Superluminescent Diodes – Broadband Light

Deeper Dive into Superluminescent Lasers

Superluminescent Laser Diode Origins

Superluminescent diodes first came into being in 1986 when Dr. Gerard A. Alphonse (RCA Laboratories – now SRI International) enabled high-power superluminescent laser diodes with his novel design. The newly created broadband light source was critical in next-gen fiber optic gyroscopes, low coherence tomography for medical imaging, and fiber-optic communication.

How Does a Superluminescent Laser Diode Work?

As mentioned above, SLEDs are similar to laser diodes, having a p-n junction and an optical waveguide, but lack optical feedback, preventing lasing. These devices become optically active with forward biasing, generating broadband amplified spontaneous emission.

The choice of active material used and the injection current level determines a superluminescent diode’s peak wavelength and intensity. The design of SLDs enables high, single-pass amplification for generating spontaneous emission along the waveguide. However, due to insufficient feedback, no lasing action occurs. The lack of optical feedback is due to anti-reflection coatings (ARC) on the facets and angling the waveguide off-axis (see the diagram below).

a) Facet feedback and wavelength resonances in the optical emission spectrum of a multimode Fabry-Perot laser;

b) power spectral density of a superluminescent light emitting diode

Applying a forward voltage to the SLEDs active region generates an injection current. This current flows from the positive (p-doped – extra electron holes) section to the negative (n-doped – extra electrons) section, crossing the active region (i.e., the p-n junction). The current flow across this junction, limited to one direction due to its inherent design, generates light through spontaneous and random recombination of positive electron holes and negative electrons, amplified when propagating along the waveguide.

The design of a superluminescent diode’s p-n junction allows for multiple energy bands, which provide a broad range of optical frequencies (wavelengths), alternatively referred to as broadband light.

Key Features of the BeST-SLED: Integrated Spectral Bench

• 2 – 6 Superluminescent Diodes (SLEDs) in a single package
• All SLEDs can be run from 0-100% of maximum rating
• Fiber-Coupled Output Powers ranging from 12mW – 40mW
• The best combination of power and spectrum width in multi-SLED modules
• Each SLED comes with a built-in independent monitor photodiode
• Optional: Integrated InGaAs Power Meter
• Internally Optimized for maximum coupling efficiency with PM 1300 or 1550-XP Fiber
• Integrated Optical Isolation (35dB)
• Light Output: FC/APC Connector (Optional FC/PC or SMA)

Key Features of the BeST-SLED: Optical Spectral Engine

• 2 – 6 Superluminescent Diodes (SLEDs) in a single package
• Fiber Coupled Output Powers ranging from 12mW – 40mW
• The best combination of power and spectrum width in multi-SLED modules
• Each SLED comes with a built-in independent monitor photodiode
• Internally Optimized for maximum coupling efficiency with PM1300 or 1550-XP Fiber
• Light Output: FC/APC Connector (Optional FC/PC or SMA)

Superluminescent Laser Applications

Our SLED products are perfect for many applications, including Telecom Test Equipment, Optical Component Testing, Medical Optical Coherence Tomography, Fiber Bragg Grating (FBG) Sensors, Optical Sensing, Coherent Communication, Polarization Testing, White Light Interferometry, Industrial Optical Coherence Tomography, Spectroscopy, Biomedical Imaging Systems, Metrology, Fiber Optic Gyroscopes, and Holography.

For example, Optical Coherence Tomography (OCT) is a high-resolution and deeply penetrating 3D imaging method. Luxmux’s broadband light sources are suitable for both spectral domain and swept source OCT. Customers will see an increased axial resolution with our broadband, tunable light sources. Luxmux SLEDs provide superior performance for Time-Domain (TD) OCT systems, which require SLEDs with a strong spectral shape and optical coherence for sidelobe suppression.

Medical applications include ophthalmology, cardiology, oncology, and biomedical imaging, and measurement capabilities can be used to verify the dimensions of molds and other parts.

SLDs can replace traditional incandescent lamps for applications requiring a low level of optical power. While incandescent lamps can be cost-effective and adequate for particular application requirements, the relatively low brightness level can be a detriment, as this can cause large increases in the time required for measurement or can result in a low signal-to-noise signal ratio.

Providing New Dexterity: Creating Ultra Broadband Solutions

Luxmux has developed broadband source solutions in a groundbreaking way, offering an unparalleled usable range of the electromagnetic spectrum with more user control than any similar product can offer today.

Luxmux developed its products to integrate the near-infrared (NIR) region (1.2um – 1.7um) of the electromagnetic spectrum in a way that suits any user’s needs. Luxmux does not restrict broadband source products to a specific set of values on the spectral bandwidth. Although individual lights may have limitations on their nm range, Luxmux overcomes these limitations through the successful combination of optical filters that selectively transmit lights of different wavelengths. We call this method “spectral stitching,” and it can be applied across the entire NIR range, as well as extended into the VIS range.

Spectral stitching helps to increase the reach and coordination of different spectral bands. This method enables them to blend more smoothly, effectively, and efficiently, much like the simultaneous strengthening of muscles in our fingers, hands, and wrists, while also increasing coordination. 

Luxmux has reached a new level of dexterity and experience in the field of optical spectral combination. We have developed an elegantly designed and assembled scheme that allows users to tailor this technology to their individual needs through this competency. 

Read the full article here.

