Entry Date:
August 25, 2015

QA/TEST Design and Manufacture of Bio-Inspired Light-Emitting Optical Micro-Cavities

Principal Investigators Mathias Kolle , Sanjay Sarma

Co-investigators Mathias Kolle , Sanjay Sarma

Project Website https://mit.edu

Project Start Date January 2017

Project End Date
 September 2017


Optical micro-cavities are structures confining light in a small volume by resonant circulation. They can be constructed from two reflective surfaces sandwiching a gain medium to create light-emitting devices and lasers. The quality factor, representing the ratio between the number of round trips that a photon takes in the cavity and the cavity losses, determines the maximum attainable light amplification.

We design and manufacture optical micro-cavities containing light-emitting organic dyes, which were inspired by a structure found on the wings of the Papilio blumei butterfly. In the micro-cavities described here, individual reflectors consist of concave half-spherical metal surfaces with 1 ?m-to-10 ?m diameter topped by a Bragg reflector. Given their micro-scale dimensions, the cavities support a variety of optical resonances in the visible spectrum. The cavities’ bottom reflector is formed from gold or silver with broadband reflectivity. The second light-confining mirror, a flat Bragg reflector, provides high reflectivity for a selected spectral range. The amplifying medium consists of an organic dye stabilized in a polymer matrix. 

The manufacturing of the micro-cavities combines a set of procedures, including the assembly of a colloidal template, the formation of cavities by electro-deposition of metal in the template’s interstitial spaces, template removal, solvent-based spin-casting of the organic dye, and the creation of a Bragg reflector using chemical vapor deposition. The cavities represent periodically arranged micro-scale light sources with potential to be selectively switched on and off. Furthermore, they show interesting optical behaviors such as spectral selectivity, polarization rotation effects, and emission in a broad range of angles. The cavities will be incorporated into microfluidic devices and lab-on- chip assemblies to provide localized chemical sensing and precise cell imaging for applications in microbiology.