Acronym: DFB lasers
Definition: lasers where the whole laser resonator consists of a periodic structure, in which Bragg reflection occurs
More general term: lasers
Categories: optical resonators, optoelectronics, laser devices and laser physics
Author: Dr. Rüdiger Paschotta
Cite the article using its DOI: https://doi.org/10.61835/gdn
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A distributed-feedback laser (DFB laser) is a
laser where the whole resonator consists of a periodic structure in the laser gain medium, which acts as a distributed Bragg reflector in the wavelength range of laser action. Typically, the periodic structure is made with a phase shift in its middle. Essentially, one has a direct concatenation of two Bragg gratings with optical gain within the gratings. The device has multiple axial resonator modes, but there is typically one mode which is favored in terms of losses. (This property is related to the above-mentioned phase shift.) Therefore, single-frequency operation is often easily achieved, despite spatial hole burning due to the standing-wave pattern in the gain medium. Due to the large free spectral range, wavelength tuning without mode hops may be possible over a range of several nanometers. However, the tuning range may not be as large as for a distributed Bragg reflector laser.
Figure 1: DFB fiber laser, containing a fiber Bragg grating with a phase change in the middle, directly written into a rare-earth-doped fiber.
DFB lasers should not be confused with
DBR lasers = distributed Bragg reflector lasers. Types of DFB Lasers
Most distributed-feedback lasers are either
fiber lasers or semiconductor lasers, operating on a single resonator mode (→ ). single-frequency operation Fiber Lasers
In the case of a fiber laser, the distributed reflection occurs in a
fiber Bragg grating, typically with a length of a few millimeters or centimeters. Efficient pump absorption can be achieved only with a high doping concentration of the fiber, and unfortunately it is often not easy to write high contrast Bragg gratings into fibers with a composition (e.g. phosphate glass) which allows for a high doping concentration. Therefore, the output power is usually fairly limited (e.g. to a few tens of milliwatts), and the power conversion efficiency is small. However, this kind of single-frequency fiber laser is very simple and compact. Its compactness and robustness also leads to a low intensity and phase noise level, i.e., also a low linewidth, although the fundamental linewidth limit (the Schawlow–Townes linewidth) is higher than for longer fiber lasers. Diode Lasers
Semiconductor DFB lasers can be built with an integrated grating structure, e.g. a corrugated
waveguide. The grating structure may be produced on top of the active region, which however requires time-consuming regrowth techniques. An alternative is to make laterally coupled structures, where the gratings are on both sides of the active region. Semiconductor DFB lasers are available for emission in different spectral regions at least in the range from 0.8 μm to 2.8 μm.
Typical output powers are some tens of milliwatts. The linewidth is typically a few hundred MHz, and wavelength tuning is often possible over several nanometers. Temperature-stabilized devices, as used e.g. in
DWDM systems, can exhibit a high wavelength stability.
contains RP Photonics Buyer's Guide 44 suppliers for distributed feedback lasers. Among them:
LM – DFB semiconductor laser module from Teraxion is a no-fuss laser module that combines a DFB semiconductor laser diode, a low-noise current source, and a temperature controller, all into a single package. The compact size of the LM does not sacrifice power—the output from an LM can be as high as 100 mW. The LM operates single-mode with a linewidth less than 1 MHz and is tunable over a 50 GHz range with 5 MHz resolution. The compact, high-power, and reliable LM laser comes ready-made for integration in embedded designs and OEM applications.
Laser 1200 Series is a compact and versatile fixed-wavelength laser source that can be customized to meet specific wavelength and power requirements, and is available in benchtop or PXI form factor.
Eblana Photonics core product offerings are based on our patented
Discrete-Mode manufacturing technology, which delivers industry leading performance with fully scalable, consistent production and integration capability. Eblana’s Discrete-Mode laser diodes are used extensively for trace gas sensing, fibre sensing and LIDAR applications and environmental monitoring in the near- and mid-IR (650 nm – 12 μm).
RPMC Lasers offers a wide selection of
distributed feedback lasers (DFB), including quantum cascade lasers (QCLs). Available in NIR, SWIR, and LWIR wavelengths, these single-mode DFB laser diodes offer a mode-hop-free tunable, single-frequency output and are available in both free-space and fiber-coupled configurations, as well as fully turnkey options for the QCLs. DFB lasers are perfect for gas sensing, DIAL, IR absorption spectroscopy, interferometry, and night vision applications.
Koheras single-frequency fiber lasers are longitudinally single-mode and offer extremely low phase- and intensity noise levels. Available in the erbium or ytterbium wavelength ranges and with frequency conversion to many other bands. Reliability is our highest priority, and the all-fiber DFB design ensures robust and reliable operation for thousands of hours. Koheras lasers are extremely stable and mode-hop-free – even under changing environmental conditions. We can deliver shot-noise-limited lasers for applications demanding extra low-intensity noise.
distributed feedback diode lasers with free-space beam or fiber coupling at numerous wavelengths: 1030 nm, 1047 nm, 1053 nm and 1064 nm are available from stock. In order to match the gain maximum of popular amplifying media as seed lasers, temperature tuning and wavelength selection are offered for the above standard laser wavelengths.
