Frequency Of Mirror Research Articles

Enhancing the force sensitivity of a squeezed light optomechanical interferometer.

Application of frequency-dependent squeezed vacuum improves the force sensitivity of an optomechanical interferometer beyond the standard quantum limit by a factor of e-r, where r is the squeezing parameter. In this work, we show that the application of squeezed light along with quantum back-action nullifying meter in an optomechanical cavity with mechanical mirror in middle configuration can enhance the sensitivity beyond the standard quantum limit by a factor of e-reff, where reff = r + ln(4Δ/ζ)/2, for 0 < ζ/Δ < 1, with ζ as the optomechanical cavity decay rate and Δ as the detuning between cavity eigenfrequency and driving field. The technique described in this work is restricted to frequencies much smaller than the resonance frequency of the mechanical mirror. We further studied the sensitivity as a function of temperature, mechanical mirror reflectivity, and input laser power.

Casimir-force-assisted ground-state cooling and macroscopic quantum coherence

We theoretically investigate the ground-state cooling and macroscopic quantum coherence of the mechanical motion in a hybrid optomechanical system with a movable cavity wall and a nearby oscillation nanosphere. In the study, the vacuum effect is used to realize a direct coupling between the movable cavity wall and the oscillation nanosphere, which plays a role in the energy transfer channel between them. We find that when the Casimir force between the mechanical oscillators is included, the ground-state cooling and the macroscopic quantum coherence of the oscillation nanosphere can be realized in a certain range of effective detuning and driving power. We discuss in detail the dependence of the quantum properties on the amplitude of Casimir force, the driving power, the optical effective detuning and the oscillation frequency of the movable mirror. The results suggest that the quantum phenomenon of a single nanosphere can be manipulated by coupling an optomechanical cavity to the nanosphere and therefore has a potential application in quantum optics and the utilization of vacuum force.

Topology Optimization Based Parametric Design of Balloon Borne Telescope’s Primary Mirror

For balloon-borne telescopes, the primary mirror is the most important optical element, but designing a primary mirror with an excellent overall performance is a challenge. To comprehensively consider the contradictory objectives of the root mean square (RMS) surface error under gravity in the X and Z directions, the mass and fundamental frequency of the primary mirror, a parametric primary mirror design using the compromise programming method based on topology optimization is proposed. The parametric design of the compromise programming method based on topology optimization is used to find the optimal solution for X-direction RMS (RMSx), Z-direction RMS (RMSz), mass, and fundamental frequency. Compared with the initial primary mirror structure designed according to traditional experience, the overall performance is improved. Results show that the respective mass of the primary mirror, the RMSx and the RMSz decreased by 8.5%, 14.3% and 10.5% compared to those before optimization. Comprehensive consideration can prove the effectiveness of parametric design based on the topology optimization of the primary mirror. This method provides a reference for the design of other primary mirrors for balloon-borne telescope and space cameras.

3-D Printed All-Dielectric Dual-Band Broadband Reflectarray With a Large Frequency Ratio

This communication proposes a new all-dielectric broadband dual-band reflectarray with a large frequency ratio using low-cost 3-D printing. In contrast to conventional reflectarrays using metallic resonant cells or dielectric slabs as phasing elements with full metal ground, the proposed design uses air as the phasing element and a stepped dielectric mirror structure as the ground. In this way, the metal ground is removed, which makes the design an all-dielectric one. Taking advantage of the dielectric mirror that only exhibits a bandgap in the predesigned band while allowing electromagnetic (EM) waves to pass through it at the frequency out of the bandgap region, a dual-band reflectarray is obtained. By properly selecting the bandgap frequency of the dielectric mirror, the dual-band frequency ratio is scalable and can be very large. Furthermore, instead of using a metallic or dielectric resonator based on resonance, air layers with linear phase response are adopted as the phasing element. Thus, the reflectarray shows broadband and stable performance over the dual-band. Compared with the state-of-the-art works using printed circuit boards (PCBs) or microfabrication, the proposed design is low cost and lightweight, and can be rapidly prototyped. For proof-of-concept, a prototype operating at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> -band and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V$ </tex-math></inline-formula> -band with a frequency ratio of 2.7 is printed and measured.

