Category: FTTX

What is a 980nm polarizer? What are its uses?

A 980nm inline polarizer is an optical component that is used to selectively reflect or transmit light of a particular polarization or convert non-polarized light into polarized light. The most common use for a 980nm inline polarizer is in devices that require high levels of light intensity, such as lasers and fiber-optic communication systems.

What is an inline optical polarizer?

An inline optical polarizer is a device that is used to control the polarization of light. This type of polarizer is designed of small pieces of cable placed in-line with the fiber which ultimately helps in polarizing the light passing through this component.

The inline optical polarizer can be used to control the polarization of light that is transmitted through it. This allows for precise control over the amount of light that is transmitted. The inline optical polarizer can also be used to change the polarization of light. The polarization of light can be changed from horizontal to vertical or vice versa.

How does an inline optical polarizer work?

An inline optical polarizer is a device that is used to control the polarization of light. It can be used to either reflect or transmit light depending on the desired effect. The main purpose of an inline optical polarizer is to create polarized light, which can then be used for various applications such as optical communications, microscopy, and more.

What are the uses of inline optical polarizers?

Inline optical polarizers are specifically designed to allow the light with specific polarization to pass through and block the light with orthogonal polarization. This greatly helps in the conversion of unpolarized light into polarized light with a high extinction ratio.

Some of the most popular uses of optical inline polarizers are:

  • Analysis of polarization
  • Monitoring polarization
  • Control polarization
  • Signal-to-Noise Ratio (SNR) monitoring
  • Polarization mode dispersion monitoring
  • Polarization extinction ratio monitoring
  • Spectrum filtering, monitoring, and control
  • Fiber laser mode-locking
  • Polarization interferometry

What are the applications of inline polarizers?

Since inline polarizers can be used in multiple ways, they are used in a wide range of applications, including:

  • Fiber amplifiers
  • Fiber lasers
  • Fiber sensor
  • Test and measurement
  • Communication systems and more

How to find the best inline polarizers for my application?

To select the most suitable inline polarizers for your application, you need to keep in mind some of the factors mentioned below:

Insertion loss – This is the key factor when buying inline polarizers because it determines the quality of light at the output end. Insertion loss is defined as the loss of light signals while passing through the polarizer. The lower the insertion loss, the higher the quality of life.

Bandwidth – Inline polarizers are available in varying bandwidths for different applications. So, you need to first find out which optical polarizer and fiber can accommodate your specific bandwidth.

Extinction Ratio – The next thing you must note when buying inline polarizers is the extinction ratio. It refers to the ratio of transmission of desired polarization to undesired polarization. Poor ER values can lead to Power Penalty.

Do you need 980nm inline polarizers, 1030nm inline polarizers, 1480nm inline polarizers, or inline polarizers with other specifications? Please connect with DK Photonics.

Why do fiber laser systems need optical isolators?

Optical isolators are passive optical components designed for optical feedback prevention, available with different wavelengths such as 780nm, 800nm, 980nm, 1064nm, and so on. Their wavelength specification helps determine which applications optical isolators are more suitable. For instance, a 780nm optical isolator is best suited for telecommunication applications because 780nm is the wavelength of CD-ROM lasers that can be increasingly used for short-distance data communication.

In this blog, we will discuss why fiber laser systems need optical isolators in detail.

What does feedback do to a fiber laser system?

Even a little feedback can be dangerous for fiber laser systems. As rare-earth doped optical fibers are becoming more popular for designing ultrafast laser systems, certain issues related to fiber-based oscillators and amplifiers are also emerging. A fiber is known to have a high gain medium, which means any light that is unintentionally or accidentally injected into the fiber oscillator or amplifier can adversely affect the system performance significantly. It can lead to instability in the best case and damage in the worst case, and neither of them is good for your fiber laser system.

Optical feedback is produced by back-reflections off of incoming optics or by amplified spontaneous emission from an amplifier. This optical feedback is amplified by a high gain in doped optical fibers, which is harmful to fiber laser systems. Small signal gains of ~20dB or more are more common in optical fibers than a lower gain of ~5dB in bulk-doped materials. This and the relatively smaller size of a beam at the fiber end compared to bulk gain material lead to the damage threshold in fiber systems at lower optical powers.

Hence, it is essential to prevent optical feedback from entering fiber laser oscillators and to safeguard the subsequent amplifiers in fiber laser systems. Fortunately, there is a solution to this problem and that is the use of optical isolators.

