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Field emission devices are promising candidates to replace silicon FinFETs as nextgeneration nanoelectronic components. For these devices to be adopted, nanoscale field emitters with nanoscale gaps between them need to be fabricated, requiring the transfer of e.g. sub-10 nm patterns with sub-20 nm pitch into substrates like silicon and tungsten. New resist materials must therefore be developed that exhibit the properties of sub-10 nm resolution and high dry etch resistance. A negative tone, metal-organic resist is presented here. It can be patterned to produce sub-10 nm features when exposed with helium ion beam lithography at line doses on the order of 10s of pC/cm. The resist was used to create 5 nm wide, continuous, discrete lines spaced on a 16 nm pitch in silicon, and 6 nm wide lines on 18 nm pitch in tungsten, with line edge roughness of 3 nm. After the lithographic exposure, the resist demonstrates high resistance to silicon and tungsten dry etch conditions (SF 6 and C 4 F 8 plasma), allowing the pattern to be transferred into the underlying substrates. The resist's etch selectivity for silicon and tungsten was measured to be 6.2:1 and 5.6:1, respectively; this allowed 3-4 nm thick resist films to yield structures that were 21 and 19 nm tall, respectively, while both maintained sub-10 nm width on sub-20 nm pitch.

An InGaAsP-InP optical switch geometry based on electrical control of waveguide-resonator coupling is demonstrated. Thermooptic tuning of a Mach-Zehnder interferometer integrated with a racetrack resonator is shown to result in switching with ON-OFF contrast up to 18.5 dB. The optical characteristics of this unique design enable a substantial reduction of the switching power, to a value of 26 mW in comparison with 40 mW for a conventional Mach-Zehnder interferometer switch. Modulation response measurements reveal a 3 dB bandwidth of 400 kHz and a rise time of 1.8 µs, comparing favorably with current state-of-the-art thermooptic switches.

We demonstrate single-mode lasing at telecommunication wavelengths from a circular nanocavity employing a radial Bragg reflector. Ultrasmall modal volumes and submilliwatt pump thresholds level are observed for lasers with InGaAsP quantum well active membrane. The electromagnetic field is shown to be tightly confined within the 300 nm central pillar of the cavity. The quality factors of the resonator modal fields are estimated to be on the order of a few thousands. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.1947375͔The quest for the ultimate localization of light has been one of the central directions in contemporary research in many fields, such as integrated optics, quantum communication and computation, sensing, and more. 1-3 Optical nanocavities with high-quality factors ͑Q͒ and small modal volume ͑V mode ͒ are key elements for a wide variety of applications, such as functional building blocks for integrated optical circuits, lasers, optical traps, and optical logic. 4,5 In the past few years, much attention was focused on decreasing the modal volume and improving the Q of photonic crystal ͑PC͒ defect cavities by carefully optimizing the position, dimensions, and shape of the holes composing the crystal. [6][7][8][9] This optimization procedure attempts to tune the effective length of the cavity to the maximal reflection frequency of the PC reflector and is generally conducted numerically. The main disadvantage of this process is the enormous number of parameters to be optimized and the endless number of configurations that potentially need to be considered.Recently, we have proposed and demonstrated a novel class of circular resonators that are based on optimally designed radial Bragg reflectors. 9-11 These devices, known as annular Bragg resonators ͑ABRs͒, are designed to support azimuthally propagating modes, with energy concentrated within a radial defect region or in a central pillar by radial Bragg reflection. Compared to conventional resonators based on total-internal reflection ͑TIR͒, the employment of the Bragg reflection mechanism offers improved control over the resonator parameters ͑Q, V mode , etc.͒ and allows for engineering unique mode profiles. Compared to PC defect resonators, the radial symmetry of ABRs allows for analytical engineering the Bragg reflector for optimized Q and smaller modal volume. These properties make the ABR structure highly suitable for realizing ultracompact cavities, especially if they are designed for the mode with angular modal number m = 0. The m = 0 mode is an interesting solution of a disk Bragg resonator consisting of a disk surrounded by a radial Bragg stack ͑see Fig. 1͒. Unlike other solutions with nonzero angular modal numbers, the m = 0 mode is nondegenerate and features maximum intensity at the center of the device. This mode cannot be supported in conventional cavities because the propagation direction of the waves is perpendicular to the cavity interfaces.In this letter, we report on the observation of single mode lasing from a Bragg-based dis...

Abstract-A novel class of circular resonators, based on a radial defect surrounded by Bragg reflectors, is studied in detail. Simple rules for the design and analysis of such structures are derived using a transfer matrix formalism. Unlike conventional ring resonators, annular Bragg resonators (ABR) are not limited by the total internal reflection condition and can exhibit both large free spectral ranges and low bend losses. The Bragg reflection mechanism enables the confinement of light within a defect consisting of a low refractive index medium (such as air). Strong atom-photon interaction can be achieved in such a structure, making it a promising candidate for sensing and cavity quantum electrodynamics applications. For sensing applications, we show that the ABR structure can possess significantly higher sensitivity when compared to a conventional ring resonator sensor. Lasing action and low threshold levels are demonstrated in ABR lasers at telecommunication wavelengths under pulsed optical pumping at room temperatures. The impact of the intensity and dimensions of the pump spot on the emitted spectrum is studied in detail.