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How Is Optical Fused WDM Technology Benefiting The Optical Communication Industry?

When two or more optical wavelength signals are combined and transmitted through the same fused fiber core for transferring information, the process is called optical fused WDM, an acronym for Wavelength Division Multiplexing (WDM). In this blog, we will discuss wavelength division multiplexing in brief and see what makes this technology so favorable and popular in today’s time.

An Overview of Wavelength Division Multiplexing

Wavelength Division Multiplexing (WDM) is a technology that is typically applied to wavelength division multiplexers (combiners) and demultiplexers. These combiners and demultiplexers are installed at both ends of a fused optical fiber to combine and split different light waves respectively. The working of both devices revolves around the same principle.

Fused taper, dielectric, raster, and flat are the different types of optical wavelength division multiplexers and their quality is determined by various characteristics such as insertion loss and isolation.

In general, an optical fiber communication line can be divided by using wavelength division multiplexers or demultiplexers. Depending on the number of multiplexing wavelengths, the line can be divided into two-wavelength multiplexers and multiple-wavelength multiplexers. Then, based on the interval between multiplexing wavelengths, it can further be divided into coarse wavelength division multiplexing (CWDM) and dense wavelength division multiplexing (DWDM) that are often used in various WDM systems and optical amplifiers.

How is the optical fused WDM technology beneficial for the optical communication industry?

It allows the full utilization of an optical fiber’s low loss band to maximize an optical fiber’s transmission capacity.
It helps increase the physical limit of information transmission via one optical fiber by two times.
Today, we use only a small part of the optical loss spectrum. The WDM technology can help us make full use of a huge bandwidth of a single-mode optical fiber.
It is empowered with the ability to transmit two or more unsynchronized signals in the same optical fiber and thus, provides compatibility between digital and analog signals. This ability is independent of the data rate, modulation mode, or allows it to remove or join channels even in the middle of the line.
WDM technology can be used for the cables that have already been built with few cores and laid early because it ensures the compatibility to make the transmission of multiple one-way or two-way signals possible.
It helps reduce the amount of optical fiber used and requires fewer fibers to install for a project when compared to old projects before the advent of WDM technology. Thus, it lowers the cost of construction and installation significantly.
Since WDM technology has reduced the number of optical fibers required for a project, it has become easier and faster to recover from a fault.
The sharing of active optical equipment also reduces the cost of transmitting multiple signals or appending new services.
This technology has also reduced the number of active devices used, and hence, also improved the reliability of a system.

With the rising need for the development of integrated cable television services, the demand for increased network bandwidth and optical fused WDM devices is also increasing. What we are facing ahead is the age of optical communication. Thus, there is no doubt that the use of WDM technology will become more common in the future than now.

What Ports Are Available with CWDM Mux/Demux? What Use Do They Have?

CWDM Mux/Demux is a high-end device that enhances the capacity of the CWDM network. Here, CWDM is an acronym for Coarse Wave Division Multiplexing. One simple example of such a device is 4 CH CWDM Mux/Demux. It means 4-channel mux and 4-channel demux integrated into a single housing (which is usually ABS box), and it can combine or separate up to 4 channels with a 20nm spacing.

You can implement CWDM Mux/Demux devices in various analog and digital transmission systems, metro enterprise, cable TV, 3G Telephony, Datacomm WAN, Metro Core, Metro Access, and sensor applications.

When implementing CWDM Mux/Demux, you will find various types of ports. In this blog, we will define these ports and their use in brief so that you have an idea what these ports do when installing CWDM Mux/Demux devices.

Basic Ports That You Will Find on Any CWDM Mux/Demux

Line Port

Also known as the common port, a line port is a must for any CWDM Mux/Demux device. In some devices, there are single fiber line ports, while others have double fiber line ports. The selection of line ports depends on which WDM wavelengths are being used.

A dual-fiber line Mux/Demux employs the same wavelength for two-way transmission. Meaning, each transmitting and receiving port of every duplex channel port uses the same wavelength.

On the other hand, in a single-fiber Mux/Demux, the transmitting and receiving port of every duplex uses two different wavelengths and all wavelengths flow in only one direction.