How does a Faraday optical isolator ensure feedback prevention in fiber lasers?

A Faraday optical isolator is a special optical passive component that allows the transmission of signal light in only a forward direction and blocks the light coming in a backward direction. The main component of an optical isolator is the Faraday rotator, which is a magneto-optic material. A Faraday rotator’s function is to rotate the plane of polarized light 45 degrees in the forward direction and rotate non-reciprocally an additional 45 degrees in the reverse direction while maintaining the polarization of the linearly polarized light.

When the Faraday rotator is placed between two crossed polarizers, a Faraday optical isolator is formed. This isolator protects laser oscillators and laser amplifiers from the harmful effects of back reflections. A good-quality optical isolator is made of low absorption and high-damage threshold optics and is ideally suitable for use with fiber laser systems.

DK Photonics is the leading supplier of optical isolators in different wavelengths, such as 780nm optical isolators, 980nm optical isolators, 1080nm optical isolators, and more. For any queries related to the order of optical isolators, please connect with us right away.

How Do Fused Fiber Optic Couplers Work?

Fiber optic couplers are a critical component of fiber optic communication systems and networks. They allow two or more fiber optic cables to be connected, as well as split and combine signals. In this blog post, we will discuss how these devices work and their various benefits.

We will also explore the different types of optical fused couplers and when they should be used. By the end of this post, you will have a better understanding of how fused fiber optic couplers work and why they are so useful.

What are Fused Fiber Optic Couplers?

Optical fused couplers are special components used to join two optical fibers together, allowing for the transfer of data. In most cases, these couplers are made from fiber-reinforced plastic (FRP) and feature a small glass window, which is sealed with an adhesive.

Fused fiber optic couplers are an important component in optical communication networks, providing a way to connect two fibers or split a single fiber into multiple fibers. They are used in a variety of industries, including telecommunications, medical imaging, and data centers.

At the most basic level, a fused fiber optic coupler consists of two fibers that are connected together. The two fibers are heated and fused together, forming a single fiber optic connector. The fused connector has multiple channels, which allow light to pass from one fiber to the other.

What are the benefits?

There are several advantages of using fused fiber optic couplers over other types of connectors.

  • They offer superior performance and reliability due to their low insertion loss and return loss. They offer high flexibility and scalability, allowing you to expand your system with additional connections as needed.
  • Furthermore, because fused fiber optic couplers are so durable, they can stand up to extreme temperatures, as well as shock and vibration. This ensures that your connection remains consistent even when faced with challenging environmental conditions.
  • Additionally, these couplers are designed to be low maintenance, requiring minimal upkeep over their long lifespan. This makes them a cost-effective option for businesses looking to optimize their networks.
  • Finally, due to their small size and light weight, they are perfect for applications where space is at a premium, such as in mobile or satellite communications.
  • For these reasons, fused fiber optic couplers can be an ideal choice for businesses seeking to take advantage of the latest in communication technology. They offer a reliable, cost-effective solution that can help ensure smooth and consistent data transmission in any environment

How do they work?

Fused fiber optic couplers are an important component in modern fiber optic communication systems. They are used to connect two or more optical fibers together, allowing them to transmit data simultaneously over a single transmission line.

The fibers are fused together using heat, which creates a strong connection that can last for many years. This type of coupling is widely used in both commercial and military applications.

Optical fused couplers work by allowing light from one fiber to travel through another. The coupling is created when two fibers are heated and then fused together.

As the fibers fuse, their cores become permanently linked, forming a secure and reliable connection between the two. The resulting connection allows data to travel between the two fibers, as well as be transmitted through multiple connected fibers.

Importance and Primary Uses of PM Fiber Components 

When we talk about technology, it’s advancing with time and people are enjoying its benefits. In the list of technologies, one promising option that has been introduced many years ago is PM fiber components. From the time the technology has been introduced, it is being used widely, covering almost every industry. And the wide use of these components has influenced manufacturers to come up with many more advanced components. 

Primary uses of PM fiber components

Primarily, these components are used in communication. The introduction of PM fiber components has revolutionized the efficiency and bandwidth of the conventional communication medium. The components are much faster than the conventional medium, offering better performance in the organization. They are said to be the backbone of the communication industry. 

Other than this, the PM fiber components are widely used in the entertainment industry. They are basically used for optical illusion. As the technology is quite basic, everyone can afford it. You will understand the importance of these components only after using them. 

