Optical Sources
Photonic devices - Bas parameters

Optical sources and radiation are characterized by a set of radiometric quantities, including:

• flux: expresses the rate of light energy (power) emitted by radiation, or the number of photons emitted per second (unit: W·s^{^(−1)});

• intensity: the flux emitted per unit solid angle along a given direction (angular distribution of the radiation) (unit: W·sr⁻¹ or s⁻¹·sr⁻¹);

• luminance: intensity of radiation per unit area normal to the direction of propagation (unit: W·m⁻² or sr⁻¹ or s⁻¹·m⁻²sr⁻¹);

• irradiance: the flux density received per unit area illuminated by radiation (unit: W·m⁻² or s⁻¹·m⁻²).

Each quantity is defined by its spectral density (“spectral quantity,” generally expressed...