Channel Port

Another must-have port in a CWDM Mux/Demux is a channel port that sends and receives signals of selected WDM wavelengths. For instance, CWDM technology supports 18 wavelengths that range from 1270nm to 1610nm with the channel spacing of 20nm. Hence, the channel port count in a CWDM device always varies from 2 to 18 channels.

However, in DWDM technology, wavelengths ranging from 1470nm to 1625nm have a channel space of 0.8nm or 0.4nm. As a result, a DWDM Mux/Demux can support more wavelengths and have channel ports from 4 to 96.

Function Ports on a CWDM Mux/Demux That Can Be Added for Enhanced Functionality

Expansion Port

This port is added so that one can add more wavelengths or channels into the existing network. In other words, if you’ve installed a 4CH CWDM Mux/Demux, you can use an expansion port to extend the network capacity. All you need is to connect this port to the line port of another CWDM Mux/Demux to support different wavelengths.

Monitor Port

Today’s CWDM Mux/Demux devices also come with monitor ports to help ensure better network monitoring and management. It allows you to easily test the dB level of a signal without interrupting the service.

1310nm Port and 1550nm Port

In general, in WDM Mux/Demux, channel ports can be connected to color-coded transceivers only. However, with these special ports, the signal that runs through fiber optic transceivers and transmits over 1310/1550nm ports can also be combined with other CWDM devices.

Each port available on CWDM Mux/Demux has a special usage, and therefore, knowing about their functioning and usage can be very helpful in creating a powerful CWDM network.

It is important to note that the same types of ports with the same purposes are also available on DWDM Mux/Demux.

What Is An Optical Fused Coupler? How Does It Work?

A fiber optic coupler is an optical component that is widely used for distributing optical signals over the network. It is designed to distribute signals from one fiber to two or more fibers. In general, optical signals are attenuated more when used in an optical coupler. It is because of the fact that the input signal is not transmitted from one fiber to another directly but divided among different output ports.

When it comes to defining an optical fused coupler specifically, it is important to understand that it is made of two parallel optical fibers that are twisted, stretched, and fused together to ensure that their cores stay in close proximity.

How does an optical fused coupler work?

The intensity profile of optical signals traveling in a single mode (SM) fiber is said to be Gaussian. Meaning, the intensity of light is greatest at the center and tapers off as the core or cladding interface ends. The rear ends of the Gaussian profile slightly goes further across the core and into the cladding. This extended tail at both ends is known as an evanescent wave.

In an optical fused coupler, the cores of two identical parallel fibers are so close that the evanescent wave can leak from one fiber core to the core of another fiber. This, in turn, allows an exchange of energy which is similar to the energy exchange that takes place in two coupled pendulums.

The amount of energy that gets exchanged varies depending on the closeness of two fused cores and the length over which energy exchange occurs. If the coupling length is long enough, complete energy may transfer from one core to another. If the length is even longer, the process will continue, transferring the energy back into the original core. Hence, with the selection of proper length over which energy exchange occurs, manufacturers can achieve any given power transfer ratio.

When the light is launched into an input port during the manufacturing process of a fused optical coupler, the output power that comes out of each output port is rigorously monitored. When the desired coupling ratio is achieved, the fully automated manufacturing process is also stopped. This results in a coupler made of one fiber with two cores that lie very close to each other. This process is called the Fused Biconical Taper (FBT) process.

Depending on the type of optical fused coupler, it is used in a variety of applications, such as CATV systems, optical fiber communication systems, testing instruments, FTTH and LAN optical networks, digital, hybrid, and AM-video systems, fiber sensors, mini EDFA, and small transmitter/receiver modules.

Are You Hesitant In Implementing WDM in Your Next Project? Know Why You Shouldn’t

Years ago, implementing WDM or wavelength division multiplexing in a telecommunication project was a huge task. And it’s because this technique required large, complex systems for proper functioning. Also, the systems were expensive. But today, things are different.

You will WDM with different configurations that are suitable for enterprises, data centers, government operators, and large-scale service providers. Most importantly, the available configurations are cost-effective.

There are many other things to know about WDM that can help your project in running smoothly. In this post, we will discuss some basics and important facts about WDM.

About Wave Division Multiplexing (WDM)

WDM functions by transporting different data streams through one strand of fiber. The transportation is done via differing light wavelengths. As compared to the single beam of light used to transport one data stream, on one wavelength, you will find lots of differences and improvements with WDM. There is no interference between the streams because multiple streams of data can be sent over the same fiber by assigning each data stream its wavelength.

