Changhong Chen

Dual-atom-interferometer configurations are widely used in gyroscopes and gradiometers to suppress common-mode noise and extract inertial signals with high precision. However, phase coupling between the two interferometers arising from shared Raman laser fields poses a significant challenge to simultaneous fringe locking. Here, we demonstrate a dual-atom-interferometric gyroscope–accelerometer that simultaneously locks both interference fringes at their respective mid-fringe operating points using independent direct digital synthesizer (DDS) channels to control the Raman phase shifts of the two interferometers. The proposed dual-fringe-locking scheme independently stabilizes both interferometers while preserving the common-mode noise rejection inherent to the dual-interferometer configuration. Compared with conventional full-fringe scanning, the scheme enables simultaneous rotation-rate and acceleration measurements with a higher data rate and improved sensitivity in both channels. These results demonstrate the potential of dual-fringe locking for high-precision quantum inertial sensing.

The errors of an inertial navigation system accumulate over time due to its operating principles and sensor limitations. Numerous studies have investigated hybrid inertial navigation schemes combining a cold atom interferometric gyroscope (CAIG) and a conventional inertial measurement unit. This paper constructs a dual-bias joint state model to realize decoupling of gyroscope biases between the conventional gyroscope and the CAIG, eliminating modeling error introduced by the drift-free reference sensor assumption. Furthermore, an adaptive Kalman filtering algorithm based on real-time residual autocorrelation identification is proposed to cope with the temporally correlated time-varying noise characteristics. A series of simulations including noise-characteristic verification and bias-decoupling comparison, as well as static physical experiments, are carried out to validate the bias-decoupling capability and overall navigation performance. Taking advantage of the low bias-drift property of the CAIG and the high sampling rate of conventional gyroscopes, static experimental results show that the hybrid navigation system with a single-axis CAIG reduces positioning errors by more than 85% after compensating for inertial sensor biases, and achieves a positioning accuracy of 5 nautical miles over a one-hour test. Although the current validation is limited to stationary conditions, this work provides a feasible solution for CAIG-aided hybrid inertial navigation.

Here, we demonstrate a longwave infrared pyroelectric detector of X-cut thin-film LiNbO3 on insulator, of which the performance is enhanced by a geometry-engineered coplanar electrode antenna, to harvest the infrared radiation from strong near-field confinement, and conductive domain-walls (DWs) from initial surface ferroelectric polar reversal to provide a pathway for efficiently collecting the pyroelectric charges. The film-constructed device in the surface DW structure behaves like a bulk one with the responsivity inversely proportional to the heat capacity instead, and scaling down the ferroelectric thickness allows the responsivity and speed to be engineered independently. This work paves the way for an on-chip system of ferroelectric DW detectors monolithic with the CMOS readout circuit, which is to be fabricated using the wafer's handle layer.

Compared with external coherent light manipulation, the realization of unilateral‐oriented thermal emission is more challenging. Although a specific metasurface is confirmed of the angular selectivity, the emissivity is generally mirror‐symmetric along the surface normal for uncorrelated phases between different positions of the thermal source. Here, from the metallic patch array conditions derived for unilateral thermal emission, a phase‐gradient metasurface in combination with surface plasmon polaritons is demonstrated which exhibit wide‐angled unilateral enhancements of thermal emission while the radiations in the symmetric directions are suppressed. By directly heating the device to 120 °C, the acquired spatial thermal emission spectrums indicate that at a wavelength of λ = 11.5 µm, the changed emissivity 0.61–0.46 with the orientation angle from 10° to 40° is asymmetric to 0.32–0.21 from −10° to −40°. Dealing with the phase response of meta‐atoms, the proposed method and phase‐modulated structure are helpful for the direction of controllable thermal emission.

