Intellectual Merits: The key innovation in this research is the development of synthetic optical materials with desired dispersive and diffractive properties through optimal dispersion engineering in PCs. This will be enabled by combining multiple unique dispersive properties of PCs in a single structure. The optimal dispersion engineering will allow for the development of novel microspectrometers and PC interferometers with excellent performance for sensing, despite having dimensions in the order of only a few hundred microns. The complete integrated spectrometer module is realized by optimal integration of these different functionalities (superprism-based spectrometers and PC interferometers) in a single substrate through the addition of optimal mode converters (or matching stages). Such heterostructure PCs will offer the best solution to the everincreasing demand for integrated chip-scale spectroscopy, especially for sensing applications. The expected performance improvement (accuracy in spectral feature detection, size of the structure, etc.) over existing implementations of the PC spectrometers will be 1-2 orders of magnitude.
Broader Impacts: While the focus in this proposal is the development of ultra-compact on-chip spectrometers, the results of the two major tasks proposed here will be beneficial for other applications as well. For example, the use of the second PC band can dramatically improve the performance of the PC wavelength demultiplexers for which the findings of this research can be used with some modifications during optimization. Another example is the use of PC interferometers directly for sensing applications in which the presence of the analyte of interest changes the output spatial-spectral pattern, which can be measured and used for the estimation of the properties of the analyte. The photonic crystal structures as defined in this proposal have the prospect of creating a revolution in on-chip optical sensing systems. The concept of dispersion engineering in PCs can be extended to three-dimensional (3D) PC structures for the development of compact devices for free-space optics applications.