With WDM, you can send data streams over independent channels while allowing for expansion and the addition of more channels.

The two categories of wave division multiplexing (WDM)

Coarse wave division multiplexing or CWDM
Dense wave division multiplexing or DWDM

The two categories of WDM are effective in increasing bandwidth capacity. Somewhat, these categories play a similar role in the implementation of WDM in a project. But, these categories have different channel configurations and have different advantages and disadvantages. The configurations depend on the environment CWDM and DWDM are used and the network challenges they face in the functioning.

Difference between CWDM and DWDM

The CWDM has a lower density with a shorter reach compared to DWDM. CWDM is used at a stretch of up to 80km or less where lower capacity isn’t an issue. On the other hand, DWDM provides higher density, higher bandwidth, and more accurate lasers. DWDM can be amplified to give a much longer reach but at a higher cost and technical complexity. DWDM possibly fits 40, 80, or up to 96 channels on the same fiber pair, which enables a huge amount of data to be pushed through the higher number of wavelengths available.

Working of wave division multiplexing (WDM) transceiver

WDM transceiver converts electrical signals from host equipment into optical signals to be transmitted via fiber. The conversion of the fiber is into a specific light wavelength with a unique color. You can add new channels without affecting existing traffic and transport a mix of data at different speeds over a single fiber of fiber pair simultaneously. The overall working of the WDM transceiver will depend on the selection of the CWDM or DWDM. They should match your multiplexer.

One major advantage of wave division multiplexing (WDM)

Scalability and flexibility- As an operator, you can divide and dedicate channels between many customers along with the organizations. It is easy to divide channels between departments and cope with the increased number of applicants with WDM. Most importantly, video and big data processing are clear.

After reading the post, we hope you won’t hesitate in implementing WDM in your next project.

Some Important Things to Know If Working With Laser Diodes

In today’s world, laser diodes are significantly used. They are used on the large scale as well on the small scale. And it’s all because the laser diodes are versatile, offering a wide of structures for industrial uses.

How do laser diodes operate?

The laser diodes are very similar to lighting-emitting diodes or LEDs. These diodes have an active medium semiconductor.

The laser diodes emit light in continuous wave mode from anywhere from several watts down to just mill watts of power. Talking about industrial diodes, they lack the ability to be overdriven and even small periods of exceeding the maximum power. The exceeding of the power causes damage to laser resonators and effectively shuts down the laser. For industrial purposes, pulsed laser diodes are a good option. They can overdrive effectively and easily for short periods. This is possible with short pulses that are followed by pauses.

To enhance the performance of the laser diodes, many components or parts are used such as pump laser protectors.

What are the uses of laser diodes?

Industrially, small-sized laser diodes are used in laser printers, bar code scanners, laser pointers, and CD planners. On the other hand, the large-sized laser diodes are in defense applications such as the pulsed laser rangefinders in military tanks. Also, in defense, the larger varieties of laser diodes as directed energy strike systems that produce powerful lights to destroy land mines, rockets, mortar rounds, and other ordinances.

In the medical department, the laser diodes or the technology in cosmetic applications such as Intense Pulsed Light for hair, age spots, and wrinkle removal. Also, laser diode technology is used for cavity removal and tooth whitening in dentistry.

Other than this, the application of laser diodes is used in welding and cutting of metals and other industrial materials, fiber optics for telecommunication systems, laser level for surveying, and for taking accurate 3D measurements.

What should you keep in mind while working with laser diodes?

Before you start working, you should know the classification of your laser and the necessary precautions to prevent direct or indirect laser light. If the intensity of the lasers is high, it will be hazardous to your eye and skin. It will burn the retina of the eye as well as the upper layer of the skin severely.

Working with laser diodes can be dangerous to your naked eyes, so you should use protective eyewear like laser goggles. Other than the eyewear, you should use safety equipment “laser-active” signs, door interlocks, and switches.

Laser diodes are useful and applied differently for different reasons and on different platforms. You just have to work with them cautiously.

What is Wavelength Division Multiplexing (WDM)? What is its purpose?

