Biomaterials offers opportunities to design compact and coherent light sources applicable to biological sensing and imaging applications due to the biocompatibility of the devices. To date, conventional techniques have been adopted to design biological light sources such as planar microcavity laser, microspheres, distributed feedback lasers and random lasers (RLs). Among those RLs are easy to fabricate by the random distribution of scatterers in a gain medium to achieve amplified gain and coherent lasing. Here, we report a fully biocompatible light source exhibiting RLs and low threshold amplified spontaneous emission (ASE). A favorable combination of a silk inverse opal (SIO) with the inherent disorder and sodium fluorescein a biocompatible optical gain incorporated into a silk protein film induces random cavities. An inverse opal of proper diameter with optical gain forms high Q random cavities due to refractive index modulation induced by the structural imperfections, which induced gain enhancement to show low threshold ASE and distinguishable coherent RLs spikes. Also, high surface-to-volume ratio and the trait of amplification of the SIO led to highly efficient chemosensing to detect the HCl vapor.
Furthermore, SIO can have a form of microparticles. Lasing from the SIO powder under a plant tissue is demonstrated as a proof-of-concept experiment for applicability of the prepared RL under biological surfaces as a tissue engineering biological device. Our finding opens upon new ways to develop compact size bio-lasers.