Low Degree of Polarization Broadband Source for Test & Measurement

Multiple Platform Low DoP Light Source

The new Luxmux Integrated Spectral Bench (ISB) Low Degree of Polarization (DoP) builds upon the proven strengths of the ISB system while adding innovation where it matters most for our customers. Forward-looking compatible support for the installed communication protocols, combined with several new features, gives our customers the capabilities they need to achieve their goals. The Luxmux Low DoP platform will outshine the others with its size, selection modularity, reliability, and flexibility. We can’t wait to see what you accomplish with the new Luxmux ISB source.

Customer-Focused Innovation:

The LUXMUX Optical Spectral Engine SLED (left) and  Multi-SLED Integrated Spectral Bench (right)

The Luxmux Low DoP Integrated Spectral Bench is a depolarized broadband optical source. The G1 (Single SLED) and G2 (Multi-SLED) series come in a range of power levels and spectral coverages. The ISB is designed as a compact and integrated light source unit. The ISB sources are extraordinarily robust and reliable, built for intensive use, and can replace multiple single SLED sources. DoP is an important property of light sources, as it directly relates to the accuracy of optical component characterization, the sensitivity of sensor systems, and the quality of optical signals in optical communication systems.

Our light sources are presented in an optical platform, optimized for cost-effective development and manufacturing of optical spectral combining. Our systems are designed to help manage an industry’s test and measurement needs that require flexibility and dynamic performance. We aim to offer researchers, designers, and manufacturing engineers a broadband solution with the broadest singular spectrum range of > 400 nm for Low DoP characteristics of SLED photonic light sources.

Luxmux’s low DoP solutions are relevant to applications that require a stable and accurate DoP as a reference light source for system monitoring and quality assurance. Low DoP light source measurements require different capabilities and limitations. Luxmux offers multiple spectrum configurations and operational capabilities to suit the requirements of various applications. Luxmux provides a wide variety of Superluminescent Light Emitting Diodes (SLED) for the Near Infrared Range (NIR) at different wavelengths ranging from 1265nm to 1725nm, with different output power and bandwidth values. It exhibits excellent wavelength stability, high power, low-intensity noise, low coherence, and significantly large bandwidth.

Key Capabilities:

The ISB (Integrated Spectral Bench) exhibits excellent wavelength stability, high power, low-intensity noise, low coherence, and significantly large bandwidth. The Luxmux Low DoP series of all-semiconductor optical sources has a wide selection of wavelengths that can be offered singularly or combined, covering the entire range of telecom spectral bands (O to U). The CW output standard model provides excellent stability in output power and spectrum and a driver circuit to provide overlapping spectral coverage from up to six individual light sources. This user-controlled chassis offers complete control of all light sources enclosed. The ISB systems come with USB, RS-232, and Ethernet communication ports for an easy, flexible interface with computers and other instruments. It is an ideal source for OCT, fiber sensors, fiber gyros, PM patch cord extinction ratio (ER) measurement, and general-purpose test and measurement.

Highlights:

• Between one and six superluminescent diodes (SLEDs) in a single package
• All SLEDs can be run from 0 – 100% of the maximum rating
• Fiber-Coupled Output Power > 12mW
• Bandwidth FWHM > 150nm, @10dB > 180nm
• The best combination of power and spectrum width in multi-SLED modules
• Each SLED comes with a built-in independent monitor photodiode
• Optional: Integrated InGaAs Power Meter
• Internally Optimized for maximum coupling efficiency with PM1550-XP Fiber
• Light Output: FC/APC Connector (Optional FC/PC or SMA)
• Customized ASE design and spectrum combination
• Fiber pigtail or FC receptacle output
• Improved reliability by integrated dual optical isolator
• Individual SLED control, user-defined spectrum flexibility
• Standard operating temperature: 0°C to 65°C.
• Extended range -20°C to 70°C
• Telcordia certification, RoHS Compliance
• Intensity modulation is available upon request

Functional Description

G1 and G2 Series Options:

• Low-Degree of Polarization (DoP): the ISB provides under 10 percent DoP across the entire 1265nm – 1725nm range. This minimizes polarization sensitivity of fiber sensors and reduces the effects of polarization-dependent loss
• Free Space: This selection results in a direct laser beam for higher-power applications that do not require fiber optics.
• Power Meter: an integrated InGaAs Power Meter can be added to ISB models upon customer request. The power meter adapters can come with FC/APC, FC/PC, or SMA connector.

How Can We Help?

With over 25 years experience providing semiconductor lasers to researchers and OEM integrators working in various markets and applications, and 10s of thousands of units fielded, we have the experience to ensure you get the right product for the application. Working with RPMC ensures you are getting trusted advice from our knowledgeable and technical staff on a wide range of laser products.  RPMC and our manufacturers are willing and able to provide custom solutions for your unique application.

If you have any questions, or if you would like some assistance please Contact Us here. Furthermore, you can email us at info@rpmclasers.com to talk to a knowledgeable Product Manager.

Alternatively, use the filters on this page to assist in narrowing down the selection of superluminescent lasers for sale. Finally, head to our Knowledge Center with our Lasers 101 page and Blogs, Whitepapers, and FAQ pages for further, in-depth reading.

Finally, check out our Limited Supply – In Stock – Buy Now page: This page contains an ever-changing assortment of various types of new lasers at marked-down/discount prices.