WDM is an acronym for wavelength division multiplexing, a technique that allows modulating different data streams of varying wavelengths onto a single optical fiber. Many consider WDM similar to FDM (frequency division multiplexing); however, they are different from each other. While WDM is carried out in the infrared (IR) portion of the electromagnetic spectrum, FDM takes place at radio frequencies (RF).

In WDM, each infrared channel transmits different radio frequency signals that are multiplexed through frequency division multiplexing or time-division multiplexing. Each multiplexed infrared channel is then demultiplexed and original signals are obtained at the destination. This way, it helps transmit data in different formats and at different speeds on a single fiber at the same time in each channel. As a result, you can enjoy enhanced network capacity while being cost-effective.

What is the purpose of using PM Filter WDM?

Polarization-maintaining filter wavelength division multiplexer, in short, PM Filter WDM, is the technology that helps maintain signal polarization while doing everything that a WDM device does, i.e. wavelength division multiplexing.

PM filter WDM helps facilitate bi-directional communication and boost signal capacity. As wavelength and frequency have related to each other inversely (the shorter the wavelength the higher the frequency), both use the same technology in them. On the receiving end, wavelength-sensitive filters are used.

In simple words, WDM systems can multiplex (combine) signals and then demultiplex (split) them at the final point. They are widely used by telecommunication companies and in various other applications because they allow engineers to expand the network capacity without laying more fibers.

Typically, WDM systems use single-mode (SM) optical fiber which carries only a single ray of light. However, other systems use multi-mode (MM) fiber cable.

Modern systems can handle up to 160 signals and can expand a basic 100 Gbps fiber system to a capacity of more than 16Tbps. You can find even a system of 320 channels. Hence, they find their exclusive application in optical fiber communication to send data in several channels with slight changes in wavelength. With WDM, you can increase the total bit rate of point-to-point systems while maintaining polarization. If we talk about PM Filter WDM specifically, they are mostly used to maintain polarized fiber amplifiers, DWDM networks, and instrumentation systems.

Apart from this, there are various benefits of using WDM technology. Some of these are:

It multiplies the effective bandwidth and, thereby, increases the capacity of a fiber optic communication system.
It reduces the overall cost and enhances the capacity of a cable that carries data.
It has resulted in more efficient modern communication systems that can handle more challenges effectively.

While you can simply use a WDM for enhancing the capacity of a telecommunication network, you will need PM filter WDM when it comes to multiplexing polarized signals so that the polarization of signals remains maintained throughout the operation and network.

What are Faraday Rotators and Isolators in Optical Fiber Communication?

Faraday rotators and isolators are key components of an optical fiber system when it comes to transmitting light signals in different polarized states. The polarized state of a light signal is an important characteristic you need to focus on for effective signal transmission. Optical engineers use a high-power Faraday rotator and isolator to take care of it during the system design. In this post, we will discuss both the products and their application in optical systems.

Faraday Rotator

Faraday rotator is a magneto-optic device that uses the Faraday Effect to rotate the polarization state of transmitted light. The light signal travels through a transparent medium exposed to a magnetic field to change the polarization state. The direction of the magnetic field is either the same as the direction of the transmitted light or opposite to it.

When a light signal passes through a Faraday rotator, its polarization state is continuously rotated through the medium. Every change in polarizations state adds up instead of canceling. This phenomenon is known as non-reciprocal behavior, which makes Faraday rotator distinct from arrangements like waveplates and polarizers.

Applications of Faraday Rotators

Faraday Rotators are most widely used in optical laser applications. Some of the most common applications are:
To protect lasers and amplifiers from back-reflected light.
To introduce round-trip losses in ring laser resonators to enforce unidirectional operation. High-power Faraday rotators are capable of facilitating very small rotation angles as per specific requirements.
Faraday rotators can be used in Faraday mirrors and interferometers.

Faraday Isolators

It is a typical optical isolator used in optical system designs to transmit light signals in specific directions. It also blocks the reflected light in the opposite direction. There are mainly two types of faraday isolators available – Polarization Sensitive Faraday Isolators and Polarization Insensitive Faraday Isolators used for specific purposes.

