Presence Of Optical Losses Research Articles

Memory-assisted quantum accelerometer with multi-bandwidth

The accelerometer plays a crucial role in inertial navigation. The performance of conventional accelerometers such as lasers is usually limited by the sensing elements and shot noise limitation (SNL). Here, we propose an advanced development of an accelerometer based on atom–light quantum correlation, which is composed of a cold atomic ensemble, light beams, and an atomic vapor cell. The cold atomic ensemble, prepared in a magneto-optical trap and free-falling in a vacuum chamber, interacts with light beams to generate atom–light quantum correlation. The atomic vapor cell is used as both a memory element storing the correlated photons emitted from cold atoms and a bandwidth controller through the control of free evolution time. Instead of using a conventional sensing element, the proposed accelerometer employs interference between quantum-correlated atoms and light to measure acceleration. Sensitivity below SNL can be achieved due to atom–light quantum correlation, even in the presence of optical loss and atomic decoherence. Sensitivity can be achieved at the ng / Hz level, based on evaluation via practical experimental conditions. The present design has a number of significant advantages over conventional accelerometers such as SNL-broken sensitivity, broad bandwidth from a few hundred Hz to near MHz, and avoidance of the technical restrictions of conventional sensing elements.

Master-equation treatment of nonlinear optomechanical systems with optical loss

Open-system dynamics play a key role in the experimental and theoretical study of cavity optomechanical systems. In many cases, the quantum Langevin equations have enabled excellent models for optical decoherence, yet a master-equation approach to the fully nonlinear optomechanical Hamiltonian has thus far proven more elusive. To address this outstanding question and broaden the mathematical tool set available, we derive a solution to the Lindblad master equation that models optical decoherence for a system evolving with the nonlinear optomechanical Hamiltonian. The method combines a Lie-algebra solution to the unitary dynamics with a vectorization of the Lindblad equation, and we demonstrate its applicability by considering the preparation of optical cat states via the optomechanical nonlinearity in the presence of optical loss. Our results provide a direct way of analytically assessing the impact of optical decoherence on the optomechanical intracavity state.

Magnetoplasmonic structures with broken spatial symmetry for light control at normal incidence

As magnetized media by their nature have broken time reciprocity, the spatial symmetry of a material is also crucial and it imposes some restrictions on observed optical phenomena. Thus, for the normal incidence of light the spatial inversion symmetry makes transmitted and reflected light insensitive to the direction of the in-plane magnetization of the sample. To avoid this limitation, we propose here an approach based on a magnetoplasmonic structure with broken spatial symmetry. Combination of the specially designed spatial asymmetry with magnetism in the presence of optical losses provides a different effect, the transverse magnetophotonic transmittance effect, notable magnetooptical modulation of the optical transmittance at normal incidence enhanced by surface plasmon excitation. As the phenomenon is sensitive to asymmetry, it can serve as a powerful tool to study spin waves and currents in magnonic and optospintronic devices. The approach to marry the concepts of magnetoplasmonics and a lack of spatial symmetry is promising for the design of nanophotonics devices with outstanding properties.

Role of the absorption on the spin-orbit interactions of light with Si nano-particles

The conservation of the photon total angular momentum in the incident direction in an axially symmetric scattering process is a very well known fact. Nonetheless, the redistribution of this conserved magnitude into its spin and orbital components, an effect known as the spin-orbit interaction (SOI) of light, is still a matter of active research. Here, we discuss the effect of the absorption on the SOI in the scattering of a subwavelength silicon particle. Describing the scattering process of an electric and a magnetic dipole, we show via the asymmetry parameter that the SOI of light in the scattering of high refractive index nanoparticles endures in the presence of optical losses. This effect results in optical mirages whose maximum values surpass those of an electric dipolar scatterer.

Fundamental limit of detection of photonic biosensors with coherent phase read-out.

Photonic biosensors offer label-free detection of biomolecules for applications ranging from clinical diagnosis to food quality monitoring. Both sensors based on Mach-Zehnder interferometers and ring resonators are widely used, but are usually read-out using different schemes, making a direct comparison of their fundamental limit of detection challenging. A coherent detection scheme, adapted from optical communication systems, has been recently shown to achieve excellent detection limits, using a simple fixed-wavelength source. Here we present, for the first time, a theoretical model to determine the fundamental limit of detection of such a coherent read-out system, for both interferometric and resonant sensors. Based on this analysis, we provide guidelines for sensor optimization in the presence of optical losses and show that interferometric sensors are preferable over resonant structures when the sensor size is not limited by the available sample volume.