Quantum optomechanics without the radiation pressure force noise.

This Letter proposes a new method to eliminate the quantum radiation pressure force noise in optomechanics at frequencies much smaller than the resonance frequency of the optomechanical mirror. With no radiation pressure force noise, the shot noise and thermal noise together determine the total noise in the system. The force sensitivity of the optomechanical cavity is improved beyond standard quantum limit at frequencies much smaller than the resonance frequency of the mechanical oscillator. Finally, optimum optomechanical cavity design parameters for attaining the best sensitivity are discussed.

Research on high performance support technology of space-based large aperture mirror

A three-point back support structure including cone sleeve, flexible structure and adjustable pad is designed for the space-based mirror support to meet the requirements of small surface shape error, high supporting reliability and stability, of which in-depth study on support principle and engineering realization is conducted in this paper. The error sources which influence the surface shape error of the mirror subassembly with three-point back support is summarized. The mechanism of surface shape variation caused by various error sources is studied. The support structure with high stiffness for alleviating the surface shape error caused by various error sources is designed, which can increase the fundamental frequency of mirror subassembly and protect it from yield failure under the condition of dynamic load. Firstly, the static and dynamic simulation of the three-point back support structure model is carried out by means of finite element analysis. Then the dynamic and partial static experiments are performed using aluminum mirror and actual supporting structure. The results show that the surface shape error of mirror with the three-point support structure is superior to λ/80(λ = 632.8 nm), the displacement of mirror is smaller than 0.015 mm, the inclination angle is smaller than 2″, the mass of the mirror subassembly is smaller than 310 kg. The mirror subassembly has a reasonable modal distribution, the fundamental frequency is 128 Hz, which is much higher than the requirement of 120 Hz. The maximum magnification of the mirror assembly excited by the sinusoidal vibration and the random vibration is 2.51and the maximum stress is 286 MPa under the same working condition, which is much lower than the yield limit of the selected material. A kind of segmented metering assembly method is formed and applied to make sure 2 m space-based large-aperture mirror has lower surface shape error according to the theoretical research results in this paper which the surface shape error of the space-based large-aperture mirror supported by three-point on the back which optical axis is in the horizontal direction in test, installation and adjustment is very sensitive to the deviation between rotating shaft of flexible structure and the neutral plane of the mirror in the direction of the optical axis.

Mode locking in an optomechanical cavity

We experimentally study a fiber-based optical ring cavity integrated with a mechanical resonator mirror and an optical amplifier. The device exhibits a variety of intriguing nonlinear effects including synchronization and self-excited oscillation. Passively generated optical pulses are observed when the frequency of the optical ring cavity is tuned very close to the mechanical frequency of the suspended mirror. The optical power at the threshold of this process of mechanical mode locking is found to be related to quantum noise of the optical amplifier.

Reflectivity degradation of the Subaru Telescope primary mirror

Abstract The reflectivity degradation of a telescope’s mirrors is broadly known; however, due to lack of suitable instrumentation, it has not been sufficiently studied. To overcome this situation, we developed a portable spectrophotometer named the “Subaru Portable Spectrophotometer” (SPS) to measure the absolute spectral reflectivity in-situ for a large optical component, such as a telescope’s primary mirror. The reflectivity of the Subaru telescope primary mirror was measured with SPS right before its eighth coating, and it showed larger degradation at shorter wavelength. Since then, the reflectivity degradation has been monitored with SPS. To explain the wavelength-dependence of the reflectivity degradation, we developed a two-factor model of a simple achromatic loss and scattering. The two-factor model shows an excellent match to real degradation. The time evolution of the achromatic loss and scattering are shown, and these are about 2.3% achromatic loss per year, and the color-dependent loss from root-mean-square (rms) surface roughness, which is the cause of scattering, increases from an initial small roughness after coating by about 40 Å per year. From these results, we extrapolated the model to a long-elapsed time to estimate the reflectivity in the future. The reflectivity of the Subaru Telescope primary mirror is expected to decrease about 22% at 400 nm by 1200 days after coating, and by 10% at 950 nm. We deduced the most efficient coating frequency of the Subaru Telescope primary mirror that maximizes the number of photons that can be acquired, and it is once every three years.

