Ultra-large tuning of photonic modes for efficient Er-doped silicon-based emitters

► We report the tuning of resonant modes in a silicon based photonic crystal slab. ► We obtained a shift of 42nm by means of a gas condensation technique. ► Strong enhancement of the emission band of the Er3+ ion is observed. ► We achieved a stable mode at a desired wavelength varying the temperature. We demonstrate that a gentle gas adsorption technique can be used to achieve an optimal covering of silicon-based photonic crystal slabs, leading to an unexpectedly large (up to 42nm) shift of the resonant modes wavelength, with possibility of fine tuning. Strong enhancement (up to 30 times) of the emission band of the Er3+ ion into such structures is obtained. Finally, we were able to balance the adsorption and desorption processes by controlling the sample temperature, thus yielding a stable mode at the desired wavelength.