Recent developments in integrated spectrometers

In the 1990s, the Institute for Microstructural Sciences has maintained a research project on wavelength division multiplexing (WDM) based on integrated echelle gratings spectrometers. Major obstacles to the application of these spectrometers to telecommunications, such as channel wavelength accuracy, insertion loss, birefringence, polarisation dependent loss, compliance to flat band, and crosstalk, have been largely resolved. This technology has been transferred to the industry and our current efforts concentrate on integrated spectrometers in high index contrast waveguides. This paper reviews the advances in the echelle grating demultiplexers and in the miniaturisation of arrayed waveguide grating (AWG) spectrometers.