Fourth order exceptional points with spinning resonators

Investigation of exceptional points mostly focuses on the second order case and employs the gain-involved parity-time (PT) symmetric systems. Here, we propose an approach to implementing fourth order exceptional points (FOEPs) using directly coupled optical resonators with rotation. On resonance, the system manifests FOEP through tuning the spinning velocity to targeted values. Eigenfrequency bifurcation and enhanced sensitivity for nanoparticle have been presented. Also, near FOEP, nonreciprocal light propagation exhibits great boost and dramatic change, which may be applied to high-efficiency isolators and circulators.

Chiral light in single-handed Fabry-Perot resonators

Chirality is a universal phenomenon that is encountered on many different length scales in nature. Interaction of chiral matter with chiral light results in the effect of circular dichroism, which underlies many techniques of discriminating molecular enantiomers. Enhancing dichroic effects is typically achieved by interfacing chiral matter with various optical resonators. In this context it is important to understand how the eigenmodes of optical cavities relate to the field states with well-defined handedness. Here, we present the model of a single-handedness chiral optical cavity supporting only an eigenmode of a given handedness without the presence of modes of other helicity. Resonant excitation of the cavity with light of appropriate handedness enables formation of a helical standing wave with a uniform chirality density, while the opposite handedness does not cause any resonant effects. Our findings expand the set of tools for investigations of chiral matter and open the door towards studies of chiral electromagnetic vacuum states.

The CMB, Preferred Reference System, and Dragging of Light in the Earth Frame

The dominant CMB dipole anisotropy is a Doppler effect due to a particular motion of the solar system with a velocity of 370 km/s. Since this derives from peculiar motions and local inhomogeneities, one could meaningfully consider a fundamental frame of rest Σ associated with the Universe as a whole. From the group properties of Lorentz transformations, two observers, individually moving within Σ, would still be connected by the relativistic composition rules. However, the ultimate implications could be substantial. Physical interpretation is thus traditionally demanded in order to correlate some of the dragging of light observed in the laboratory with the direct CMB observations. Today, the small residuals—from those of Michelson–Morley to present experiments with optical resonators—are just considered instrumental artifacts. However, if the velocity of light in the interferometers is not the same parameter “c” of Lorentz transformations, nothing would prevent a non-zero dragging. Furthermore, the observable effects would be much smaller than what is classically expected and would most likely be of an irregular nature. We review an alternative reading of experiments that leads to remarkable correlations with the CMB observations. Notably, we explain the irregular 10−15 fractional frequency shift presently measured with optical resonators operating in vacuum and solid dielectrics. For integration times of about 1 s and a typical Central European latitude, we also predict daily variations of the Allan variance in the range (5÷12)·10−16.

Information-Measuring Complex to Detect High Frequency Gravitational Waves

The gravitational waves predicted by the general theory of relativity and detected by the Laser Interferometer Gravitational-wave Observatory (LIGO) have typical frequencies in the range of 30 ... 300 Hz. Current theories of gravity predict the existence of high-frequency gravitational waves with frequencies of 10 ... 100 MHz, including those of cosmological origin, induced by quantum fluctuations of the scalar field at the stage of cosmological inflation in the early Universe.Multi-beam optical resonators, in particular the Fabry-Perot interferometers, can be used to detect high-frequency gravitational waves. When using multi-beam optical resonators, it is possible to use the phenomenon of low-frequency optical resonance, which allows us to have a selective response to the gravitational wave effect. The gravitational-optical resonance in a multi-beam interferometer occurs if the condition is fulfilled that an integer number of half-waves of gravitational radiation is along the length of the resonator.The use of a multi-beam interferometer to detect high-frequency gravitational waves does not require the creation of a complex system for decoupling mirrors used for gravitational antennas operating in the low-frequency part of the spectrum. This is due to the fact that the frequency of mechanical vibrations of the interferometer mirrors is significantly less than the frequency of the gravitational wave.The paper considers possible optical schemes of a high-frequency gravitational antenna: based on the traditional Michelson interferometer, in the arms of which two Fabry-Perot interferometers are available, and on the basis of the Mach-Zehnder optical scheme, where Fabry-Perot interferometers can be made in the form of two perpendicular arms, with reflecting mirrors at the bend of the beam. The advantage of the second scheme is that three photo-detectors, one being main and two others being auxiliary, can be used, and there is a possibility to detect radiation transmitted by Fabry-Perot interferometers.To prove that detection of high-frequency gravitational waves is possible, a potential sensitivity of the high-frequency gravitational antenna has been estimated in the paper.