Recent progresses on metamaterials for optical absorption and sensing: a review

Metamaterials (MMs) offer great potential for achieving optical absorption due to their novel electromagnetic properties. MM absorbers can overcome the thickness limitation and provide excellent absorption performance over the wide frequency range, thereby enable the swift emergence of some promising applications. Moreover, the optical sensors based on MM absorbers have shown great potential in several fields. This review concentrates on the recent progresses in MM-based optical absorbers and spectral sensing. We present four aspects of MM-based optical absorption: the metal-insulation-metal arrangements, the optical coherence, the functional materials, and some novel approaches. Also, we present three aspects of MM-based optical sensing: the refractive index sensing, gas and molecule sensing, and surface-enhanced Raman scattering. Finally, the current challenges and prospects in device designs, fabrications have been discussed. This review is with the purpose to give a generalized knowledge of MMs for optical absorption and sensing, thus inspiring the investigations on MMs for other devices and their practical applications. (topical review)