Ultra‐Wide Modulation and Reversible Reconfiguration of a Flexible Organic Crystalline Optical Waveguide Between 645 and 731 nm

Abstract Flexible organic crystalline optical waveguides, which deliver input or self‐emit light through various dynamic organic crystals, have attracted increasing attention in the past decade. However, the modulation of the waveguide output relies on chemical design and substituent modification, being time‐consuming and laborious. Here we report an elastic organic crystal that displays long‐distance light transduction up to 2.0 cm and an ultra‐wide modulation of crystalline optical waveguides between red (645 nm) and near infrared (731 nm) in both the pristine and the elastically bent states based on a pre‐designed self‐absorption effect. The flexible organic crystalline optical waveguides can be precisely and reversibly reconfigured by controlling the irradiation point. In addition, deep‐red amplified spontaneous emission (ASE) that is able to transduce through a 5.0 mm bent crystal with an ultra‐low optical loss coefficient of 0.093 dB/mm has been attained. To the best of our knowledge, this is the first report of flexible organic ASE waveguides. The present study not only provides a simple yet effective strategy to remarkably modulate flexible organic crystalline optical waveguides but also demonstrates the superiority of lasing over normal emission as flexible optical communication elements.