High quality factor polymeric Fabry-Perot resonators utilizing a polymer waveguide

Abstract

Optical resonators are used in a variety of applications ranging from sensors to lasers and signal routing in high volume communication networks. Achieving a high quality (Q) factor is necessary for higher sensitivity in sensing applications and for narrow linewidth light emission in most lasing applications. In this work, we propose a new approach to achieve a very high Q-factor in polymeric Fabry-Perot resonators by conquering light diffraction inside the optical cavity. This can be achieved by inducing a refractive index feature inside the optical cavity that simply creates a waveguide between the two mirrors. This approach eliminates diffraction loss from the cavity and therefore the Q-factor is only limited by mirror loss and absorption. To demonstrate this claim, a device has been fabricated consisting of two dielectric Bragg reflectors with a 100 μm layer of photosensitive polymer between them. The refractive index of this polymer can be modified utilizing standard photo-lithography processes. The measured finesse of the fabricated device was 692 and the Q-factor was 55000.