Applications of Faraday Isolators

Like the Faraday rotators, faraday isolators are also used to protect amplifiers and lasers from back-reflected light. You can use several isolators in amplifier chains between different stages to achieve spontaneous emission.
Faraday isolators are used within a laser resonator to enforce a linear polarization state.
Faraday isolators are also used for mode-locking with polarization rotation in an optical fiber system.

High-power Faraday Rotator and Isolator are used for a variety of applications in a wide range of industries including telecommunication, instrument, automation, and electronics. At DK Photonics, you can purchase high-power Faraday rotators and isolators with standard settings and specifications. You can contact us for custom fiber solutions to meet your specific requirements if you don’t find a standard Faraday rotator or isolator in our catalog.

What Are the Different Uses of Polarization Maintaining Optical Isolators?

Optical reflection is a significant cause of the performance degradation in fiber lasers and amplifiers. This issue can easily be resolved by the use of optical isolators. An optical isolator is a small device designed to transmit optical signals in one direction. It comes in two versions: polarization maintaining optical isolators and polarization insensitive optical isolators.

While both types of optical isolators block any returning light, the insertion loss in a polarization maintaining optical isolator depends on the input polarization.

Polarization Maintaining (PM) Optical Isolators

Polarization Maintaining (PM) optical isolators are simpler and very compact in design and highly suitable for polarization maintaining fiber applications. They are also used in scenarios where an input free space beam of constant polarization passes across the Faraday optics. In both types of applications, the linearly polarized beam from the source is aligned with the transmission axis of an optical isolator.

While most passive optical components are reciprocal, optical isolators are usually non-reciprocal. Meaning, optical isolators allow an optical beam to pass in the forward direction with minimal losses while preventing it to propagate in the backward direction.

Though different types of optical isolators can be found in the market such as all-fiber isolators, fiber-embedded isolators, fiber Faraday rotator isolators, and waveguide-based isolators, the core a typical commercially available optical isolator consists of a Faraday rotator with 45-degree rotation and a pair of birefringent crystals.

Applications of PM Optical Isolators

PM optical isolators are playing an increasingly important role, especially in modern optical transmission systems and fiber optic systems. They are mainly used in applications that are sensitive to unwanted optical reflections and require polarized light. Even a very low optical reflection can cause a significant increase in laser phase noise, intensity noise, and wavelength stability. Hence, the use of optical isolators in such applications becomes inevitable.

Another crucial application of polarization maintaining optical isolator is distributed-feedback lasers that are widely used in transmission systems. The distributed feedback laser frequency is said to be very sensitive to the reflection coupled back to the laser cavity due to the single-cavity mode. Since the laser gain profile is not flat, the frequency fluctuation also leads to power instability. Hence, it becomes quite essential to achieve isolation from the optical circuitry and its reflection.

In some cases, Fabry-Perot lasers may also require isolation from the system to enhance the power stability. When Fabry-Petro lasers have fewer cavity modes, the need for isolation in the system increases even more.

Besides, PM optical isolators are widely used in telecommunications and other areas such as biotechnology and sensing (such as fiber-optic gyros). Plus, you will also find their extensive usage in other applications such as fiber lasers, fiber amplifiers, and fiber sensors.

Everything to Know About Wavelength Division Multiplexing (WDM)

As the name suggests, the wavelength division multiplexing or WDM technique uses different light wavelengths for its processing. In fiber optic transmission, the WDM technology increases the data-carrying capacity by using multiple light wavelengths. In specific, the technology multiplexes several optical carrier signals onto a single optical fiber, using different laser light wavelengths.

People think WDM technology is new in the industry. And thus, they don’t trust the same. But truly speaking, WDM technology was developed many years ago and has been deployed across global networks. Today, technology is used in one form or another to a significant degree.

Classification of wavelength division multiplexing (WDM)

Coarse wavelength division multiplexing (CWDM) – This is defined by wavelengths, which belong to the International Telecommunication Union (ITU). The wavelengths used in this are from 1270nm to 1610nm within 20nm channel spacing. If compared to dense wavelength division multiplexing (DWDM), the CWDM supports fewer channels. So, it becomes the ideal solution for short-range communications. It’s compact and cost-effective.

Dense wavelength division multiplexing (DWDM) – This is defined by frequencies, which is the member of International Telecommunication Union (ITU). The frequency is usually converted to wavelength for use. DWDM is capable to transport up to 80 channels in the 1550nm region. It allows huge amounts of data to travel in one single network link, so it is ideal for long-haul transmission. It’s tightly packed together.

