Abstract
Systems with coupled cavities and waveguides have been demonstrated as optical switches and optical sensors. To optimize the functionalities of these optical devices, Fano resonance with asymmetric and steep spectral line shape has been used. We theoretically propose a coupled photonic crystal cavity-waveguide structure to achieve Fano resonance by placing partially reflecting elements in waveguide. To enhance Fano resonance, optical gain material is introduced into the cavity. As the gain increases, the transmission line shape becomes steepened and the transmissivity can be six times enhanced, giving a large contrast by a small frequency shift. It is prospected that the gain enhanced Fano resonance is very useful for optical switches and optical sensors.
Highlights
Systems with coupled cavities and waveguides have been demonstrated as optical switches and optical sensors
The interaction between light and matter can be greatly enhanced, which is important for investigations of cavity quantum electrodynamics[1,3,4,5]
We introduce gain material into the Photonic crystal (PhC) cavity to enhance the Fano resonance
Summary
Coupled PhC H1 cavity and waveguide structure. We employed a free-software package MEEP27 to design the PhC structure. To realize Fano resonance, partially reflecting elements are introduced into the coupled PhC cavity-waveguide structure. When the waveguide modes are non-resonant with the cavity modes, the light can not be coupled into the cavity and is reflected mostly by the two air hole barriers. In our coupled PhC cavity-waveguide structure (shown in Fig. 3(a)), gain material is located at the center of the H1 cavity with a radius of 0.6 a and thickness of 0.6 a. Without gain material in the cavity, the normalized transmissivity corresponding to the degenerated quadrupole modes is 0.246. The resonant mode can be perturbed if there are nano-particles adhere to the H1 cavity, which gives a frequency shift in the transmission spectrum. The narrow and steep Fano asymmetric transmission lineshape could make the coupled structure much more attractive as a nano-particle sensor[31]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
