Reduced ASE threshold from aperiodic photonic structures in rhodamine B-doped king salmon (oncorhynchus tshawytscha) iridophores

Abstract

The broadband reflectance of iridescent silvery fish is caused by aperiodic photonic structures formed by complex distributions of guanine platelets in their iridophores. Photons can be reflected multiple times inside the iridophores found in many pelagic teleosts allowing for advanced photonic methods of characterization. The one-dimensional aperiodic structures reflect light over a broad spectrum. Enhanced amplified spontaneous emission (ASE) and suppressed laser light in stained skin tissue is attributed to the high group velocities and negligible localization of light over the gain envelope of rhodamine B (RhB). The enhancement to the ASE, reported herein, is shown to be caused by an increase in the effective ASE gain path length of photons generated in the iridophores of skin tissue stained with RhB. We show that the effective ASE gain path length can be used as a figure-of-merit to quantify aperiodic photonic structures, including those found in many underwater animals, by determining the increase of a photon's average time spent in broadband reflective tissue.