UnDiff: Unsupervised Voice Restoration with Unconditional Diffusion Model

This paper introduces UnDiff, a diffusion probabilistic model capable of solving various speech inverse tasks. Being once trained for speech waveform generation in an unconditional manner, it can be adapted to different tasks including degradation inversion, neural vocoding, and source separation. In this paper, we, first, tackle the challenging problem of unconditional waveform generation by comparing different neural architectures and preconditioning domains. After that, we demonstrate how the trained unconditional diffusion could be adapted to different tasks of speech processing by the means of recent developments in post-training conditioning of diffusion models. Finally, we demonstrate the performance of the proposed technique on the tasks of bandwidth extension, declipping, vocoding, and speech source separation and compare it to the baselines. The codes will be released soon.Comment: Accepted to Interspeech 202

Chiral Optical Tamm States at the Interface between a Cholesteric and an All-Dielectric Polarization-Preserving Anisotropic Mirror

The chiral optical Tamm state is a new localized state of light at the interface between a polarization-preserving anisotropic mirror and an optically chiral medium such as a cholesteric liquid crystal. In this study the metal-free polarization-preserving mirror is used for efficient resonance control. We stress the advantage of the all-dielectric structure in obtaining high Q factor. The light is localized near the interface and the field decreases exponentially with the distance from the interface. The penetration of the field into the chiral medium is virtually blocked at wavelengths corresponding to the photonic band gap and close to the pitch of the helix. The polarization-preserving mirror has another photonic band gap as well. Our analytics agrees well with precise calculations, enabling intelligent design for laser and sensing applications.Comment: in Russia

Hinton, Deane R.

The chiral optical Tamm state (COTS) is a special localized state at the interface of a handedness-preserving mirror and a structurally chiral medium such as a cholesteric liquid crystal or a chiral sculptured thin film. The spectral behavior of COTS, observed as reflection resonances, is described by the temporal coupled-mode theory. Mode coupling is different for two circular light polarizations because COTS has a helix structure replicating that of the cholesteric. The mode coupling for co-handed circularly polarized light exponentially attenuates with the cholesteric layer thickness since the COTS frequency falls into the stop band. Cross-handed circularly polarized light freely goes through the cholesteric layer and can excite COTS when reflected from the handedness-preserving mirror. The coupling in this case is proportional to anisotropy of the cholesteric and theoretically it is only anisotropy of magnetic permittivity that can ultimately cancel this coupling. These two couplings being equal results in a polarization crossover (the Kopp--Genack effect) for which a linear polarization is optimal to excite COTS. The corresponding cholesteric thickness and scattering matrix for COTS are generally described by simple expressions

Transparent conductive oxides for the epsilon-near-zero Tamm plasmon polaritons

We demonstrate the possibility of using transparent conducting oxides [aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), indium tin oxide (ITO)] to form Tamm plasmon polaritons in the near-infrared spectral range where the permittivity of oxides is near zero. The spectral properties of the structures are investigated in the framework of the temporal coupled-mode theory and confirmed by the transfer matrix method. It is found that in the critical coupling conditions, the maximal -factor of a Tamm plasmon polariton is achieved when a photonic crystal is conjugated with the AZO film, while at the conjugation with the ITO films, the broadest spectral line is obtained. The sensitivity of the wavelength and spectral width of the Tamm plasmon polariton to changes in the oxide film thickness, bulk concentration of a dopant, and angle of incidence is demonstrated

Localized modes in chiral photonic structures

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.We discuss chiral structures in self-organizing, artificial, and biological materials. A review of experimental studies and recent advances in the localization of light in chiral structures is given. The behavior of polarized resonant modes in such structures is examined using the example of a one-dimensional photonic crystal containing liquid crystal materials. The anomalous spectral shifts of transmission peaks are interpreted as the contribution of the geometric phase caused by the twisting of the layers of the liquid crystal. The optical Tamm state localized at the boundary between chiral and nonchiral mirrors in the form of a cholesteric layer and a polarization-preserving anisotropic mirror is analytically and numerically described. Considerable attention is paid to the presentation of the properties of localized optical modes in the cholesteric with a resonant metal-dielectric nanocomposite. New possibilities for controlling the properties of the photonic structure are noted, due to the combination of the dispersion of the resonant medium and the intrinsic dispersion of the cholesteric. Attention is focused on controlled hybrid modes in the cholesteric structure formed by the coupling of localized modes. Possible applications and further ways of developing the concept of chiral photonic structures are deliberated

Theoretical prerequisites for improving the body low loader granular fertilizer spreader

It is known that the use of granular forms of fertilizers is a universal solution for plant growing enterprises using organic, mineral, organomineral fertilizers in their activities. For crop farming enterprises, the application of granular fertilizers is the most convenient way to enrich the soil with nutrients. For the surface main application and top dressing, spreaders of different designs are used, distributing fertilizers in a continuous layer with different indicators of uniformity. At present, the development of machines of various designs is underway to operate applying solid fertilizers. The main tasks of research by various authors in the field of mechanization of the distribution of fertilizers over the surface of the field are to reduce the uneven distribution of fertilizers across the width, increase the sowing width, as well as reduce the changeover time for the fertilization operation. The article presents studies related to the improvement of the design of the working bodies of the machine for applying granular fertilizers, installed on the horizontal axis of rotation. To achieve the goal of increasing the working width of the unit without reducing the quality of the sifting, an option was proposed to supplement the design of a low-frame body spreader for solid fertilizers

Hybrid Tamm and surface plasmon polaritons in resonant photonic structure

Hybrid modes originating from the coupling of the Tamm and surface plasmon polaritons excited in a one-dimensional resonant photonic structure are demonstrated. The structure represents a photonic crystal bounded by a nanocomposite film consisting of a transparent matrix and silver nanoparticles uniformly distributed over its volume. In comparison with structures on planar metal films the volume concentration and shape of nanoparticles are of great help in configuring the hybrid mode properties, including their wavelength and splitting. Also the radiation incidence angle variation opens the possibility of fine-tuning the energy spectra of the structure. We demonstrate the high-sensitivity of optical sensors based on the resonant photonic structure