Month: October 2021

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.