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We propose a way to engineer the design of photonic molecules, realized by coupling two photonic crystal cavities, that allows an accurate control of the parity of their ground states. The spatial distribution of the fundamental mode of photonic molecules can be tuned from a bonding to an antibonding character by a local and continuous modification of the dielectric environment in between the two coupled cavities. In the systems that we investigate the transition could be experimentally accomplished by post-fabrication methods in either a reversible or an irreversible way. We notably find that the mode parity exchange is tightly related to a dramatic variation of the far field emission pattern, leading to the possibility to exploit these systems and techniques for future applications in optoelectronics.

The effect of periodic and disordered photonic structures on the absorption efficiency of amorphous and crystalline Silicon thin-film solar cells is investigated numerically. We show that disordered patterns possessing a short-range correlation in the position of the holes yield comparable, or even superior, absorption enhancements than periodic (photonic crystal) patterns. This work provides clear evidence that non-deterministic photonic structures represent a viable alternative strategy for photon management in thin-film solar cells, thereby opening the route towards more efficient and potentially cheaper photovoltaic technologies.

We propose a time-dependent, spatially periodic photonic structure which is able to shift the carrier frequency of an optical pulse which propagates through it. Taking advantage of the slow group velocity of light in periodic photonic structures, the wavelength conversion process can be performed with an efficiency close to 1 and without affecting the shape and the coherence of the pulse. Quantitative Finite Difference Time Domain simulations are performed for realistic systems with optical parameters of conventional silicon technology.