We explore the nonlinear mixing and amplification of magnetic polariton modes in ultrasmall waveguides. Ultrasmall waveguide geometries can produce large oscillating microwave fields—up to about 500 Oe. Using these large fields, we examine nonlinear ferromagnetic dynamics in ribbons of Permalloy and Fe. In particular if two microwave signals at different frequencies are sent into the waveguide, we can increase the transmission of one wave by adding energy to the other wave. We also demonstrate the creation of new frequencies and the development of a comb of equally spaced frequencies. These experimental results are explained with perturbation theory and micromagnetics calculations.

We demonstrate an on-wafer liquid crystal phase shifter which has a tunable 0–300°/cm phase shift at 110 GHz. The results show no dispersion over the entire frequency range indicating a tunable “true time delay” of up to 2.5 ps/cm at all frequencies. The inherent losses in the liquid crystal are small, less than 1 dB/cm over the range of 1–110 GHz. The full tunability is achieved using small voltages, close to 10 V. We anticipate that one could achieve a phase shift of 600°/cm at 220 GHz.

We explore a new geometry allowing effective excitation of the lowest antisymmetric standing spin wave mode in ferromagnetic metallic films with symmetrical boundary conditions. The approach is based on the use of a coplanar waveguide with the ferromagnetic film, Permalloy (Py), playing the role of the signal line. In addition, we study a signal line which is a sandwich of Py inside two nonmagnetic metallic films. We find that the thickness and conductivity of the metal films can significantly alter the amount of absorption, at ferromagnetic resonance, between the symmetric and antisymmetric spin wave modes. The experimental results are supported by numerical calculations indicating the origin of the strength of the absorption.

No abstract

Electrically tunable double‐spurline notch filters with a nematic liquid crystal (LC) material as a dielectric medium were modeled, manufactured, and characterized. The spurlines, which were embedded into an inverted microstrip, consisted of quarter‐wavelength resonant elements. A Finite Difference Time Domain solver was used to model the filters. Photolithography and thin film deposition were employed to create the filters, followed by standard LC cell assembly. The filters, with central notch frequencies at 50 and 85 GHz, were characterized on‐wafer with a vector network analyzer. The stopband frequencies were tunable by 3% when a 14 volt peak‐to‐peak AC bias was applied across the 38 μm thick LC layer (electric field of 0.19 V/μm). The minimum stopband insertion loss of both filters achieved lower than −50 dB, while the stopband return loss varied from −4 to −12 dB. The −3 dB passband widths of the stopband filters were 12.2 and 28.3 GHz for the 50 and 85 GHz filters, respectively, giving a Q‐factor of 3–4.