Distributed-Feedback Lasers (DFB)

What Is a Distributed Feedback Laser?

A Distributed-feedback (DFB) laser is a semiconductor source of coherent light, whose active region includes periodic changes in the effective refractive index along the cavity. This periodic structure is the basis of the distributed Bragg reflector (DBR) – the main feature of DFB lasers. It allows obtaining predominantly single-mode operation with high stability and narrow optical spectral linewidth.
The DBR inside the laser functions as a wavelength filter. It passes the target mode and suppresses others. As a result, DFB lasers operate in a predominantly single longitudinal mode at a certain wavelength, making them an optimal choice for various applications, including telecommunication systems, spectroscopic research, and various sensors.
Innolume’s DFB laser diodes operate in part of the near-infrared (NIR) range. This wavelength range (780-1330nm) suited for optical communications, industrial sensors, quality control devices, scientific equipment, and other modern photonic systems.

Benefits of DFB Lasers Over Other Types of Lasers

A distributed feedback laser has high spectral purity, stable operating characteristics, and its wavelength can be precisely adjusted for use in specific technical processes. Its key advantages over other devices include:

Single-mode operation. A single longitudinal mode at a required wavelength, making them a good choice for various applications.

Stable operation. These devices are the most stable laser sources, certain devices can provide mode-hop-free performance over the wide current and temperature ranges.

Narrow linewidth. DFB lasers can achieve a very narrow linewidth, down to hundreds of kilohertz (in some special cases, down to a few kilohertz). This ensures a high coherence length.   

High temperature stability. High wavelength temperature stability, which is several times better than FP lasers (e.g. 100 pm/K vs 300-600 pm/K).

High-frequency. DFB lasers are widely used in high-frequency applications, some of them are capable of direct modulation at frequencies exceeding 10 GHz.

Types of Our DFB Lasers

Distributed feedback laser diodes can differ in configuration and other technical features, making them possible to adapt them to specific applications and technical requirements. Innolume provides a range of popular device options, including:

• Single-wavelength DFB lasers (standard). Distributed feedback lasers with a narrow spectral optical linewidth at a specific wavelength. Stable emission with high coherence length makes them indispensable for telecommunications, spectroscopy, and metrology. Integrated optical isolator is highly recommended for linewidth stability.
• Multi-wavelength DFB arrays (custom R&D). This type is available upon specific customer request.
• High-power DFB lasers. Retain a single-mode operation with a significant increase in power compared to low-power models (< 50mW). Suitable for free-space optical communication and material processing. They are used as pumping sources for nonlinear optics.
• Narrow-linewidth DFB lasers. DFB lasers with an ultra-narrow linewidth (down to 150kHz). This design is optimized for applications where a high degree of coherence is required. These state-of-the-art devices are designed for spectroscopy, quantum optics, coherent communication, optical metrology, LIDAR and even atomic clocks.
• Pulsed DFB lasers. DFB lasers can achieve a peak power of 300mW in nanosecond pulses. They are capable to generate ultra-short pulses of 50 picoseconds with a peak power of 250mW using gain switching technology.
• RF-modulated DFB lasers. DFB lasers, assembled in RF modules are designed for high-frequency applications, supporting direct modulation from tens to hundreds of megahertz, with capabilities extending up to several gigahertz. Versions with integrated Bias-T simplify connections by combining RF and DC bias signals. These versatile modules are suitable for a wide range task.

Specifications of Our DFB Laser Diodes

Distributed feedback laser diodes have controlled, stable characteristics that make them effective in many applications. Their performance is determined by the following parameters:

• Wavelength range: 780-1330 nm for the near-infrared (NIR).
• Temperature-current tunability. DFB lasers are slightly tunable by current and temperature. The typical wavelength tunability with current is about a few pm/mA, while the temperature dependence is about hundreds of pm/K. The wavelength can be accurately adjusted within the recommended current and temperature ranges.
• Optical output power: up to 100mW, depending on the wavelength and design features.
• Linewidth: down to hundreds of kilohertz (in some special cases, down to a few kilohertz). A narrow spectral line is a distinctive characteristic of DFB diode lasers, which allows them to be used in various industries.

