Side Illuminated Optical Fibers: 6.5 Hours Mini Course

This is a 6.5 hours long presentation covering the history of side illuminated optical fibers, demonstrations and hands-on experiments.



Side illuminated optical fiber sensors are a new type of device that can make multiple measurements along an optical fiber with a single detection system: these measurements can be either consecutive or simultaneous.  It represents a complete departure from the regular way, such as in axial illumination, that fibers are used: whereas in axial illumination the fiber’s end face is illuminated, in side illumination, the fiber’s cylindrical surface is illuminated instead.  With this new technique, a surprising amount of light is coupled into the fiber while providing several unexpected advantages and benefits such as:

  1. Low cost: multiple sensing points can be illuminated using inexpensive LEDs, a simple switching technique and a single detection system.
  2. High density of sensing points: the dimension of the light source dictates the number of sensing points per fiber length.  For instance, using 5 mm diameter LEDs, it is possible to accommodate 40 light sources along the length of a 20 cm long optical fiber. This number of sensing points can be increased even further by using 1 micron diameter LEDs.
  3. High spatial resolution: recently, we demonstrated a prototype liquid level optical fiber sensor with a spatial resolution of 3 microns: this resolution can be increased with smaller LED sources.
  4. Multi fold redundancy: the high density of sensing points of this device can also be used to increase its redundancy making it suitable for hostile environments.
  5. High sensitivity and high dynamic range: by adjusting the intensity of each light source, or combining multiple sources to act as a single one, it is possible to obtain an extremely high signal resulting in high sensitivity and high resolution.
  6. High signal to noise ratio: since most of the excitation light is radiated away, the signal to noise ratio of this type of sensor is much higher if compared with regular axial illumination.

In this course, we will explain the basic principles of side illumination, demonstrate the above advantages and benefits and perform simple experiments.


This course will enable you to:

  • Name the pioneers in this field.
  • List the important papers published with this type of configuration.
  • Classify the types of side illuminated optical fiber sensors.
  • Explain how side illuminated light is injected into the fiber.
  • Design different side illuminated optical fibers for distinct applications.
  • Operate a simple colorimeter with multiple samples.
  • Compare the performance between axial and side illuminated optical fibers having a fluorescent cladding.
  • Infer the chemical concentration in a water sample.



Professionals in the water, sensing, spectroscopy and analytical industries.  Researchers, graduate and undergraduate students interested in learning new spectroscopic and sensing techniques.



Introductory level with knowledge of basic algebra and trigonometry.