Spectral ripple refers to the modulation that can be seen on top of the spectral density curve. The primary causes of the spectral ripple are the residual reflections from the SLED chip facets and from the fiber facet facing the SLED chip. Typically, spectral ripple is measured by using a high-resolution Optical Spectrum Analyzer (OSA) with 0.1nm resolution. Spectral ripple is more pronounced in high-power SLED devices and is highest around the peak wavelength.

Thanks to their advanced design, EXALOS's SLEDs exhibit an extremely low level of ripple.  Even at high power levels, the spectral ripple is typically 0.1dB.

Low values of spectral ripple are important in order to obtain a clean coherence function, with minimum secondary coherence peaks.