Microphotonics to nanophotonics: A quick scan

The era of microphotonics started with passive integrated optics consisting of 2D and 3D (channel) waveguides on transparent substrates which exhibit electrooptic, acoustooptic, magnetooptic, thermooptic and other special properties. In 2D waveguides, light is confined to a two-dimensional plane on the surface of the substrate where the refractive index is slightly greater than that of the bulk. In recent years, new revolutionary concepts have changed the nature of photonic devices and systems. The first is the photonic crystal or photonic bandgap material. The second is the surface plasmon polariton (SPP)-based integrated optics. In both these cases, the minimum feature size of device structure has shrunk to nanometer scale. Simultaneously, highly quantum efficient lasers and detectors have also been developed using quantum wells and quantum dots featuring 1-10 nm structures. This new class of photonic and optoelectronic devices is categorised as nanophotonics.