Category: PM Circulator

Polarization Maintaining Optical Circulator Guide 

Polarization maintaining (PM) optical circulators are key components in fiber optic networks and instruments. This guide provides an overview of PM optical circulators, their features, and applications. 

What are PM Optical Circulators? 

A PM optical circulator is a small fiber optic device that directs light signals from one port to the next in only one direction. 

Light entering Port 1 exits from Port 2. Light entering Port 2 is directed to Port 3. The circulator blocks light from traveling in the reverse directions. 

PM circulators maintain the polarization of light signals passing through them. This makes them ideal for use with other PM fiber components. 

Key Features of Polarization Maintaining Optical Circulator 

PM optical circulators come with the following features: 

  • Compact size 
  • High channel isolation – signals stay isolated in directed ports 
  • Low insertion loss – minimal signal loss through device 
  • High extinction ratio – low crosstalk between ports 
  • High stability and reliability 

They are available with various connector types like FC/PC, FC/APC, and no connectors. Center wavelength options include 2000nm, 2050nm, 1940nm, 1550nm, 1310nm, 1064nm, 10130nm, and more. 

Applications 

Common uses of PM optical circulators include: 

DWDM Networks 

Circulators allow individual channels to be dropped/added from dense wavelength division multiplexing (DWDM) networks. 

Fiber Amplifiers 

They enable bidirectional flow in erbium-doped fiber amplifiers and fiber lasers. 

Fiber Sensors 

Circulators route light to and from fiber Bragg grating (FBG) sensors. 

Test Equipment 

Used to route signals in optical test setups and instrumentation. 

Coherent Detection 

Support bidirectional transmission in coherent fiber optic communication. 

How Polarization Maintaining Optical Circulators Work 

PM optical circulators use a non-reciprocal property, meaning light traveling in one direction experiences a different effect than light going the reverse way. 

This breaks the symmetry of the ports, allowing light to pass from ports 1 to 2, but not 2 to 1. Isolation between ports is crucial for proper circulator function. 

Proper alignment of the fiber ports and internal components gives the desired circulation. The non-reciprocal property is typically achieved using a Faraday rotator crystal. 

PM optical circulators provide key routing capabilities for fiber networks and instruments. Their non-reciprocal design, polarization maintaining properties, and bidirectional light control make them an essential component in many photonics applications. 

Advancements in PM Optical Circulator Technology  

With ongoing research and development, PM Optical Circulator manufacturers are introducing new features and capabilities to meet the evolving demands of the industry. Enhanced designs and materials can lead to higher polarization extinction ratios, ensuring minimal polarization crosstalk and maintaining signal integrity in demanding optical systems. 

Developments in packaging and integration enable greater flexibility in system design and deployment. Compact form factors and compatibility with a wide range of connector types facilitate seamless integration into various optical setups and systems.

What is an optical circulator in fiber optics? What is it used for?

An optical circulator is a passive multi-port optical component characterized by its non-reciprocal property. It works by keeping the reflected light from coming back to the source and allows this light to pass through the subsequent port, where this light is either absorbed or used. This component is designed in such a way that the light entering from any port exits from the next port. For instance, if light enters port 1, it passes through port 2 and the reflected light that tends to come back to port 1 does not come out of port 1, but instead, it exits from port 3.

This configuration, which is a form of passive circuit, allows the light to travel in a single direction around the loop while preventing the light from traveling back in the opposite direction. This means that signals are passed from one port to another while they are still being transmitted.

Why an optical circulator is called a non-reciprocal device?

Optical circulators are non-reciprocal optics, which means that changes in the properties of the light passing through the device are not reversed when the light passes through in the opposite direction.

When an optical signal is polarized by the Faraday effect, the polarization is not reciprocal. When an optical signal is input from any port, it can be output from the next port sequentially with very low loss, and the loss from this port to all other ports is very large; hence, these ports do not communicate with each other.

Since these ports do not communicate with each other, they can be used to create a passive star network.

What is an optical circulator used for? What are its applications?

Fiber optic circulators are primarily used to keep the incoming light from source and reflected that travel in opposite directions in an optical fiber separated. As a result, it can also help achieve bi-directional transmission through a single optical fiber.

Optical circulators are widely used in advanced communication systems and fiber-optic sensor applications because they have high isolation of the input and reflected optical powers and a low insertion loss.

How is an optical circulator formed?

A Faraday rotator is a device used to rotate the direction of linear polarization. A Faraday rotator is attached to two polarizing prisms on both sides.