Multi time sequence flashing laser test for high frequency swing mirror

In order to solve the problem of low sampling rate and to meet the requirements of high frequency swing mirror measurement, based on the principle of equivalent sampling, a multi time series high accuracy non-contact swing mirror detection system is designed. First, with the laser pulse control circuit, multi time sequence flashing laser lighting is achieved and the spot position is obtained on the CCD target plane. Then, according to the image of the laser spot position, calculate the mirror swing angle and angular velocity by the time interval between adjacent spot positions. The experimental results show that the angle resolution of the detection system is 0.005°. The time resolution can reach the microsecond order, and the angular velocity measurement error is less than ±7%. The system improves the sampling frequency of swing mirror measuring and meets the requirements of high frequency swing mirror test.

Controlling the entanglement of mechanical oscillators in composite optomechanical system**Project supported by the National Natural Science Foundation of China (Grant Nos. 11704026 and 11461016), the Fund from Guizhou University of Finance and Economics, China (Grant No. 2017XZD01), and the Guizhou Youth Science and Technology Talent Development Project (Grant Nos. [2016] 170 and [2017] 150).

A controllable entanglement scheme of two mechanical oscillators is proposed in a composite optomechanical system. In the case of strong driving and high dissipation, the dynamics of the movable mirror of the optomechanical cavity is characterized by an effective frequency in the long-time evolution of the system. Considering the classical nonlinear effects in an optomechanical system, we investigate the relationship between the effective frequency of the movable mirror and the adjustable parameters of the cavity. It shows that the effective frequency of the movable mirror can be adjusted ranging from ωm (the resonance frequency of the coupling oscillator) to −ωm. Under the condition of experimental realization, we can generate and control steady-state entanglement between two oscillators by adjusting the effective frequency of the movable mirror and reducing the effective dissipation by selecting the parameter of the cavity driving laser appropriately. Our scheme provides a promising platform to control the steady-state behavior of solid-state qubits using classical manipulation, which is significant for quantum information processing and fundamental research.

Experimental Study of Metrological Characteristics of the Automated Interferometric System for Measuring the Surface Shape of Diffusely Reflecting Objects

The metrological characteristics of an automated interferometric system for measuring the surface shape of diffusely reflecting objects have been experimentally studied. Changes in the amplitude of the output signal during modulation of the optical path difference were studied and visualization of the effect of introduced interference on the measurement error was made. It is established that as the angle of incidence of optical radiation increases, the duration of the interference signal increases and, correspondingly, the measurement error of the automated interferometric system. The dependence of the measurement range on the scanning frequency of the reference mirror is obtained. The measurement error of an automated interferometric system under normal illumination does not exceed 0.67 μm.

Large-Aperture kHz Operating Frequency Ti-alloy Based Optical Micro Scanning Mirror for LiDAR Application

A micro scanning mirror is an optical device used to scan laser beams which can be used for Light Detection and Ranging (LiDAR) in applications like unmanned driving or Unmanned Aerial Vehicle (UAV). The MEMS scanning mirror’s light-weight and low-power make it a useful device in LiDAR applications. However, the MEMS scanning mirror’s small aperture limits its application because it is too small to deflect faint receiving light. In this paper, we present a Ti-alloy-based electromagnetic micro scanning mirror with very large-aperture (12 mm) and rapid scanning frequency (1.24 kHz). The size of micro-scanner’s mirror plate reached 12 mm, which is much larger than familiar MEMS scanning mirror. The scanner is designed using MEMS design method and fabricated by electro-sparking manufacture method. As the experimental results show, the resonant frequency of the micro scanning mirror is 1240 Hz and the optical scanning angle can reach 26 degrees at resonance frequency when the actuation current is 250 mApp.

