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In our continuous variable quantum key distribution (QKD) scheme, the homodyne detection set-up requires balancing the intensity of an incident beam between two photodiodes. Realistic lens systems are insufficient to provide a spatially stable focus in the presence of large spatial beam-jitter caused by atmospheric transmission. We therefore present an improved geometry for optical tapers which offer up to four times the angular tolerance of a lens. The effective area of a photodiode can thus be increased, without decreasing its bandwidth. This makes them suitable for use in our free space QKD experiment and in free space optical communication in general.
Free-space optical communication is a promising means to establish versatile, secure and high-bandwidth communication for many critical point-to-point applications. While the spatial modes of light offer an additional degree of freedom to increase th
The orbital angular momentum (OAM) of photons presents a degree of freedom for enhancing the secure key rate of free-space quantum key distribution (QKD) through mode-division multiplexing (MDM). However, atmospheric turbulence can lead to substantia
An optical buffer having a large delay-bandwidth-product -- a critical component for future all-optical communications networks -- remains elusive. Central to its realization is a controllable inline optical delay line, previously accomplished via en
Free-electron beams serve as uniquely versatile probes of microscopic structure and composition, and have repeatedly revolutionized atomic-scale imaging, from solid-state physics to structural biology. Over the past decade, the manipulation and inter
In this paper, we employ an antireflective coating which comprises of inverted pi shaped metallic grooves to manipulate the behaviour of a TM-polarized plane wave transmitted through a periodic nanoslit array. At normal incidence, such scheme can not