose some fiber optic cable to connect the WDM, you are able to make reference to our fiber optic cable specifications. Have any questions, pls contact us.