Differences between CWDM and DWDM

Channel spacing
Transmission distance
Modulation laser
Costs

Applications included in WDM technology

When buying WDM products online or in stores, you will come across many options. To make your purchase easy, we have listed some applications included in WDM technology.

Wavelength multiplexers– Increases bandwidth capacity on existing fibers
WDM filters– Routes specific wavelengths to monitoring equipment
Add/Drop multiplexers– Adds/drops wavelengths along a network route
Aggregation multiplexers– Manages different service providers on the same fiber

Benefits of WDM technology

Transmits and receives high capacity data, which is a ready-made option for high-bandwidth transmissions
Boosts the intensity of optical signals for long-range transmission with the help of Erbium-Doped Fiber Amplifier
Ensures transmission transparency because wavelengths are independent and channels don’t interfere with each other
Allows new channels without disrupting the existing traffic services, making the upgrades easier
Maximizes the utilization of fibers and helps to optimize overall network investments

Where should you buy WDM products?

The WDM technology will work and deliver quality service only if you get the right WDM products. Whether you are planning to buy WDM products online or offline, you should research in-depth. You should look for one of the reputable suppliers of WDM products.

DK Photonics is that one popular name that designs and manufactures high-quality WDM products. The company is headquartered in Shenzhen of China. You can place an order for WDM products online through our website and we will deliver them as early as possible. Our products are cost-effective and we offer the best service in the industry.

1064nm PM Isolator: Applications, Features, and Specifications

Are you looking for a non-reciprocal fiber optic device that allows the flow of optical power in only one direction? Well, if your answer is yes, then you should consider the 1064 polarization-maintaining fiber optic isolator because it prevents reflections in the backward direction. By using PM fibers, you can maintain the 1064 PM optical isolator state of polarization of the light. Today, you can easily find both PM and non-PM types of these 1064nm optical isolators.

Basics of 1064nm PM Isolator:

This PM isolator is based on the non-reciprocal Faraday Effect – a longitudinal magnetic field generates a rounded birefringence that rotates the alignment of the incoming polarization.

Applications of 1064nm PM isolator

The primary application of the 1064nm polarization-maintaining isolator is to protect the transmission of the laser diode from back reflections. That’s because such reflections increase the noise in the system by disrupting the diode’s operation. The 1064nm PM isolator also enhances the steadiness of fiber amplifiers by lessening the chances of reaction, which can cause undesirable oscillation.

Fiber-Coupled 1064nm PM Isolator:

A fiber-coupled 1064nm PM isolator is a device that works like an optical diode. That is, it transmits in one direction while blocking light in the other direction. You can find such isolators in fiber-coupled form – with input and output coupled to single-mode fibers.

The 1064nm PM isolator is generally positioned at the output of the optical source to avert the light reflection from returning to the source. Moreover, Doped Fiber utilizes the 1064nm PM isolators for avoiding an oscillating behavior.

Here are a few features of 1064nm PM Isolators:

Polarization maintaining
Low insertion loss
High isolation and return loss
High reliability and stability

Here are a few Specifications of 1064nm PM Isolator

Center Wavelength (nm) 1064
Operating Wavelength Range (nm) ±5-10
Top Isolation at 23 ℃ (dB) 30-35
Min. Isolation at 23 ℃ (dB) 25-28
Max. Insertion Loss at 23 ℃ (dB) 1.2
Lowest Extinction Ratio at 23 ℃ (dB) >20
Min. Return Loss (Input /Output) (dB) 50
Max. Average Optical Power (W) 0.3~200
Max. Peak Power for ns Pulse (kW) 1~50
Max. Tensile Load (N) 5
Operating Temperature (°C) -5 to +50
Storage Temperature (°C) -10 to +60

Important Things to Note:

The 1064nm PM isolator can be customized, and the above specifications are subject to change.
Unless specified, the slow axis of the fiber is aligned with the key of the PM fiber connector.
Bare fiber doesn’t support the connector’s weight.

You should consider the 1064nm PM isolator if you’re looking for a high-quality passive device that can transmit the optical signals in one direction and block all the undesirable optical reflections.