Distributed feedback lasers are single-mode lasers containing an integrated grating structure. The result is a single-mode emission at an outmost precise wavelength with an extremely narrow linewidth. eagleyard provides the largest variety of wavelengths available on the market. Find your suitable
DFB laser product between 633 and 1083 nm with output powers from 10 to 150 mW.
Alpes Lasers offers
single-mode, tunable DFB lasers with wavelengths from 4 to 14 μm and powers up to hundreds of milliwatts. These lasers are able to emit a single wavelength at a time. They can be tuned within a range that can reach up to 10 cm −1; there exists a variety of modulation schemes which can be used for different purposes.
Distributed feedback lasers (DFB lasers) simultaneously provide smooth, tunable control of wavelength and the extremely narrow spectral width required for precise fiber optic communication and spectroscopy applications. Integrated modules provide further narrowing of the spectral line in a compact OEM package that features simple tuning interface.
G&H offers a broad range of
DFB lasers in the C-band and L-band on 50 or 100 GHz channel spacing as well as at 1310 nm, 1064 nm, and custom wavelengths. Power level options include 40–100 mW out of the fiber for high power 14-pin lasers and 10-18 mW options for high bandwidth 7-pin configurations.
single-frequency fiber lasers are based on UV Bragg grating technology applied to active rare-earth photosensitive fibers. The ultra-short cavity and the phase-shifted design permit ultra-narrow linewidth and robust mode-hop-free laser operation, ideal for various sensor applications (1.5 and 2 µm available upon request).
Benefits and features:
wavelength range 1530 – 1565 nm and 2 µm output power: >10 mW (> 10 µW for low noise version) single longitudinal mode narrow linewidth, low phase noise, mode-hop-free linear polarization, PM available low optical feedback sensitivity
DLC DFB pro lasers integrate both distributed-feedback (DFB) and distributed Bragg reflector (DBR) lasers. Available wavelengths include 633 nm and the entire range from 760 nm to 3500 nm. Three laser heads accommodate different diode packages. Due to the absence of alignment-sensitive components, the DLC DFB pro lasers exhibit an exceptional stability and reliability.
Sacher Lasertechnik offers single-mode narrow-linewidth
distributed feedback lasers emitting between 760 nm and 2800 nm. Free space and fiber pigtailed versions available.
SHIPS TODAY: Fiber-coupled DFB laser diodes (
1030 nm DFB, 1064 nm, 1310 nm, 1550 nm or any wavelength between 1250 nm and 1650 nm) are offered as stock items or associated with a CW or pulsed laser diode driver. They are compatible with our high speed nanosecond pulsed drivers or low noise laser diode driver for ultra-narrow linewidth single frequency emission. The single-mode laser diode can reach high powers up to 500 mW in the nanosecond pulse regime. Most turn-key diode & driver solutions are optimized for single-shot to CW performances with pulse durations down to 1 ns. The laser diode precision pulses are generated internally by an on-board pulse generator, or on demand from an external TTL signal.
See also our tutorial on
fiber-coupled laser diodes.
 H. Kogelnik and C. V. Shank, “Stimulated emission in a periodic structure”, Appl. Phys. Lett. 18, 152 (1971); https://doi.org/10.1063/1.1653605
 H. Kogelnik and C. V. Shank, “Coupled-wave theory of distributed feedback lasers”, J. Appl. Phys.43 (5), 2327 (1972); https://doi.org/10.1063/1.1661499
 A. Yariv, “Coupled-mode theory for guided-wave optics”, IEEE J. Quantum Electron. 9 (9), 919 (1973); https://doi.org/10.1109/JQE.1973.1077767
 H. W. Yen et al., “Optically pumped GaAs waveguide lasers with a fundamental 0.11 μ corrugated feedback”, Opt. Commun. 9, 35 (1973); https://doi.org/10.1016/0030-4018(73)90330-1
 K. H. Ylä-Jarkko and A. B. Grudinin, “Performance limitations of high-power DFB fiber lasers”, IEEE Photon. Technol. Lett. 15 (2), 191 (2003); https://doi.org/10.1109/LPT.2002.806827
 B. K. Das et al., “Distributed feedback-distributed Bragg reflector (DFB-DBR) coupled cavity laser with Ti:(Fe:)Er:LiNbO 3 waveguide”, Opt. Lett. 29 (2), 165 (2004); https://doi.org/10.1364/OL.29.000165
 K. Sato, “Chirp characteristics of 40-Gb/s directly modulated distributed-feedback laser diodes”, IEEE J. Lightwave Technol. 23 (11), 3790 (2005); https://doi.org/10.1109/JLT.2005.857753
 A. Schülzgen et al., “Distributed feedback fiber laser pumped by multimode laser diodes”, Opt. Lett. 33 (6), 614 (2008); https://doi.org/10.1364/OL.33.000614
 M. Pollnau and J. D. B. Bradley, “Optically pumped rare-earth-doped Al 2O 3 distributed-feedback lasers on silicon”, Opt. Express 26 (18), 24164 (2018); https://doi.org/10.1364/OE.26.024164
(Suggest additional literature!)
single-frequency operation, single-frequency lasers, distributed Bragg reflector lasers, fiber Bragg gratings, fiber lasers, semiconductor lasers
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