Daniel Headland

The terahertz range possesses significant untapped potential for applications including high-volume wireless communications, noninvasive medical imaging, sensing, and safe security screening. However, due to the unique characteristics and constraints of terahertz waves, the vast majority of these applications are entirely dependent upon the availability of beam control techniques. Thus, the development of advanced terahertz-range beam control techniques yields a range of useful and unparalleled

Advances in terahertz technology rely on the combination of novel materials and designs. As new devices are demonstrated to address the terahertz gap, the ability to perform high-efficiency beam control will be integral to making terahertz radiation a practical technology. Here, we use a metasurface composed of nonuniform dielectric resonator antennas on a ground plane to achieve efficient beam focusing at 1 THz. The dielectric resonators are made of high-resistivity silicon, which is a low-loss

Recent years have seen the emergence of efficient, general-purpose terahertz photonic-crystal waveguides etched from high-resistivity silicon. Systems founded upon this platform will require antennas in order to interface with free-space fields. Multi-beam antennas are desirable to this end, as they are capable of interacting with a number of distinct directions simultaneously. Such functionality can be provided by Luneburg lenses, which we aim to incorporate with the terahertz photonic crystal

A practical approach to realize substrateless, unclad, micro-scale intrinsic silicon waveguides for the terahertz range is presented. The waveguides are monolithically integrated within a supporting silicon frame, with which they are fabricated together from the same silicon wafer in a single-mask etching process. This establishes an integration platform to house many diverse components and facilitates packaging. Effective medium techniques are deployed to prevent the frame from interfering with

Single-crystal silicon is bonded to a metal-coated substrate and etched in order to form an array of microcylinder passive terahertz dielectric resonator antennas (DRAs). The DRAs exhibit a magnetic response, and hence the array behaves as an efficient artificial magnetic conductor (AMC), with potential for terahertz antenna and sensing applications.

We demonstrate a terahertz flat lens based on tri-layer metasurfaces allowing for broadband linear polarization conversion, where the phase can be tuned through a full 2π range by tailoring the geometry of the subwavelength resonators. The lens functionality is realized by arranging these resonators to create a parabolic spatial phase profile. The fabricated 124-μm-thick device is characterized by scanning the beam profile and cross section, showing diffraction-limited focusing and ∼68% overall

This paper covers our recent work on terahertz reflectarray antennas, providing a broad, critical perspective, and contrasting different approaches. The reflectarray antenna is a well-established device that offers significant control and freedom over the directionality and characteristics of its radiation pattern. Such a capability is critical to the successful development of commercially viable terahertz technologies. In this paper, the design, fabrication, and experimental characterization of

The arrayed waveguide grating (AWG) is a versatile and scalable passive photonic multiplexer that sees widespread usage. However, the necessity of a waveguide array engenders large device size, and gratings invariably commute finite power into undesired diffraction orders. Here, we demonstrate AWG-like functionality without a grating or waveguide array, yielding benefits to compactness, bandwidth, and efficiency. To this end, we exploit optical tunneling from a dielectric waveguide to an adjacen

The absence of a suitable standard device platform for terahertz waves is currently a major roadblock that is inhibiting the widespread adoption and exploitation of terahertz technology. As a consequence, terahertz-range devices and systems are generally an ad hoc combination of several different heterogeneous technologies and fields of study, which serves perfectly well for a once-off experimental demonstration or proof-of-concept, but is not readily adapted to real-world use case scenarios. In

Terahertz technology is being accelerated by photonic crystal waveguides that are implemented with an array of through-holes in an intrinsic silicon slab. Such waveguides show promise to realize compact terahertz systems. However, photonic crystal waveguides were originally developed in the infrared range, where small relative bandwidth is acceptable for communications applications. Greater relative bandwidth is desirable for the lower-frequency terahertz range, and hence our aim is to increase

Currently, optics such as dielectric lenses and curved reflector dishes are commonplace in terahertz laboratories, as their functionality is of fundamental importance to the majority of applications of terahertz waves. However, such optics are typically bulky and require manual assembly and alignment. Here we seek to draw inspiration from the field of digital electronics, which underwent rapid acceleration following the advent of integrated circuits as a replacement for discrete transistors. For

We present a paradigm for integrated photonic devices based on broadband slab-confined collimated beams that are launched with half-Maxwell fisheye lenses. Although it is challenging to match to the low-index focus of the lens while maintaining adequate field confinement for a close approximation of a point source, integrated dielectric slot waveguides prove highly suitable, yielding collimators of 90% efficiency and bandwidth greater than one octave. Terahertz technology will benefit from such

The dielectric properties of an elastomeric polymer are modified with the inclusion of dopants, with the aim of reducing dielectric loss in the terahertz range. Polydimethylsiloxane (PDMS) is selected as the host polymer, and micro/nano-particle powders of either alumina or polytetrafluoroethylene (PTFE) are employed as dopants. Composite samples are prepared, and characterised with terahertz time-domain spectroscopy (THz-TDS). The samples exhibit significantly reduced dielectric loss, with a ma

Terahertz-range photonic crystal waveguides composed of intrinsic silicon are showing promise as an efficient and versatile waveguiding platform for diverse applications. Compact terahertz systems that are founded upon this platform will benefit from near-field links in order to serve as general-purpose connectors and allow devices to be modular. To this end, we present near-field contactless signal power transfer between terahertz-range photonic crystal waveguides in the out-of-plane dimension.

There is a need to reduce the cost and size of functional terahertz devices, in order to expedite this notoriously underutilized frequency band toward practical applications. Electronic integrated circuits (ICs) are extremely useful to this end, as they provide a means to achieve miniaturization and mass production, leveraging the foundries and techniques that have made digital electronics ubiquitous. Although integration of terahertz systems is expected to diminish performance and functionality