RP Photonics logo
RP Photonics
Consulting Software Encyclopedia Buyer's Guide

Short address: rpp-con.com

Dr. Paschotta, the founder of RP Photonics, supports your R & D with his deep expertise. Save time and money with efficient support!

Short address: rpp-soft.com

Powerful simulation software for fiber lasers and amplifiers, resonator design, pulse propagation and multilayer coating design.

Short address: rpp-enc.com

The famous Encyclopedia of Laser Physics and Technology provides a wealth of high-quality scientific and technical information.

Short address: rpp-bg.com

In the RP Photonics Buyer's Guide, you easily find suppliers for photo­nics products. As a supp­lier, you can profit from enhanced entries!

Learn on lasers and photonics every day!
VL logo part of the

Superluminescent Diodes

<<<  |  >>>  |  Feedback

Buyer's Guide

The ideal place to find suppliers for photonics products: high-quality information, simple and fast, respects your privacy!

22 suppliers for superluminescent diodes are listed.

Your are not yet listed? Get your entry!

Ask RP Photonics what kind of superluminescent source is most suitable for your application.

Acronym: SLD or SLED

Definition: broadband semiconductor light sources based on superluminescence

German: superlumineszente Dioden

Category: photonic devices

How to cite the article; suggest additional literature

Superluminescent diodes (also sometimes called superluminescence diodes or superluminescent light-emitting diodes = superluminescent LEDs) are optoelectronic semiconductor devices which emit broadband optical radiation based on superluminescence. In terms of construction, they are similar to laser diodes, containing an electrically driven p–n junction and an optical waveguide. Importantly, however, SLDs lack optical feedback by reflections, so that no laser action can occur. Parasitic optical feedback from the facets, which could lead to the formation of resonator modes and thus to pronounced structures in the optical spectrum and/or to spectral narrowing, is suppressed by means of tilting the facets relative to the waveguide, and can be suppressed further with anti-reflection coatings. Essentially, an SLD is a semiconductor optical amplifier with no input signal, where weak spontaneous emission into the waveguide mode is followed by strong laser amplification (→ amplified spontaneous emission).

A frequently used acronym for the superluminescent diode is SLD. The alternative acronym SLED is also used for surface-emitting LED, i.e., with a totally different meaning, so that confusion can arise.

Wavelength, Power, and Optical Bandwidth

Most superluminescent diodes emit in one of the wavelength regions around 800 nm, 1300 nm, and 1550 nm. However, devices for other wavelengths are available, also in the visible domain.

Typical output powers are in the range from a few milliwatts to some tens of milliwatts, and spatially the emission is close to diffraction-limited, i.e., the spatial coherence and beam quality are very high. Therefore, the broadband output can be easily launched into a single-mode fiber. Fiber-coupled SLDs are in fact most common.

The optical bandwidth of an SLD is usually some tens of nanometers, sometimes even above 100 nm. This corresponds to a coherence length of a few tens of microns, sometimes even only a few microns. Due to gain narrowing, there is a trade-off between high output power and broad bandwidth, which can however be improved with various methods. This trade-off, and not the lack of optical feedback, is the main reason why SLDs deliver lower optical powers than laser diodes.

Another factor, which is important for some applications, is wavelength stability, particularly under conditions of variable temperatures and aging. Typically, the center wavelength drifts by some fraction of a nanometer per Kelvin temperature change, following the drift of the semiconductor's gain spectrum.

Various Technical Issues

SLDs should be carefully protected against external optical feedback. Even small levels of feedback can reduce the overall emission bandwidth and the output power, or sometimes even lead to parasitic lasing, causing narrow spikes in the emission spectrum. Some devices may even be damaged by optical feedback. Note that the Fresnel reflection from a perpendicularly cleaved fiber end is already well above the level of feedback which can be tolerated.

To a similar extent as laser diodes, SLDs are sensitive to electrostatic discharges and current spikes e.g. from ill-designed driver electronics. However, when treated carefully and operated well within the specifications, SLDs can easily last for tens of thousands of hours of operation.


SLDs are applied in situations where a smooth and broadband optical spectrum (i.e. low temporal coherence), combined with high spatial coherence and relatively high intensity, is required. Some examples are:

Possible Alternatives

For higher output powers, an SLD may be replaced with an unseeded fiber amplifier. However, fiber-based sources are substantially more expensive.

In cases where very low optical powers are sufficient, a simple bulb may be used. However, the brightness of a bulb is orders of magnitude smaller than that of an SLD, so the difference in, e.g., signal-to-noise ratio or speed of some measurement can be huge.

In principle, an SLD is a semiconductor optical amplifier (SOA) with no input signal, but it is optimized for a good combination of output power and bandwidth, and therefore better suited for broadband light generation than an all-purpose SOA.


[1]M. C. Amann and J. Boeck, “High efficiency superluminescent diodes for optical-fibre transmission”, Electron. Lett. 15, 41 (1979)
[2]G. A. Alphonse et al., “High-power superluminescent diodes”, IEEE J. Quantum Electron. 24 (12), 2454 (1988)
[3]C. Holtmann et al., “High power superluminescent diodes for 1.3 μm wavelengths”, Electron. Lett. 32 (18), 1705 (1996)
[4]V. R. Shidlovski and J. Wei, “Superluminescent diodes for optical coherence tomography”, Proc. SPIE 4648, 139 (2002)
[5]E. V. Andreeva et al., “Superluminescent InAs/AlGaAs/GaAs quantum dot heterostructure diodes emitting in the 1100–1230-nm spectral range”, Quantum Electron. 36 (6), 527 (2006)
[6]C.-F. Lin and B.-L. Lee, “Extremely broadband AlGaAs/GaAs superluminescent diodes”, Appl. Phys. Lett. 71 (12), 1598 (1997)
[7]Z. Q. Li and Z. M. Simon Li, “Comprehensive modeling of superluminescent light-emitting diodes”, IEEE J. Quantum Electron. 46 (4), 454 (2010)
[8]A. Kafar et al., “High-optical-power InGaN superluminescent diodes with 'j-shape' waveguide”, Appl. Phys. Expr. 6, 092102 (2013)

(Suggest additional literature!)