Tunable double optomechanical induced transparency in an optomechanical system with Bose–Einstein condensate

We investigate the double optomechanically induced transparency (OMIT) of a weak problem field in a hybrid optomechanical system, composed of a Bose–Einstein condensate (BEC), a movable mirror and an optical cavity. Contrast to the single OMIT window in a traditional optomechanical system, the frequency difference between the BEC and the moving mirror in our system can lead to the splitting of the single OMIT window into two transparency windows. Interestingly, the splitting of the two windows varies near linearly with the frequency difference and is robust against the cavity decay. This property can be applied to detect the frequency of the movable mirror. Besides, the driving power and the BEC-cavity coupling strength play a key role in controlling the width of the two transparency windows.

Robust entanglement between a movable mirror and atomic ensemble and entanglement transfer in coupled optomechanical system.

We propose a scheme for the creation of robust entanglement between a movable mirror and atomic ensemble at the macroscopic level in coupled optomechanical system. We numerically simulate the degree of entanglement of the bipartite macroscopic entanglement and show that it depends on the coupling strength between the cavities and is robust with respect to the certain environment temperature. Inspiringly and surprisingly, according to the reported relation between the mechanical damping rate and the mechanical frequency of the movable mirror, the numerical simulation result shows that such bipartite macroscopic entanglement persists for environment temperature up to 170 K, which breaks the liquid nitrogen cooling and liquid helium cooling and largely lowers down the experiment cost. We also investigate the entanglement transfer based on this coupled system. The scheme can be used for the realization of quantum memories for continuous variable quantum information processing and quantum-limited displacement measurements.

Speckle reduction in laser picoprojector by combining optical phase matrix with twin green lasers and oscillating MEMS mirror for coherence suppression

The combined speckle reduction method is proposed and designed for laser picoprojectors taking small size, high optical power, and good image preservation into account. An optical phase matrix, twin green lasers, and an oscillating MEMS scanning mirror are used to suppress the speckle by reducing spatial and temporal coherences. The optical phase matrix is designed using a 5 µm pixel pitch based on Matlab simulation results and fabricated by imprinting. The twin green lasers with a modulation configuration and an oscillating MEMS scanning mirror are also applied taking the resolution of the display image and the scanning frequency of the MEMS scanning mirror into account. From the experimental results, it is confirmed that the speckle contrast is reduced by 47.47% by the optical phase matrix, 27.93% by the twin green lasers, and 18.89% by the oscillating MEMS scanning mirror. Finally, the combined speckle contrast results in a speckle reduction efficiency of 53.80% with a relatively small optical power loss of 18.21%.

Microfabricated water-immersible scanning mirror with a small form factor for handheld ultrasound and photoacoustic microscopy

Microscanning mirrors that can operate reliably under water are useful in both ultrasound and photoacoustic microscopic imaging, where fast scanning of focused high-frequency ultrasound beams is desired for pixel-by-pixel data acquisition. We report the development of a new microfabricated water-immersible scanning mirror with a small form factor. It consists of an optically and acoustically reflective mirror plate which is supported by two flexible polymer hinges and driven by an integrated electromagnetic microactuator. It can achieve 1-axis scanning of ±12.1 deg at a resonant frequency of 250 Hz in air and 210 Hz in water, respectively. By optimizing the design and enhancing the fabrication with high-precision optical three-dimensional printing, the overall size of the scanning mirror module is less than 7 mm×5 mm×7 mm. The small form factor, large scanning angle, and high-resonant frequency of the new water-immersible scanning mirror make it suitable for building compact handheld imaging probes for in vivo high-speed and wide-field ultrasound and photoacoustic microscopy.