High-finesse Fabry\u2013Perot cavities with bidimensional Si3N4 photonic-crystal slabs

Light scattering by a two-dimensional photonic-crystal slab (PCS) can result in marked interference effects associated with Fano resonances. Such devices offer appealing alternatives to distributed Bragg reflectors and filters for various applications, such as optical wavelength and polarization filters, reflectors, semiconductor lasers, photodetectors, bio-sensors and non-linear optical components. Suspended PCS also have natural applications in the field of optomechanics, where the mechanical modes of a suspended slab interact via radiation pressure with the optical field of a high-finesse cavity. The reflectivity and transmission properties of a defect-free suspended PCS around normal incidence can be used to couple out-of-plane mechanical modes to an optical field by integrating it in a free-space cavity. Here we demonstrate the successful implementation of a PCS reflector on a high-tensile stress Si3N4 nanomembrane. We illustrate the physical process underlying the high reflectivity by measuring the photonic-crystal band diagram. Moreover, we introduce a clear theoretical description of the membrane scattering properties in the presence of optical losses. By embedding the PCS inside a high-finesse cavity, we fully characterize its optical properties. The spectrally, angular- and polarization-resolved measurements demonstrate the wide tunability of the membrane’s reflectivity, from nearly 0 to 99.9470±0.0025%, and show that material absorption is not the main source of optical loss. Moreover, the cavity storage time demonstrated in this work exceeds the mechanical period of low-order mechanical drum modes. This so-called resolved-sideband condition is a prerequisite to achieve quantum control of the mechanical resonator with light.

Wave propagation through photonic waveguide lattices in the presence of optical gain and loss.

We investigate the effects of gain and loss on the light propagation through a lattice of coupled optical waveguides. We demonstrate that superdiffusive transport becomes diffusive in the presence of optical loss after a critical propagation distance as in [Phys. Rev. Lett.113, 123903 (2014)PRLTAO0031-900710.1103/PhysRevLett.113.123903]. However, when optical gain is introduced in the lattice of coupled waveguides, the beam broadening slows down from a superdiffusive to a highly subdiffusive regime after another critical distance. The critical distance decreases with increase of loss or gain in the waveguide lattice. For equal gain and loss, the value of critical distance in the array of active waveguides is much smaller than that in the case of lattice of lossy waveguides. Furthermore, we find that the effective width in the case of lossy waveguides decreases with increase of loss at the same propagation distance. Our results confirm that the regime of beam broadening does not depend on whether the gain is introduced in the waveguides or in their surroundings.

Critical Kerr nonlinear optical cavity in the presence of internal loss and driving noise

We theoretically analyze the noise transformation of a high-power continuous-wave light field that is reflected off a critical Kerr nonlinear cavity (KNLC). Our investigations are based on a rigorous treatment in the time domain. Thereby, realistic conditions of a specific experimental environment including optical intracavity loss and strong classical driving noise can be modeled for any KNLC. We show that, even in the presence of optical loss and driving noise, considerable squeezing levels can be achieved. We find that the achievable squeezing levels are not limited by the driving noise but solely by the amount of optical loss. Amplitude-quadrature squeezing of the reflected mean field is obtained if the KNLC's operating point is chosen properly. Consistently, a KNLC can provide a passive purely optical reduction of laser-power noise as experimentally demonstrated in Khalaidovski et al. [Phys. Rev. A 80, 053801 (2009)]. We apply our model to this experiment and find good agreement with measured noise spectra.

Compensation of soliton broadening in nonlinear optical fibers with loss

A novel optical fiber is proposed that supports the lowest-order soliton despite the presence of optical loss. Groupvelocity dispersion of this fiber decreases with distance, in accord with soliton attenuation that is due to the inherent optical loss of the fiber.

Soliton analysis with the propagating beam method

We demonstrate that the propagating beam method can be employed to determine the behavior of optical fiber solitons in the presence of optical loss, third order dispersion and fifth order nonlinearity. Using the method, we analyze and extend analytical and numerical results of other authors, concentrating principally on calculations involving N = 3 solitons. Our results demonstrate that in fibers with large third order dispersion, only the lowest-order solitons should be excited in communication applications.