Photonic crystals microcavities (PCMCs) design allow to realize optical modes with large quality factor which have been already successfully exploited for the realization of low-threshold lasers, single photon sources, add-drop filters, and for the implementation of cavity quantum electrodynamics experiments.
In this talk I will review recent results obtained in Florence on three crucial issues in the progress of photonic crystal microcavities (PCMCs).
1) Imaging the optical local density of states (LDOS) of PCMCs  by using the tip-induced modifications of the PCMC modes by scanning near-field optical microscopy (SNOM). Mapping of the magnetic field has also been achieved by using a metallic coated tip .
2) Tuning the optical resonances in PCMCs. Three different approaches to the local and reversible tuning have been realized. i) Water micro-infiltration, at the level of the PC single pore . ii) local evaporation of the infiltrated water  iii) Laser induced nano-oxidation .
3) Coupling the optical modes of adjacent PCMCs via evanescent waves. The photonic
coupling of two closely spaced PC-MCs have been demonstrated and by means of near field imaging . Control of the cavity detuning is obtained by locally tuning a single cavity mode . Anticrossing and mode hybridization is found .
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