Fabrication of gold nanorods absorption layers for infrared sensors

We report a new approach for very thin infrared absorption layers consisting of gold nanorods. By using a modified seeding growth process we were able to prepare gold nanorods with an aspect ratio of up to 50. These nanorods have a typical length of 1,154 plusmn 111 nm and an average diameter of 26 plusmn 4 nm. They showed a longitudinal surface plasmon resonance absorption band at about 4,634 nm which is situated in the mid-wave infrared (MWIR) range. According to this, an enhancement in the responsivity of pyroelectric single element detectors could be observed verifying the functionality of the gold nanorods absorption layer. The position of the absorbance maximum can be easily controlled by the aspect ratio of the gold nanorods.