Optical fiber-based liquid level sensor

A liquid level sensor based on etched D-shaped silica optical fibers is presented. The optical transmission of the sensor depends on the liquid level. The sensor can be realized as a continuous level sensor with a high resolution and requires only one fiber and one optical source and detector. We have demonstrated a sensor with a resolution of ~1 mm. The sensor works for liquids with refractive indices greater than ~1.45. We show that the sensor response is the same for increasing and decreasing liquid levels.