When polarized light passes through a Faraday rotator, its polarization plane can rotate 45° under the action of an external magnetic field. As long as the optical axes of the two polarizing prisms are set at an appropriate angle to each other, the insertion loss of the optical paths can be very little and the isolation of non-connected path is very high.

An optical circulator can also be formed by utilizing the characteristics of single-mode fiber, which will produce the Faraday rotation effect under the action of an external magnetic field.

At DK Photonics, we offer a wide variety of optical circulators, including low-power and high-power circulators. Whether you are looking for 1064nm high power circulators or simple 980nm optical circulators, contact DK Photonics right away.

How is Polarization Maintained?

Light is a form of electromagnetic wave. It is made of electrical and magnetic fields that oscillate. While you can define light and its effects in terms of the magnetic field, it is easy to characterize its qualities by examining its electrical field.

Polarization Maintained

Light waves can vibrate in different directions. Polarized light is a light that vibrates in just one direction — in a single plane, such as up and down. Unpolarized light is a light that vibrates in more than one direction — in more than one plane, such as up/down and left or right.

How to Obtain Single Polarization?

A polarization filter is the most common way to achieve single polarization. These filters are built of unique materials that can block one of an electromagnetic wave’s two vibrational planes.

A polarization filter is a device that filters out half of the vibrations transmitted through a filter as light passes through it. When unpolarized light passes through a polarization filter, it becomes polarized light, which has half the intensity and vibrates in a single plane.

What is Polarization Maintaining Fiber?

A polarization-maintaining fiber (PM Fiber) is a form of single-mode fiber that maintains polarization. Single-mode fibers can convey polarized light that is randomly polarized. However, PM fiber is designed to transmit one polarization of input light.

The polarization of linearly polarized light waves sent into the fiber is maintained throughout propagation in polarization-maintaining fiber, with little or no cross-coupling of optical power between the polarization modes.

This polarization-maintaining characteristic is critical for some fiber optic components that demand polarized light input, such as external modulators. This property is acquired by creating stresses in the material during the production process. Linear polarization-maintaining fiber (LPMF) and circular polarization maintaining fiber (CPMF) are the two types of polarization-maintaining fiber available.

Applications of Polarization Maintaining Fibers

  1. Fiber optic sensing, interferometry, and slab dielectric waveguides are just a few of the applications for PM optical fibers.
  • PM fibers can be used in coherent and long-distance bidirectional optical transmission systems.
  • They can also be employed in transmission applications where the polarization plane of the optical signal is critical, such as optical sensor transmission lines and optical-electrical integrated circuit coupling.
  • PM fibers are used in lithium niobate modulators, Raman amplifiers, and other polarization-sensitive devices to keep the incoming light polarized and minimize cross-coupling between polarization modes.

What Limits the Performance of PM Fibers?

PM fiber guides light in a linearly polarized form from one location to another in the most typical optical fiber telecommunications applications. It is crucial to meet several requirements to attain this result. In order to avoid launching both slow and fast axis modes, the input light must be highly polarized, resulting in an unpredictable output polarization state.

For the same reason, the electric field of the input light must be precisely aligned with a principal axis (the slow axis by industry convention) of the fiber. The rotational alignment of the joining fibers is crucial if the PM fiber line comprises segments of fiber linked by optical connectors or splices.

Lastly, connectors on PM fibers must be positioned in such a way that internal tensions do not allow the electric field to be projected onto the fiber’s undesired axis.

All you need to know about polarization maintaining optical circulators: a few major pointers!!

Since several years, Polarization Maintaining Optical Circulator has become an important element in the optical communication system. But these days, its applications have expanded not only in the telecommunication field but also in imaging and medical field.

In this blog, we’ll discuss on Polarization Maintaining Optical Circulator in more detail, but before that let’s know a few basic regarding it.

To begin with, let’s discuss what exactly is an optical circulator?

An optical circulator is mainly a multiple port non-reciprocal passive component. Its function is just similar to that of a microwave circulator, i.e. to transmit the light wave from one port to other with maximum intensity. But, at the same time, it also blocks any light transmission from one port to its previous port. Besides, the entire optical circulator process is based on the non-reciprocal polarization of the Faraday Effect.

What are the features of Polarization Maintaining Optical Circulator?

There are various features of polarization maintaining optical circulator. Mentioned below are a few major ones:

–    It has a high stability

–    It has a low insertion loss

–    It has high reliability

–    It has high optical return loss and so on.

How can optical circulators be categorized?