Edgewise connectivity: an approach to improving segmented primary mirror performance

As future astrophysics missions require space telescopes with greater sensitivity and angular resolution, the corresponding increase in the primary mirror diameter presents numerous challenges. Since fairing restrictions limit the maximum diameter of monolithic and deployable segmented mirrors that can be launched, there is a need for on-orbit assembly methods that decouple the mirror diameter from the choice of launch vehicle. In addition, larger mirrors are more susceptible to vibrations and are typically so lightly damped that vibrations could persist for some time if uncontrolled. To address these challenges, we present a segmented mirror architecture in which the segments are connected edgewise by mechanisms analogous to damped springs. These mechanisms can be damped springs, flux-pinning mechanisms, virtual mechanisms, or any other device with the same basic behavior. Using a parametric finite-element model, we show that for low to intermediate stiffnesses, the stiffness and damping contributions from the mechanisms improve both the natural frequency and disturbance response of the segmented mirror. At higher stiffnesses, the mechanisms structurally connect the segments, leading to a segmented mirror that performs comparably to a monolith—or better, depending on the mechanism damping—with the modular design enabling on-orbit assembly and scalability.

A 32 × 32 optical phased array using polysilicon sub-wavelength high-contrast-grating mirrors.

We report on microelectromechanical systems (MEMS)-actuated 32 × 32 optical phased arrays (OPAs) with high fill-factors and microsecond response time. To reduce the mirror weight and temperature-dependent curvature, we use high-contrast-grating (HCG) mirrors comprising a single layer of sub-wavelength polysilicon gratings with 400 nm thickness, 1250 nm pitch, and 570 nm grating bar width. The mirror has a broad reflection band and a peak reflectivity of 99.9% at 1550 nm wavelength. With 20 × 20 μm2 pixels and 2 μm, the OPA has a total aperture of 702 × 702 μm2 and a fill factor of 85%. The OPA is electrostatically controlled by voltage and has a total field of view of ± 2°, an instantaneous field of view (beam width) of 0.14°, and a response time of 3.8 μs. The latter agrees well with the mechanical resonance frequency of the HCG mirror (0.42 MHz).

Electromagnetically induced transparency in cavity optomechanical system with -type atomic medium

We study an ensemble of identical -type atoms confined inside a cavity optomechanical system. We show that when the atoms have no absorption and dispersion the output field of the optomechanical system present a transparency phenomenon. The oscillation of the mirror does not affect the transparency of the atomic medium while the existence of the atomic medium results in two transparency windows of the output cavity field. We also show that the frequency of the oscillation mirror affects the analogy transparency of the output cavity field.

Vibration Modal Analysis and Structural Optimal Design of Car Rear-View Mirror Based on ANSYS

In order to improve the safety of the moving car,we have to make simulation and analysis of the dynamic characteristics of the car rear-view mirror. We should consider, in addition to the geometric dimensions, standards and demands, a reasonable choice of the mirror size and installing position, the dynamic characteristics of the car rear-view mirror in the design of the car rear-view mirror. In this paper, we use the finite element software ANSYS to simulate the vibration frequency and vibration modals of the car rear-view mirror under the condition of excitation sources. Based on this and the strength analysis results of the rear-view mirror, we make a optimal design of the rear-view mirror structure. We get five-order vibration modals in working condition and analysis the size of displacement and deformation, and dynamic characteristics. The results show that because of the low modal frequency, the car rear-view mirror is easily inspired by the engine, powertrain system and road to vibrate. Besides, the deformation and the strain distribution of the rear-view mirror are not uniform. So we should control the low rank flexibility modal frequency within a certain threshold frequency when designing its structure. On the condition of little changes of its overall volume, the maximum equivalent stress of the rear-view mirror decreased by 30.5% through optimizing design.