Insight into planar microcavity emission as a function of numerical aperture

Abstract

This paper develops a semi-empirical model to investigate the spectral properties of planar microcavities as a function of the observation numerical aperture (NA). The development of the model clearly highlights the fundamental principles of planar microcavity emission which are therefore applicable to resonant cavity light emitting diode (RCLED) structures in general. In the present work, we clearly identify features of planar microcavity emission that are often overlooked in the literature, namely, an increase in line width with NA (by a factor of 3 in the present samples) and the peak shift of the central emission wavelength as a function of NA and detuning. The analysis identifies an intrinsic shift in peak emission wavelength over the observation NA which is attributed to a planar microcavity's preference for off-axis emission. It is clear the spectral properties of planar microcavities are explicitly dependent on NA highlighting the importance of well-defined coupling optics in the design of optical systems incorporating RCLEDs.