A method for manufacturing of a photonic circuit including a silicon nitride light waveguide; said method comprising: depositing silicon nitride on a substrate for forming a structure comprising a silicon nitride light waveguide on a substrate; processing the structure for forming the photonic circuit; wherein the processing of the structure comprises the structure being exposed to electromagnetic radiation having an energy sufficiently large to excite electrons to a conduction band in the silicon nitride light waveguide; the method further comprising exposing the silicon nitride light waveguide to a charge carrier exciting condition for exciting electrons from charge traps in the silicon nitride light waveguide to a conduction band and electron holes from charge traps in the silicon nitride light waveguide to a valence band for depopulating charge traps so as to reduce propagation loss of light through the silicon nitride light waveguide wherein the exposing of the silicon nitride light waveguide to the charge carrier exciting condition comprises illuminating the structure with light having an energy larger than an energy difference between a charge trap energy level and a conduction band energy level or a valence band energy level, the light having an energy smaller than a material bandgap in the silicon nitride light waveguide; or wherein the exposing of the silicon nitride light waveguide to the charge carrier exciting condition comprises transmitting light through the light waveguide, wherein the light has an energy larger than an energy difference between a charge trap energy level and a conduction band energy level or a valence band energy level, the light having an energy smaller than a material bandgap in the silicon nitride light waveguide; or wherein the exposing of the silicon nitride light waveguide to the charge carrier exciting condition comprises exposing the structure to a temperature in a range of 150-400°C. depositing silicon nitride on a substrate for forming a structure comprising a silicon nitride light waveguide on a substrate; processing the structure for forming the photonic circuit; wherein the processing of the structure comprises the structure being exposed to electromagnetic radiation having an energy sufficiently large to excite electrons to a conduction band in the silicon nitride light waveguide; the method further comprising exposing the silicon nitride light waveguide to a charge carrier exciting condition for exciting electrons from charge traps in the silicon nitride light waveguide to a conduction band and electron holes from charge traps in the silicon nitride light waveguide to a valence band for depopulating charge traps so as to reduce propagation loss of light through the silicon nitride light waveguide wherein the exposing of the silicon nitride light waveguide to the charge carrier exciting condition comprises illuminating the structure with light having an energy larger than an energy difference between a charge trap energy level and a conduction band energy level or a valence band energy level, the light having an energy smaller than a material bandgap in the silicon nitride light waveguide; or wherein the exposing of the silicon nitride light waveguide to the charge carrier exciting condition comprises transmitting light through the light waveguide, wherein the light has an energy larger than an energy difference between a charge trap energy level and a conduction band energy level or a valence band energy level, the light having an energy smaller than a material bandgap in the silicon nitride light waveguide; or wherein the exposing of the silicon nitride light waveguide to the charge carrier exciting condition comprises exposing the structure to a temperature in a range of 150-400°C.