Optical resonators with high Q-factor are of interest in infrared thermal sensors for their high-temperature sensitivity. Thin-film lithium niobate (LN), with low propagation loss in near-infrared, is a competitive material for a comparative advantage in thermal-optic coefficient and wider absorption range from longwave infrared (LWIR) to terahertz frequencies if compared with Si₃N₄ and SiO₂. Here, we present an LWIR sensor on the LN-photonic platform, where a high-Q microring resonator is monolithically integrated with a broadband LWIR radiation absorber, compatible with the multilayer-stacked LN photonic circuits. It is demonstrated that the radiation can induce a significant mode-frequency shift of near-infrared probe light on the thermal-optic effect, even if the device suffers from relatively high frequency noise. The noise equivalent temperature difference of the sensor is evaluated as 1.33 mK through a short-term frequency instability measurement. Under the radiation at a wavelength of λ = 9.1 µm, the device achieves a responsivity of 155.25 kHz/nW and a response time of 128 µs. The integrated device scheme on the LN-photonic platform holds great promise in developing a high-sensitivity infrared sensor, even to enable infrared imaging with a high signal-to-noise ratio.

Photonic Floquet–Bloch oscillations (FBOs), a new type of Bloch-like oscillations in photonic Floquet lattices, have recently been observed as a typical discrete self-imaging effect. Here, we theoretically investigate the spectral range of approximate photonic Floquet–Bloch oscillations in arrays of evanescently coupled optical waveguides and show the adjustability of the spectral range. At an appropriate amplitude of the Floquet modulation, we have demonstrated approximate photonic FBOs over a broad spectral range, termed “polychromatic photonic Floquet–Bloch oscillations,” which manifest as approximate self-imaging of polychromatic beams. Furthermore, by designing the functional form of the Floquet modulation, we can cascade two polychromatic photonic FBOs and further enhance the performance of polychromatic self-imaging. Our results provide a simple and novel mechanism for achieving polychromatic self-imaging in waveguide arrays and may find applications in polychromatic beam shaping and broadband optical signal processing.

Within Reststrahlen bands of polar semiconductors, surface phonon–plasmon coupling is of great interest in infrared nanophotonics. Here, we demonstrate an active long-wavelength infrared device of graphene integrated with an AlN/SiC polar heterostructure. As a low-loss dielectric design, the subwavelength structure device takes advantage of interfacial photogating effect on electrostatic doping of the graphene and the interfaced SiC, and the tunable spectral behavior is originated from the hybridization of the doping-dependent surface phonon–plasmon resonances. This finding provides a steady-state manipulating method to the surface modes for the low-loss nanophotonic devices on SiC platform, and the graphene Fermi level tunable to cross the Dirac point in a steady response even makes the intrinsic graphene photodetectors feasible.

Here we present a graphene-based long-wavelength infrared modulator characteristic of extra-high contrast, where the frequency detuning degree of magnetic and electric surface plasmons (SPs) is controllable by the gated graphene Fermi energy. If the device is designed to work in a strong SP-coupling regime by selecting an appropriate low-lossy gate dielectric thickness, a modulation depth (MD) up to ∼100% but insertion loss (IL) as low as ∼−0.37 dB is achievable. Moreover, a compromised MD > 90% with IL < −1.0 dB is still retainable in two broadband ranges. The disclosed underlying mechanism to the device working state in the strong, electromagnetic-induced transparency (EIT), or weak SP-coupling regime, indicates the coupling regime shows a strong dependence on the dielectric thickness, which is related to the magnetic-SP mode volume, while the working wavelength can be selected in a broader spectral range by scaling the device geometry. These findings are helpful to construct those optoelectronics for infrared absorption enhancement, EIT, and strong coupling spectral characteristic itself.

As the hole mobility increases with free carrier absorption (FCA), heavily doped p-type silicon has emerged as a promising candidate for detecting near-infrared (NIR) light with photonic energy below the semiconductor bandgap, and the hot-carrier photodetector is capable of high responsivity approaching commercially available devices. To enhance performance-related FCA of the semiconductor, here we demonstrate an all-silicon metasurface absorber designed in nanohole arrays and present an in-depth analysis on the electromagnetic resonance mechanism in the NIR spectral of interest. Multipole decomposition under a Cartesian coordinate system reveals that combining with the dielectric loss introduced by the doping, magnetic dipole resonances contribute predominantly to the absorption enhancement. This simple and easy-fabricated architecture has great potential for silicon hot-carrier photodetectors.