Dmitry A. Kozak

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We detect trace gases at parts-per-billion levels using evanescent-field absorption spectroscopy in silicon nitride microring resonators coated with a functionalized sorbent polymer. An analysis of the microring resonance line shapes enables a measurement of the differential absorption spectra for a number of vapor-phase analytes. The spectra are obtained(More)
We demonstrate an integrated waveguide platform and optomechanical transduction circuit for chip-scale displacement sensing. The waveguide consists of a thin silicon nitride core layer, a thick silicon oxide bottom cladding, and a top air cladding with a large evanescent field at the waveguide surface. Although the structures feature subwavelength(More)
Photonic integrated circuits have enabled progressively active functionality in compact devices with the potential for large-scale integration. To date the lowest loss photonic circuits are achieved with silica or silicon nitride-based platforms. However, these materials generally lack reconfigurability. In this work we present a platform for achieving(More)
The Mid-wave infrared (MWIR) spectrum has applications to many fields, from night vision to chemical and biological sensors. Existing broadband detector technology based on HgCdTe allows for high sensitivity and wide range, but lacks the spectral decomposition necessary for many applications. Combining this detector technology with a tunable optical filter(More)
An optically coherent silicon-on-insulator circuit for microwave phase shifting is presented. Such photonic integrated circuits provide advantages over more-complicated incoherent methods and coherent techniques implemented in bulk fiber-optic components. The circuit is described theoretically with supporting experimental data. Continuous microwave phase(More)
Fabrication of nanoscaled transistors based on carbon nanotubes and inorganic nanowires is typically demonstrated with a “pick-and-place” or similar method which allows for fabrication of small numbers of transistors at a time. While these, and other, devices have been used to demonstrate potential applications of carbon nanotubes, these methods are not(More)
We demonstrate a new device architecture enabling large effective index tuning in a highly-evanescent waveguide interacting with a suspended microbridge. Using gradient electric forces, we actuate the microbridge to induce dynamic phase shifts Δφ>π at low electrical power.
This article describes recent research at the U.S. Naval Research Laboratory that focuses on the use of micro- and nanomachining techniques for photonic waveguide devices. By selectively etching a sacrificial layer that the waveguide core is supported by, in whole or in part, the waveguide obtains enhanced properties and functionality, such as mechanical(More)