In the industrial sector, the applications of PM fiber components depend on the need. Just keep in mind that the cost and hassle of using components in a smaller office are minimal compared to a larger office. 

What are the common PM fiber components?

  • Multimode/single mode couplers/taps- It’s a component that provides optical signal splitting while preserving polarization with a high extinction ratio. 
  • Splitters- This component is used to split the signal power transmitted to the element’s input. 
  • Isolators – A component that reduces back reflections in optical fibers and backscattering of light. 
  • Wavelength Division Multiplexers- This component enables the use of multiple light wavelengths and sends data over the same medium. 

Other than these common PM fiber components, there are many more on the list. But, others are used depending on the application requirements. 

Every PM fiber component comes with unique features. It’s not easy for a layman to decide the right uses for these components. So, we recommend you connect with a person who is knowledgeable about the subject and possess the necessary skills. 

How are 125um and 80um PM Fiber Components different?

Discussion about PM fiber components is incomplete without mentioning 125um and 80um PM Fiber Components. These two are the commonly used components. 

Traditionally, 125um PM fiber components were in the picture. But, today, 80um PM Fiber Components are trending and there are many strong reasons for the same. 

The thin diameter of 80um PM Fiber Components has characteristics, such as no tension fused taper, online adjustment of main axes in polarization fibers, and high stability package. The performance of both the components is the same, but 80um offers low bend loss at small bend diameters. 

The 80um PM Fiber Components help users to reduce package sizes significantly, meeting the demands of all current and future applications. 

PM fiber components are important, especially in the communication and entertainment industry. If you belong to any of these industries, look for the right manufacturer of these components. 

What are PM optical components? What are their types?

PM components are some of the most useful micro-optical parts used in a wide range of applications. They are used in a variety of industries, from medical to aerospace, data center to telecommunication, and defense to biomedical, and must meet strict quality standards.

What is a PM Component?

A PM Optical Component is a type of optical component that is designed to do a specific function while maintaining the function of light. These components are made from materials such as glass or plastic and are used in a variety of applications, such as telecommunications, data transmission, fiber lasers, fiber amplifiers, instrumentation, testing, and more.

What are the uses of PM optical components?

PM optical components are used in a variety of applications, from medical devices to telecommunications. They are often used in high-speed data transmission and fiber optic communication systems.

PM components can be used to create a variety of different optical fiber designs, including single-mode and multimode fibers. They can also be used to create bend-insensitive fibers, which are ideal for use in tight spaces or areas with limited access.

In addition to creating fiber communication networks and modifying traditional data transmission networks, PM optical components can also be used in medical devices. They are often used in conjunction with other imaging modalities.

What are the different types of PM optical components?

There are various types of PM components available for a variety of applications. Some of the most important PM optical components are:

  • PM inline polarizer – Available in a wide range of operating wavelengths, a PM inline polarizer is designed to allow light transmission with one specific polarization while blocking other polarization. It can convert non-polarized light into polarized light and is widely used to enhance the extinction ratio of signals with excellent polarization properties.
  • PM isolator – It is a polarization-maintaining fiber optic component designed to pass the light in one direction and eliminate the back reflection and scattering in the reverse direction. It is mainly used for the prevention of optical feedback and o protect the fiber optic systems from damage caused by optical feedback.
  • PM Circulator – It is a small yet high-performance fiber optic component that routes signals from port 1 to port 2 and incoming port 2 signals to port 3, where port 3 signals can either be absorbed if they are unwanted or used if you need a full circulator.
  • PM Filter WDM – This small fiber optic component is used to multiplex PM light signals and maintain the output polarization with a high extinction ratio by employing the latest micro-optic filter technology. It is often available in two variants called PM Filter CWDM and PM Filter DWDM.
  • PM Fused Coupler – This optical coupler made from standard fused PM fiber is designed to split or combine high-power linearly polarized light into two paths or one, respectively, without interfering with other wavelengths used along and perturbing the state of polarization.

Do you need 1.0μm PM components, 2.0μm PM components, or 80μm PM Fiber Components for your project or application? Please connect with DK Photonics.

What is Active/Passive DWDM Mux/Demux?

Before we discuss anything, you need to understand what DWDM technology is. Dense Wavelength Division Multiplexing or DWDM combines a set of optical wavelengths, transmitting with one fiber. As a laser technology, DWDM increases bandwidth on existing fiber-optic backbones. Most importantly, DWDM technology enables optic fiber networks to transmit signals of several wavelengths simultaneously.

