Near-Infrared SLEDs & SOAs
What are Superluminescent Diodes (SLEDs)?
A Superluminescent Light-Emitting Diode (SLED) or short Superluminescent Diode (SLD) is a high-performance, edge-emitting semiconductor-based light source that delivers a broadband optical spectrum (similar to a Light-Emitting Diode, LED) in combination with high output power levels and a spatially coherent, transverse single-mode output beam (similar to a laser diode, LD).
SLEDs can be realized on a wide range of semiconductor material systems, including GaN compound devices, having typical emission wavelengths from 390nm to 530nm, or GaAs-based devices, offering emission wavelengths from 630nm to 1100nm, or InP-based devices, covering the wavelength range from 1200nm to 1700nm, typically.
The broadband optical output of SLED devices can have a Gaussian-shaped spectrum or a more rectangular shape, sometimes with a characteristic double-peak feature. The optical spectrum of SLEDs has a typical 3dB bandwidth of 3-10 nm in the visible-wavelength range but can reach values up to 200 nm emitted from a single chip for SLEDs in the near-infrared wavelength range. Typical output power values for single-mode SLED devices range for a few mW to a few hundred mW in free space. Even though not common, high-power and multi-mode SLEDs have also been realized.
In terms of manufacturing aspects, the fabrication processes of SLED devices are comparable to standard LD chip manufacturing and show a similar economy of scale. Realizing a broadband semiconductor optical amplifier (SOA) device is also related to an SLED as the latter can be considered a broadband light source with a built-in amplifier that is generating amplified spontaneous emission (ASE) light at the output facet.
Why are SLEDs Compelling Light Sources?
Because of the lateral single-mode optical waveguide, the light output of an SLED is spatially highly coherent, which results in efficient coupling from the chip to single-mode optical fibers or photonic waveguides, similar to LD devices. Likewise, efficient beam collimation with standard collimation optics can be accomplished with high power and high intensity levels, resulting in broadband light with high power spectral density (PSD) values that are exceeding the performance of LED-based light sources by several orders of magnitude.
SLED devices offer high spatial coherence in combination with low temporal coherence, the latter being a consequence of the broad spectral emission of these devices. Typical coherence lengths that can be achieved with a single SLED device are in the range of 5-30 microns, the exact value depending on the optical bandwidth, the center wavelength and the exact spectral shape.
Furthermore, the light output of SLEDs is, similar to LDs, highly polarized with typical polarization extinction ratio (PER) values of 7-20 dB (5:1 to 100:1), which can be beneficial compared to the unpolarized light output of LED devices.
The combination of short coherence length and high output power makes SLEDs compelling light sources for a wide range of applications, including interferometric techniques in the field of biomedical imaging, fiber optic gyroscopes, fiber sensing, metrology, etc. but also including other applications such as machine vision or novel display architectures for AR/VR systems or head-up displays (HUDs) where speckle noise or other unwanted coherence artifacts can be efficiently eliminated.
Best-in-Class EXALOS SLEDs based on Advanced Semiconductor Technology and Design Concepts
The EXALOS SLED devices offer best-in-class optical performance, covering an ultra-broad wavelength range from 400 nm to 1700 nm and offering large optical bandwidth values in combination with high fiber-coupled output power values of up to 50 mW or even more. The EXALOS portfolio in SLEDs has the broadest product offering on the market due to its advanced semiconductor design and manufacturing capabilities on three different material systems, including GaN, GaAs and InP.
The EXALOS SLED devices also offer superior quality and long-term reliability with mean-time-to-failure (MTTF) values of several 10k, several 100k or even million hours of operation, depending on the exact performance parameters of the SLED.
The EXALOS SLED devices have been qualified for a wide range of industry segments, from biomedical imaging such as biometry or Optical Coherence Tomography (OCT) to Fiber Optic Gryoscopes (FOGs) for aerospace, automotive, space or defense applications.
Related Products
| Product | Description | |
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Ultra-compact RGB modules utilizing EXALOS low-threshold Visible laser diodes and/or Superluminescent LEDs. |
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Low-threshold laser diodes (400-680 nm) for AR displays and next-gen optical systems that require low power consumption. |
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Near-Infrared and Visible SLEDs with wavelengths from 400 to 1700 nm, available in various power, bandwidth, and packaging options. |
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