Optical circulators typically can be categorized into two main streams namely:

–    Polarization-dependent optical circulator, and

–    Polarization independent optical circulator

Polarization-dependent optical circulator is functional only for a light wave with a specific polarization state. This type of optical circulator is used only in some of the applications that mainly include free space communication between crystal sensing and satellites. Whereas the polarization independent optical circulator is independent of the polarization state of light. In the ordinary circulators, the polarization is certainly not maintained, however, there are polarization maintaining optical circulators available, so they can be used on behalf of it.

Besides, they can also be utilized in a wide variety of applications, but depending on its functionality, optical circulators may be divided into two groups:

–    Quasi circulator: In this circulator, the light passes through all the multiple ports, but the light from the last port is lost.

–    Full circulator: In this circulator, the light passes through all the multiple ports in a full circle.

When it comes to circulator’s design, there are many variations, but, all the non-reciprocal rotation designs certainly share the same structure with at least three functional elements namely- non-reciprocal polarization rotation elements, polarization recombining, and splitting elements, as well as polarization dependent beam steering elements.

Finally, we can say that with the large development of advanced optical networks and elements, the application of optical circulators are rapidly growing and new and advanced applications and functionalities are emerging quickly.

Optical Circulators and Its Passive Optical Components

To fulfill the requirement of communication efficiency, network technicians generally use optical circulator in a fiber optic system as it reduces the loss of light. An optical circulator is a small yet powerful device used in optical communication systems. The device is typically used to separate optical signals that (in an optical fiber) travel in opposite directions.

Functioning Principle and Components

Optical circulators usually consist of a polarizing beam splitter, Faraday rotator, reflector prism, birefringent blocks, and a retardation plate. The functioning of an optical circulator is a little similar to optical isolator. A light which travels in one direction right through the Faraday rotator will have its polarization rotated in one specific direction. A light that enters the rotator from the opposite direction will have its phases rotated in the opposite direction (sometimes may depend upon the propagation direction of the light).

In other words, light always rotates in one direction in accordance with the rotator regardless of its traveling direction.

Three-port optical circulator is widely used so let’s discuss that first. A signal in a three-port optical circulator is transmitted from 1st port to 2nd port where another signal is transmitted from 2nd to 3rd and additionally, a third signal can also be transmitted from 3rd to 1st.

Types

As per the Polarization Characteristics

If we talk about the characteristics based on the optical circulator’s polarization capabilities, they can be divided into two major types:

PM – Polarization Maintaining

PI – Polarization Insensitive

Each PM optical circulator typically comes in the market with a polarization maintaining fiber which makes it an ideal component for applications where it is necessary to maintain polarization, for example, Raman pump applications, 40Gbps systems, etc.

Polarization insensitive optical circulator is a small lightwave component which delivers high-performance functioning. The component comes in the market having features like low insertion loss, high isolation, high stability and reliability, and low polarization-dependent loss (PDL).

It is high in demand in combination with fiber gratings and other reflective components in close-packed wavelength-division multiplexing (DWDM) systems, high-speed systems and bi-direction communication systems.

As per the number of ports availability

Optical circulators fall into three main types when it comes to the number of ports:

3-port

4-port

6-port

3-port and 4-port optical circulators are commonly used way more than the 6-port optical circulations. In such circulators, optical light that is transmitted from any port can easily be redirected to any other port, regardless of the port-type.

An optical circulator is very commonly applied in a long list of applications within a fiber communication system. In modern optical communication systems, the optical circulator is usually used for wavelength division multiplexing networks, optical time domain reflectometers, fiber amplifier systems, bi-directional transmissions, etc.

With primary characteristics such as high isolation, low crosstalk, low insertion loss, and large bandwidth, the optical circulator can also become an in-built component of the same device as transmitters, amplifiers, and receivers.

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.

Everything You Ought to Know about 1064nm High Power Circulator

1064nm High Power Circulator broadens the essential thought behind an optical isolator and adds greater usefulness to the gadget. A circulator does not dispose of the regressive proliferating light, as an isolator does, yet guides it to another port, along these lines bringing about a three-port gadget in the most straightforward design. More ports can be added on the off chance that one needs to divert light originating from the third port to a fourth port. Indeed, even six ports circulators exist which guide light to various ports in a roundabout form contingent upon which port light enters.

You may figure that with the expanding of ports, the outline turns out to be progressively mind-boggling. You are totally right on that figure. The second layer of multifaceted nature is included for polarization-free circulators on the grounds that they should part the approaching light from any port into its symmetrically captivated segments and process every segment independently.