• Sidemode suppression ratio (SMSR): more than 40 dB, with typical values around 50 dB. This level significantly reduces spectral noise, allowing the lasers to be used in single-mode operation even at high power.
• Pulsed Operation & RF Modulation. DFB lasers typically provide up to 300mW peak power in nanosecond pulses. Gain switching technology allows generating 50 ps pulses with typical peak power of 250mW. DFB lasers in RF modules support direct modulation from tens to hundreds of megahertz. Versions with integrated Bias-T simplify electrical connections by combining RF and DC bias signals inside the module.

In terms of form factors, distributed-feedback (DFB) lasers are available in TO-can, 14-pin butterfly (type 1), 7-pin RF, and chip-on-submount formats. This makes them versatile and flexible, allowing their use in various photonic systems.

Advantages of Our Distributed-Feedback (DFB) Lasers

Innolume's DFB laser diodes have an optimized design developed through years of work with semiconductor lasers. Our key advantages are wide range of available wavelengths, wavelength precision, narrow linewidth, customized solutions. Below are some of the advantages these devices provide:

• High signal purity in single-mode operation. A DFB laser is capable of operation in single mode, while more affordable Fabry-Pérot (FP) diodes always emit multiple longitudinal modes. Single mode operation eliminates unwanted spectral noise and mode hopes.
• Narrow spectral linewidth. DFB technology allows achieving single mode lasers with the optical spectral linewidth down to hundreds of kilohertz (in some special cases, down to a few kilohertz). This makes them an ideal choice for industries with high requirements for signal purity, such as coherent optical communication systems and spectroscopy.
• Temperature-stable wavelength. The DFB diode laser has a lower temperature dependence compared to conventional FP lasers. This guarantees accurate measurements in laser rangefinders and industrial sensors, even with temperature variations, as well as clean communication.
• RF modulation. The ability of laser diodes to quickly switch between different power levels allows them to be used in fiber-optic networks. They effectively transmit large amounts of information in a short time with minimal distortion. Additionally, they are used in scientific research (e.g. stimulated Brillouin scattering suppression).
• Long coherence length. A distributed-feedback laser has a long coherence length, making it suitable for interferometry, fiber optic sensors, and precision metrology compared to FP and VCSEL devices.
• Customized solutions. Our catalog includes distributed feedback lasers with wavelengths from 968 to 1330 nm and the possibility of individual customization. They can be used in high-tech industries, such as quantum optics, medical equipment, and laser rangefinders.
• Packaging options. Innolume manufactures laser diodes in TO-can, 14-pin butterfly (type 1), 7-pin RF, and chip-on-submount form factors.

Typical Applications of Our Distributed Feedback Laser Diodes

Our DFB lasers are used across a wide range of applications, from telecommunications and data communications (datacom) to quantum communications and space projects. They are also used in precision measurements, medical diagnostics, and various scientific research fields, such as spectroscopy and gas sensing. Here are the most popular applications for Innolume diodes:

• Optical communication and Datacom — including high-speed data transmission systems, optical modules, and data center communication.
• Quantum technologies — including applications in quantum computing, quantum communication, and random number generation for quantum cryptography.
• Biomedical research — such as fluorescence spectroscopy and photon-based diagnostics and glucose analysis.
• Industrial applications — including laser material processing, precision calibration, picosecond pulse generation, and atomic transition spectroscopy.
• Scientific research — gravitational wave detectors, high-precision experiments, and short pulse generation.
• Sensing and detectors — for fiber-optic sensors, atomic spectroscopy, and frequency conversion in spectroscopy setups.
• LIDAR and remote sensing — including distance measurement, 3D mapping, environmental monitoring, object detection, and autonomous vehicle control.

Why You Should Order Distributed Feedback (DFB) Lasers from Innolume

Innolume offers DFB laser diodes with a wide range of available wavelengths, high wavelength stability, narrow optical spectrum linewidth, and customized options. Our lasers are ideal for telecommunications, spectroscopy, LIDAR, and quantum technologies. We offer affordable prices for DFB lasers with different wavelengths, assembled in various housings, suitable for CW, pulsed, and RF applications. This makes it easy to integrate these devices into your systems.

If you are looking for a precise or any additional information, contact us now — our experts will find the perfect solution for your equipment.