Widely Tuning Surface Plasmon Polaritons with Laser‐Induced Bubbles

The wide‐range tunable all‐optical plasmonic devices are of importance for the multifunctional photonic circuits of high densities. Here, the laser‐induced bubbles are utilized to widely tune the surface plasmon polaritons (SPPs) in the metallic hole array. Because of the bubbles generation under a pump beam, the equivalent refractive index of the dielectric medium adjacent to the metal surface decreases. This decrease blue‐shifts the transmission spectrum of the hole array. Experimentally, a modulation depth of 18 dB below the critical pump intensity and an index variation of Δn = −0.333 corresponding to a wavelength shift of about Δλ = −200 nm above the critical pump intensity are achieved. Moreover, the transmission intensity at λ = 870 nm can be tuned to cover the whole range from the peak intensity to the valley intensity of the hole array by controlling the size of the bubble. Such a large index variation (Δn = −0.333) and wavelength change (Δλ ≈ −200 nm) can greatly decrease the designing difficulty of the tunable plasmonic devices. Thus, the laser‐induced bubbles under low pump intensities may find important applications, such as efficient modulating as well as tunable color filter, focusing, and imaging with broadband responses.