All in all, a circulator requires countless. The most critical part in a polarization autonomous circulator is the bar displacer. Shaft displacer is produced using a firmly birefringent medium with the end goal that it uproots the symmetrically captivated parts spatially by various sums.

Notwithstanding their multifaceted nature, optical circulators are accessible economically in a generally smaller size with fiber braids on each end. Inclusion misfortunes are likewise exceptionally satisfactory for such complex gadgets.

It is vital to observe that before purchasing 1064nm High Power Circulator, you need to ensure the provider truly offers you with quality gadgets. As a business, you generally need to ensure you acquire solid circulators and isolators at a focused cost. By doing your examination, you can discover organizations that have the goal of satisfying if not surpassing your needs and desires.

The provider you ought to lean toward must be focused on giving quality gadgets that your organization can make utilization of for a broadened timeframe. Notwithstanding their great quality line of items, you may likewise need to accentuate the supplier¡¯s amicability when managing clients particularly on the off chance that you have specific needs.

They ought to have proficient staff that will engage any inquiry you may have and each one of those critical things you have to think about the setups and in addition the employment of ferrite isolator. Having the capacity to fabricate long haul association with the provider can be a path for you to ensure that you are getting the greater part of your ventures.

Picking the privilege 1064nm High Power Circulator provider might astound particularly when you locate that the vast majority of them are promising you of value RF isolator and circulator. Research before buy can assume an essential part in guaranteeing that you have picked the correct provider. The web can be an incredible place where you can discover a choice of exceptional providers of the drop-in isolator and drop in the circulator.

In the event that you are uncertain of your choice, dependably make utilization of audits and discussions where you can discover individuals who have acquired these gadgets from specific producers.

Steps to Choose the Best and Effective Polarization Maintaining Optical Circulator

What is polarization?

Light waves comprise of wavering electric and attractive fields. These two fields are opposite to each other and to the course of light voyaging. We call the electric field plane as the light’s polarization.

Daylight and numerous other customary lights are made of numerous light waves, each with their electric and attractive fields situated arbitrarily. On the off chance that all waves’ electric fields were adjusted parallel to each other, we call this light directly captivated.

* Polarization’s impact on optical Circulators

Polarization does not by any means make a difference in multimode strands however it can be critical in single mode Circulators particularly for long separation and fast rate fiber interchanges. Why? Give me a chance to clarify it underneath.

In fact talking, single-mode strands really have two modes going in it. These two modes have symmetrical polarization and immaculate single mode Circulators can’t separate between them. These two modes are practically indistinguishable and light vitality can move effectively between these two polarization modes.

In any case, fiber’s geometry isn’t great. Thus, these two modes really travel along the fiber at marginally extraordinary paces. The impact is called PMD (polarization mode scattering). The slight speed distinction can cause issues in rapid fiber optic connections, for example, 10Gbit/s and 40Gbit/s.

* Polarization keeping up Circulators acts the hero!

Polarization keeping up Circulators are uncommon sorts of single-mode strands, they are likewise normally called PM Circulators or Panda PM Circulators.

PM strands have worked in asymmetry which is likewise called birefringence. The refractive file of PM fiber contrasts for the two polarizations and this impact keep light vitality from coupling between two polarizations.

PM strands can transmit light in a solitary polarization if the info light polarization is adjusted to one of its two birefringence tomahawks. What’s more, that is the reason they are called polarization looking after Circulators.

* The uses of polarization looking after Circulators

PM Circulators are once in a while utilized for long separation transmission in light of their costly cost and higher weakening than single mode fiber. They are regularly utilized for media transmission applications, fiber optic detecting, and interferometer.

What is polarization mode dispersion then?

  1. Polarization mode and polarization mode dispersion (PMD)

In single mode filaments, light heartbeats are really made out of two particular polarization modes. The electric field vector of the two modes is opposite to each other or called symmetrically. Regularly the two polarization modes act only the same in the fiber which implies they can’t be recognized.

Yet, that is just the hypothesis with a flawless symmetrical fiber and no outside power on the fiber. Since the world isn’t flawless nor is the fiber, these two polarization modes do carry on another way in certifiable filaments.

Worries inside the fiber and outside powers connected to the fiber make the refractive record of glass vary marginally for these two polarization modes. This marvel is called birefringence.

Birefringence influences these two polarization modes to movement at marginally extraordinary speed. This speed contrast widens light wave flag similarly as different scatterings and this reality is called Polarization Mode Dispersion (PMD).