Purcell-enhanced emission from a coupled emitter-cavity system is a
fundamental manifestation of cavity quantum electrodynamics. Starting from a
theoretical description we derive a scheme for photon emission from an emitter
coupled to a birefringent cavity that exceeds hitherto anticipated limitations.
Based on a recent study and experimental investigation of the intra-cavity
coupling of orthogonal polarisation modes in birefringent cavities, we now
decouple the emitter and the photon prior to emission from the cavity mode.
Effectively, this is "hiding" the emitter from the photon in the cavity to
suppress re-excitation, increasing the overall emission through the cavity
mirrors. In doing so we show that tailored cavity birefringence can offer
significant advantages and that these are practically achievable within the
bounds of present-day technology. It is found that birefringence can mitigate
the tradeoff between stronger emitter-cavity coupling and efficient photon
extraction. This allows for longer cavities to be constructed without a loss of
performance -- a significant result for applications where dielectric mirrors
interfere with any trapping fields confining the emitter. We then generalise
our model to consider a variety of equivalent schemes. For instance, detuning a
pair of ground states in a three-level emitter coupled to a cavity in a
Lambda-system is shown to provide the same enhancement, and it can be combined
with a birefringent cavity to further increase performance. Additionally, it is
found that when directly connecting multiple ground states of the emitter to
form a chain of coupled states, the extraction efficiency approaches its
fundamental upper limit. The principles proposed in this work can be applied in
multiple ways to any emitter-cavity system, paving the way to surpassing the
traditional limits of such systems with technologies that exist today.Comment: 8 pages, 8 figures plus 3 page appendi
