Photonic Crystal Waveguides

The original results of theoretical and experimental studies and the properties of microwave one-dimensional waveguide photonic crystals have been generalized. Methods for describing the electrodynamic characteristics of photonic crystals and their relationship with the parameters of periodic structures filling the waveguides have been presented. The results of an investigation on the characteristics of microwave waveguide photonic crystals made in the form of dielectric matrices with air inclusions have been presented. The model of effective dielectric permittivity has been proposed for describing the characteristics of the investigated photonic crystals containing layers with a large number of air inclusions. New types of microwave low-dimensional waveguide photonic crystals containing periodically alternating elements that are sources of higher type waves have been described. The possibility of effective control of the amplitude-frequency characteristics of microwave photonic crystals by means of electric and magnetic fields has been analyzed. Examples of new applications of waveguide photonic crystals in the microwave range have been given: the measuring parameters of the materials and semiconductor nanostructures that play the role of the microwave photonic crystals\u27 periodicity defect; the resonators of near-field microwave microscopes; small-sized matched loads for centimeter and millimeter wavelength ranges on the basis of microwave photonic crystals

Resonances in the "post with gap—adjacent piston" waveguide system

The electrodynamic system composed of a metal post with a gap and a short-circuiting piston located nearby is investigated theoretically and experimentally. It is shown that such a system can be used successfully in designing small-size microwave devices, whose characteristics are controlled by magnetic field

A rectangular resonator with its characteristics controlled by magnetic field

The paper shows that in microwave systems made of nonmagnetic materials, in which the conditions for resonance are established, we can observe a strong dependence of their electrodynamic characteristics on the applied magnetic field. The dependence arises from the Hall component of the microwave current flowing in the internal semiconductor insertions and in metal walls of the resonator

Formation of Five- and Seven-Membered Rings Enabled by the Triisopropylsilyl Auxiliary Group

A highly convenient synthetic pathway to 2-indanones from aldehydes was established. The introduction of a triisopropylsilyl group greatly facilitated Meinwald rearrangement of the intermediate epoxides and alleviated the necessity of polysubstitution for the clean formation of indenes and cyclopentadienes via cyclodehydration of allylic alcohols; unprecedented freedom with respect to the product structure was thus achieved. The developed methodology could also be applicable to the formation of seven-membered rings leading to dibenzo[7]annulenes and dibenzosuberones

Microstrip PIN diode microwave switch

A possibility of creating narrow-band electrically controlled microwave breakers and switches with enhanced attenuation level in the blocking mode has been considered. The specified devices are based on the structure containing a short-circuited microstrip link with connected capacitor and the loop coupler, in the center of which is located a PIN diode

A high-Q low-dimensional resonator with electrically tunable frequency

A low-dimensional high-Q resonator has been proposed and its frequency-response characteristics have been investigated. The specified resonator features the frequency-response characteristics that are electrically tunable by using a semiconductor diode with variable capacitance

Optical Characterization of AsxTe100−x Films Grown by Plasma Deposition Based on the Advanced Optimizing Envelope Method

Three AsxTe100−x films with different x and dissimilar average thickness d ¯ are characterized mainly from one interference transmittance spectrum T(λ = 300 to 3000 nm) of such film on a substrate based on the advanced optimizing envelope method (AOEM). A simple dual transformation of T(λ) is proposed and used for increasing the accuracy of computation of its envelopes T+(λ) and T−(λ) accounting for the significant glass substrate absorption especially for λ > 2500 nm. The refractive index n(λ) of As40Te60 and As98Te2 films is determined with a relative error <0.30%. As far as we know, the As80Te20 film is the only one with anomalous dispersion and the thickest, with estimated d ¯ = 1.1446 nm, ever characterized by an envelope method. It is also shown and explained why the extinction coefficient k(λ) of any of the three AsxTe100−x films is computed more accurately from the quantity Ti(λ) = [T+(λ)T−(λ)]0.5 compared to its commonly employed computation from T+(λ). The obtained results strengthen our conviction that the AOEM has a capacity for providing most accurate optical characterization of almost every dielectric or semiconductor film with d ¯ > 300 nm on a substrate, compared to all the other methods for characterization of such films only from T(λ)

Magnetic frequency tuning of the microwave Gunn diode oscillator

It has been found experimentally that the oscillation frequency of a Gunn diode placed in the low-dimensional resonance system “metal pin–closely set short-circuiter” can be effectively controlled by magnetic field applied in the normal direction with respect to the waveguide wide wall