The DWDM system has two indispensable modules; Mux and Demux. Together it’s referred to as DWDM Mux/Demux. Mux is at the transmitter end, bringing several data signals together for transporting over a single fiber. On the other hand, Demux, at the receiver end, separates the signals coming together and passing each channel to an optical receiver. 

When combined, the DWDM Mux/Demux multiplexes multiple DWDM channels into one or two fibers, extending the bandwidth of optical communication networks with low cost and long transmission distance. This is what a ideal solution of the model is.

About Active/Passive DWDM Mux?Demux

Based on the device’s need for power supply, the DWDM is divided into active DWDM Mux/Demux and passive DWDM Mux/Demux. If it’s active DWDM Mux/Demux, it means the device needs a power supply. 

Difference

An active DWDM Mux/Demux consists of a wavelength adjustable laser, wavelength-adjustable filter, wavelength-selective amplifier, etc. With this, you get more control over your optical network. The best part is that you can dynamically re-tune wavelengths without dropping connections. Commonly, the active DWDM Mux/Demux is used in large-capacity optical transmission applications. 

On the other hand, passive DWDM Mux/Demux is unpowered, pure optical equipment. Unlike active DWDM Mux/Demux, the passive DWDM Mux/Demux requires zero maintenance, upgrades, or electricity to function properly. It consists of a dispersion device, interference device, optical coupler, etc. Comparatively, passive DWDM Mux/Demux is simple and convenient to use as it is a plug-and-play system, which is mainly applied to the access layer of MAN, campus network, enterprise network as well as various special industry networks, including banking, public, security, etc. In the present situation, it’s widely used in optical fiber communication solutions. 

The only thing is that passive DWDM Mux/Demux doesn’t have OAM, meaning there is no protection in case of link failure. But, fortunately, there is another type of DWDM Mux/Demux to solve this problem. 

This type adds optical switches, optical splitters, and other devices in an optical fiber link based on the passive DWDM Mux/Demux. When power is ON, the third type is used as an active DWDM Mux/Demux to monitor each port in real-time. On the other hand, when the power is off, the device is used as a passive DWDM Mux/Demux without affecting the link transmission. In simple words, the third type combines the advantages of active and passive DWDM Mux/Demux, solving the shortcomings of the passive option. No matter what, it’s difficult to manage and maintain this problem through the intervention of active equipment. 

This is how active and passive DWDM Mux/Demux is different. When you buy them, keep this difference in your mind. 

Difference between CWDM and DWDM Mux/Demux devices

With the advent of big data, organizations need highly efficient and capable data transmission speed. And it has been possible with CWDM and DWDM Mux Demux devices. These technologies can transport an extremely large capacity of data traffic in telecom networks. It’s said that the technologies can easily deal with the bandwidth explosion from the access network.

The only problem with organizations is which device to choose. They are very confused between CWDM and DWDM Mux Demux devices. To make the selection easier, we will discuss the differences between these two devices. But before that, we will discuss CWDM and DWDM technology along with Mux and Demux. 

About CWDM and DWDM technology 

These are two types of wavelength division multiplexing or WDM that solve increasing bandwidth capacity needs. They are specifically designed to tackle different network challenges. 

Coarse Wavelength Division Multiplexing or CWDM technology supports eight wavelengths per fiber and is designed for short-range communications. The technology uses wide-range frequencies with wavelengths spread far apart. 

The cost of CWDM is generally low with a lower capacity of sub-10G and shorter distance applications where cost is an important factor. Compared to DWDM, CWDM supports less capacity of links as well as distance. It’s capable of transporting up to 10 Gigabit Ethernet and 16G Fiber Channel. 

On the other hand, Dense Wavelength Division Multiplexing DWDM uses tighter wavelength spacing to fit more channels onto a single fiber, compared to CWDM. In this, the number of multiplexed channels is much denser. As the DWDM system supports 96 channels spaced 0.8 nm apart, it transmits a huge quantity of data through a single fiber link. 

DWDM systems can carry high amounts of data across long distances spanning up to hundreds or thousands of kilometers. 

About Mux and Demux

Mux or multiplexer combines multiple signals over a channel in the form of a single complex signal. This process is known as multiplexing. In other words, the multiplexing process transmits various digital input signals, analog signals, or streams of data over a single channel, integrating various low-speed channels into high-speed ones for the transmission process. 

