Luxmux Superluminescent Diodes: Integrated Spectral Bench And Optical Spectral Engine

Luxmux’s BeST-SLED® light sources use between one and six superluminescent diodes (SLEDs), which is where the BeST-SLED name is derived from. There are three different types of BeST-SLEDs: Single-SLED G1, Multi-SLED G2 and Multi-SLED G3. The key difference between the Single-SLED and the Multi-SLEDs is simple: with the Single-SLED there is only one SLED, whereas the Multi-SLEDs have between two and six SLEDs.

The differences between the two Multi-SLEDs – G2 and G3 – is more precise. With the G2, each SLED comes with a built-in independent monitor photodiode, and there is one thermoelectric cooler (TEC) that controls the temperature for all of the SLEDs. With the G3, however, each SLED comes with a TEC, and there is one monitor photodiode for the combined output of all SLEDs.

But there is another subdivision to the G2 and G3: they are either an Integrated Spectral Bench (ISB) or an Optical Spectral Engine (OSE). The G1 is available only as an ISB.

The OSE is a 32-pin butterfly package that is versatile and compact; powerful yet efficient. Luxmux does not use spectral emission masks to give off the appearance of a spectrally-balanced and Gaussian appearance. Rather, we use the SLED light sources in isolation, without any additional spectrum-shaping techniques. This maintains the purity of the SLED, and introduces zero side effects or unwanted artifacts. Adaptive power selection and other control adjustments make this source ideal for solutions in both the lab and manufacturing settings.

The ISB takes the OSE one step further. The ISB platform is a self-managed command- and control-centre for the OSE. It allows selective management of SLED drivers, TEC controllers, power meter, polarization control and modulation of the light source. The system can manage up to six different SLEDs with superior bandwidth combination abilities, coverage of the key telecom/datacom wavelength bands (1300, 1340, 1390, 1430, 1480, 1550, 1615, 1680nm) and more. The ISB devices share a common interface that can hold FP laser and SLED sources. They can perform at both constant power and current operating models, providing up to a 10db-sized power tuning range.

Think of it like this: the OSE and ISB light sources can be considered the “new CPU” of the optical light sources. When comparing these product lines to our communication and computing counterparts, the analogy can be seen as this: the main difference between CPU and GPU architecture is that a CPU is designed to handle a wide-range of tasks quickly (as measured by CPU clock speed), but are limited in the concurrency of tasks that can be running. A GPU is designed to provide high-resolution images and video concurrently. We like to think of our light source as the GPU of the NIR spectral domain, whereby we utilize bandwidth as the means to get extra mileage and distance out of singular traditional light sources, but we combine them in a meaningful and useful way. This is one of the main reasons why GPUs are faster for computing than CPUs. We target our light source models to provide the means to deliver an optically-stable spectrum used for interrogation, analysis, and the ability to consolidate light spectrum across the NIR spectral region.

There are many variants of both the OSE and ISB that enable a broad array of applications and can feasibly encompass several different emitter types. The emitter types have a specific set of spectral properties that make them ideal for different applications. These include:

Dependence of power on current: We manage, optimize and maximize the total optical power emitted by a group of SLEDs, which, in turn, positively optimizes the drive current. Unlike single-frequency lasers, our combined SLED diodes have an output intensity that does not exhibit a sharp threshold, but gradually increases with current. The Luxmux BeST-SLED unit is a demonstrably capable product that includes a reliable fiber-coupled light source with broad bandwidth and ample power, and is also compact and affordable. The use cases with this highly flexible unit allow “on-the-fly” combination of SLEDs with an interactive guided user interface (GUI), which allows the user to manage a broad spectrum and multiple central wavelengths. Users also have the option to initiate their own plug-and-play mode by setting up single individual spectrums, combined groups of spectrums, or a broadband spectrum with high resolution. The BeST-SLED® can provide all these features, which, as a result, provide a multitude of superior characteristics and a greater ability to incorporate multiple applications.

Centre wavelength and optical bandwidth: the optical power is emitted and distributed over a wide spectral range by multiple SLEDs. These two parameters – optical bandwidth (BW) and peak wavelength – are related to the power density distribution at different wavelengths.

Spectral ripple: this refers to the measure of the variation of the spectral-power-density, which can be observed through a small change of the wavelength and detected using high-resolution OSA. Best-SLED products can be selectively binned for respective ripple performance across multiple SLEDs.

Polarization: the optical field emitted by the SLED chips has a certain degree of polarization (DOP). This is due to the optical field being a combination of unpolarized spontaneous emission and amplified radiation. Accurate and fast characterization of DOP is increasingly important, particularly in telecommunications and fibre optic sensing applications. The Luxmux ISB can be configured (DOP </= 10%) across the spectrum of interest, thus providing a system that can be used for accurate optical component characterization, as well as testing of the sensitivity of the sensor systems and the quality of optical signals in the optical communication systems.

Relative intensity noise (RIN): the RIN represents the ratio between the noise power and the average power after detection. The measurement unit used is dB/Hz. Typical values measured for SLEDs in a frequency range extend from DC up to 50 MHz.

Read More: Key Features of the ISB:

– Configurable spectral bandwidth (up to six different SLEDs available)

– Optical power: up to 40mW

– Temperature controlled ±0.1ºC

– Configurable output connector FC/PC or FC/APC

– Dimensions: 178.50 mm x 114.00 mm x 39.93 mm

– Active cooling

– Interactive dashboard: a highly intuitive graphical user interface which often provides at-a-glance views of key performance indicators. This can be used as a powerful information management tool that visually tracks and analyses the performance of the broadband spectrum.

– USB, RS232, Ethernet connection option to allow the remote control of the light source through computer interface.

– Individual control 0-100% of the power of each SLED, with selectable on/off options (Manually/Automatic)