In recent years, photonic sensors have generated an increasing
interest because of their already well-known advantages, as immunity
to electromagnetic interferences, high sensitivity, no impact noise
and working in harsh environment. Photonic sensors are generally
classified according to the physical principle including endogenous
sensors and exogenous sensors. Exogenous sensors often use the
physical principle that light is altered in intensity of spread; reflex;
scattering; refraction; or wavelength conversion due to interaction
with the external environment. These sensors are relative easiness of
fabrication, but the processing of light signals varies due to the
complexity of the external environment requiring high sensitivity.
The endogenous photonic sensor uses the physical principle that the
optical properties of sensor structure is changed when interacting
with the environment. Therefore, they have very high sensitivity,
easiness of signal processing and compact device size. However, the
disadvantage of endogenous photonic sensor is the ability to reuses
and selectivity. Endogenous photonic sensors are being promoted in
research because of their extremely high sensitivity which can be
combined with many specializations in chemistry and biology. At
present, the sensitivity and selectivity of endogenous photonic
sensors can be enhanced and have had some very good results.