On the other hand, Demux works in a reverse manner to the Mux. The process is known as demultiplexing. In this technique, a demultiplexer acts as a combinational circuit, accepting only one data input but directing through various outputs. In other words, demultiplexing reconverts a signal back into its unrelated and separate signals.

Difference between CWDM and DWDM Mux Demux devices

The major difference between CWDM and DWDM Mux Demux devices is the number of channels and ports. 

  • CWDM can have 18 channels but DWDM can have up to 96 channels 
  • CWDM is available in 8 and 16-port models but the common configurations of DWDM are 4,8,16 and 32. 

Though there are only two differences between CWDM and DWDM Mux Demux devices, these differences matter. So, you should choose wisely when you go to buy a DWDM Mux/Demux device and a CWDM Mux/Demux device.

What is the working of single-mode fused couplers?

Fused couplers are one of the most important optical passive components used in fiber optic communication systems. The reason why they are used is that they allow you to do light branching and splitting in passive networks.

These passive components are made by joining two separate optical fibers that work on the principle of coupling between parallel optical waveguides. Their claddings are fused over a small area. In addition to light branching and splitting, fused couplers are also used in various other applications, such as:

  • Wavelength multiplexing or de-multiplexing
  • Filtering
  • Polarization selective splitting
  • Wavelength-independent splitting and more

These components work on the principle of energy transfer between optical fiber cores after fusion.

What are Single Mode Fused Couplers?

The most basic form of a fused coupler is a 2×2 waveguide directional coupler made by placing parallel single-mode optical waveguides. Hence, this type of coupler is commonly called a single-mode fused coupler. Sometimes, this component also represents which fibers it is made of. For instance, a 2.0μm single-mode fused coupler clearly indicates it is made using 2.0μm single-mode fibers.

How do Single Mode Fused Couplers work?

The primary operation of this device involves a complete or partial transfer of optical power between two wavelengths. The transfer of optical power occurs because of the optical coupling between the evanescent tail of one waveguide’s guided mode in which light is launched and that of the natural mode of the second waveguide. You can think of this optical interaction as the beating between symmetric and asymmetric super mode.

An important role in the coupling process is also played by the parallel interaction region, which has a longitudinally constant structure.

As soon as the light is launched into one of the waveguides and it is coupled into one of the waveguides, it excites a linear combination of both types of modes. Since each mode has a different propagation constant, the fields propagating in the system also develop a relative phase difference between the distance of propagation.

When the accumulated phase difference between the two modes over a certain length becomes pi (π), the superposition of both modal fields cancels the field amplitudes in the input waveguide and an addition in the second waveguide. This is referred to as coupled state and the associated interaction length is called coupling length.

When the interaction length extends beyond the coupling length, then reverse coupling occurs and for propagation over double coupling length, there develops a phase difference of 2π. As a result, optical power is restored in the input waveguide. This happens periodically across the entire time of wavelength of propagation.

If both waveguides are identical, there can occur a transfer of complete optical power. However, if both waveguides are non-identical, only a certain amount of maximum power transfer can take place.

At DK Photonics, we manufacture a wide range of fused couplers, including 2.0μm single-mode fused couplers, 1.0μm single-mode fused couplers, 1XN single-mode coupler modules, and more. We also offer customization of single-mode fused couplers. If have any queries related to single-mode fused couplers, please get in touch with us.

What’s the Future of Polarization-maintaining (PM) Components?

PM components are ruling the world. Be it any industry, different types of PM components are widely used, especially in telecommunication. And it’s because of the name but the features and characteristics that PM components have. They work easier, increasing performance and productivity significantly. But, many individuals and business owners are doubtful about the future of PM components. They think it’s just a matter of a year or two and then, things will become like before. Or, something new will come into the market replacing PM components. 

In this post, we will discuss future aspects of PM components. We will discuss if PM components will stay in the market or be replaced by any other component. 

Which market will increase the demand for PM components in the future?

The fiber optic market is competitive and expected to be more competitive. According to a report, the projected growth of the fiber optic market is 10.9% CAGR from 2022 to 2027. 

The factors driving this growth are growing internet penetration and data traffic, the rising number of data center facilities worldwide, and the mounting demand for high bandwidth. 

With the growth in fiber optics, demand for PM components will undoubtedly increase. Not one or two, but every PM component will be in demand, playing crucial roles in the fiber optic market. 

