Integrated optical device with phosphor in substrate pit

Apparatus comprising, in combination:

• a passive integrated optical waveguide segment;
• a phosphor disposed to receive optical energy from said waveguide segment, at least a portion of said phosphor being located in a common plane with said waveguide segment and re-radiating optical energy in response to optical energy received from said waveguide segment;
• and
• a reflector disposed to reflect away from said common plane, optical energy re-radiated by said phosphor.

A substrate supporting:

• an integrated optical waveguide segment confining optical energy in at least one dimension, said waveguide segment having a core and said optical energy having a propagation axis;
• a pit disposed in said substrate to receive optical energy from said waveguide segment;
• and
• an upconversion optical re-radiator disposed in said pit, said re-radiator having a maximum size, in a first dimension perpendicular to said propagation axis, which is larger than the size of said core in said first dimension.