See also: superluminescent sources, superluminescence, white light sources, white light interferometers

How do you rate this article?

Your general impression: don't know poor satisfactory good excellent
Technical quality: don't know poor satisfactory good excellent
Usefulness: don't know poor satisfactory good excellent
Readability: don't know poor satisfactory good excellent

Found any errors? Suggestions for improvements? Do you know a better web page on this topic?

Spam protection: (enter the value of 5 + 8 in this field!)

If you want a response, you may leave your e-mail address in the comments field, or directly send an e-mail.

If you like our website, you may also want to get our newsletters!

If you like this article, share it with your friends and colleagues, e.g. via social media:

cover of print encyclopedia

The Encyclopedia of Laser Physics and Technology is also available in the form of a two-volume book. Maybe you would enjoy reading it also in that form! The print version has a carefully designed layout and can be considered a must-have for any institute library, laser research group, or laser company. You may order the print version via Wiley-VCH.


RP Fiber Power – the versatile Fiber Optics Software

An Amazing Tool

RP Fiber Power software

This amazing tool is extremely helpful for the development of passive and active fiber devices.


Watch our quick video tour!

Single-mode and Multi­mode Fibers


Calculate mode properties such as

  • amplitude distributions (near field and far field)
  • effective mode area
  • effective index
  • group delay and chromatic dispersion

Also calculate fiber coupling efficiencies; simulate effects of bending, nonlinear self-focusing or gain guiding on beam propagation, higher-order soliton propagation, etc.

Arbitrary Index Profiles

A fiber's index profile may be more complicated than just a circle:

special fibers

Here, we "printed" some letters, translated this into an index profile and initial optical field, propagated the light over some distance and plotted the output field – all automated with a little script code.

Fiber Couplers, Double-clad Fibers, Multicore Fibers, …

fiber devices

Simulate pump absorption in double-clad fibers, study beam propagation in fiber couplers, light propagation in tapered fibers, analyze the impact of bending, cross-saturation effects in amplifiers, leaky modes, etc.

Fiber Amplifiers

fiber amplifier

For example, calculate

  • gain and saturation characteristics (for continuous or pulsed operation)
  • energy transfers in erbium-ytterbium-doped amplifier fibers
  • influence of quenching effects, amplified spontaneous emission etc.

in single amplifier stages or in multi-stage amplifier systems, with double-clad fibers, etc.

Fiber-optic Telecom Systems

eye diagram

For example,

  • analyze dispersive and nonlinear signal distortions
  • investigate the impact of amplifier noise
  • optimize nonlinear management and the placement of amplifiers

Find out in detail what is going on in such a system!

Fiber Lasers

fiber laser

For example, analyze and optimize the

  • power conversion efficiency
  • wavelength tuning range
  • Q switching dynamics
  • femtosecond pulse generation with mode locking

for lasers based on double-clad fiber, with linear or ring resonator, etc.

Ultrafast Fiber Lasers and Amplifiers

fiber laser

For example, study

  • pulse formation mechanisms
  • impact of nonlinearities and chromatic dispersion
  • parabolic pulse amplification
  • feedback sensitivity
  • supercontinuum generation

Apply any sequence of elements to your pulses!

… and even Bulk Devices

regenerative amplifier

For example, study

  • Q switching dynamics
  • mode-locking behavior
  • impact of nonlinearities and chromatic dispersion
  • influence of a saturable absorber
  • chirped-pulse amplification
  • regenerative amplification

RP Fiber Power is an extremely versatile tool!

Mode Solver

fiber modes

For example, calculate

  • amplitude and intensity profiles
  • effective mode areas
  • cut-off wavelengths
  • propagation constants
  • group velocities
  • chromatic dispersion

All this is calculated with high efficiency!

Beam Propagation

beam propagation

Propagate optical field with arbitrary wavefronts through fibers. These may be asymmetric, bent, tapered, exhibit random disturbances, etc.

See our demo video for numerical beam propagation.

Laser-active Ions

level scheme

Work with the standard gain model, or define your own level scheme!

Can include different ions, energy transfers, upconversion and quenching effects, complicated pumping schemes, etc.

Multiple Pump and Signal Waves, ASE

optical channels

Define multiple pump and signal waves and many ASE channels – each one with its own transverse intensity profile, loss coefficient etc.

The power calculations are highly efficient and reliable.

Simple Use and High Flexibility Combined

For simpler tasks, use convenient forms:

signal parameters

Script code is automatically generated and can then be modified by the user. A powerful script language gives you an unparalleled flexibility!

High-quality Documentation and Competent Support

The carefully prepared comprehensive documentation includes a PDF manual and an interactive online help system.

Competent technical support is provided: the developer himself will help you and make sure that any problem is solved!

Our support is like included technical consulting.

Boost your competence, efficiency and creativity!

  • Stop fishing in the dark! Develop a clear quantitative understanding of your devices.
  • Explore the effects of possible design changes on your desk.
  • That way, get most efficient in the lab.
  • Find optimized solutions efficiently, minimizing time to market.
  • Get new ideas by playing with your models.

Efficiency and success of
R & D are not a matter of chance.

See our detailed description with many case studies!

Contact us to get a quotation!

– Show all banners –

– Get your own banner! –