You might not believe this too soon now as the circumstances are not favorable. But, soon after the year 2022, you will find lots of changes in the market and demand for PM components. 

Other things that will contribute to the increasing demand for the PM components 

End users’ demands of performance and reliability of their fiber optic networks increase the use of PM components. Keeping aside everything, these two factors matter a lot. PM components, no matter who the manufacturer, ensure performance and reliability. And this is something end users won’t compromise with, today, tomorrow, or in the future. 

This will keep the demand for PM components stable like today or increase in the future. There will be no decreasing scale for PM components ever. 

Other than this, the customization of PM components will rule the market. Yes, you read it right; customization with PM components. Years ago, manufacturers followed a standard protocol to manufacture PM components, which was not feasible for all industries. But, today manufacturers are offering product customization. They are more responsive regarding individual client needs with issues such as repair and calibration. 

Due to product customization, there has been a huge improvement in the productivity and performance of the industries using PM components. End users are getting what exactly they want without compromising on anything. And this is going to increase in the future as users are happy with customization.  

By now, you might have understood that PM components are not going anywhere. They will strongly rule the market now and forever. So, connect with one of the best PM component manufacturers to fulfill your needs. 

DK Photonics is one name in China that manufactures PM components, including 1.0μm PM Components based on standard and custom specifications. The company offers optical couplers, optical isolators, optical splitters, pump combiners, optical circulators, fused products, WDM and Filter products, high-power PM components, and more. 

Why Do We Need Polarization Maintaining Fibers?

Polarization maintaining fibers has been around since the development of fiber optics in the mid 20th century.

In fact, these fibers are considered to be the next generation of fiber optic technology with capabilities such as high bandwidth, low loss, and high temperature stability.

In order to understand this concept, you must first have an understanding of what polarization is and how it works in fiber optics.

What is Polarization?

Polarization is a fundamental property of electromagnetic waves, which have oscillating electric and magnetic fields. This phenomenon occurs in light waves and radio waves, for example.

Light that is polarized can be described as having an electric field vibrating at right angles to its direction of travel, or an electric field vibrating parallel to its direction of travel.

Light with an uneven distribution of polarization (i.e., light that has both vertical and horizontal components) can be said to be unpolarized.

What is Polarization Maintaining Fibers?

A polarization-maintaining fiber (PM Fiber) is a specialty single-mode fiber. Normally, single-mode fibers can carry randomly polarized light. In contrast, PM fiber propagates a single polarization of light.

Polarization-maintaining fibers maintain linearly-polarized light waves during propagation and do not cross-couple optical power between polarizations.

Some fiber optic components require polarized light input, such as external modulators. This polarization-maintaining feature plays a crucial role in these components.

In order to achieve this characteristic, stresses are induced in the material during the manufacturing process. PMFs come in two types: linear polarization maintaining fibers (LPMFs) and circular polarization maintaining fibers (CPMFs)

Uses of Polarization Maintaining Fibers

A PMF fiber optic cable is used in many applications. In fact, a PMF fiber optic cable might be what you are using to read these words right now!

The most common applications of PMF optical cables include lightwave transmission, telecommunications, and medical equipment.

Many telecommunications companies use PMF optical cables to transmit information over long distances in order to support communication between different countries.

Common medical devices that utilize fiber optics are sonography devices and endoscopes.

Ways of Realizing Polarization-maintaining Fibers

First, a polarization preserving fiber (PPF) has three layers: core, clad, and coating. Inside an optical fiber is a cavity known as core that is surrounded by a cladding.

There are also two polarizations in fiber optics – linear and circular polarization. Circular polarization states that when light propagates through a medium with time-varying ellipticity, its direction rotates continuously around an axis parallel to the propagation direction.

Cross Section of Polarization Maintaining Fibers

Polarization-maintaining fibers (PMF) or polarization-maintaining optical fibers (PMOF) are optical fibers which have a property that preserves the polarization state of light as it travels through them.

This is an important feature for applications in areas such as telecommunications and fiber-optic gyroscopes, and is usually provided by intrinsic material properties (such as birefringence), by inner cladding layers, or by external polarization controllers.

Conclusion

Polarization-maintaining fibers are well known for their ability to allow different polarized components (vertical and horizontal) to be transmitted through the fiber simultaneously. Their applications range from fiber optic sensing to interferometry to slab dielectric waveguides.