A broadband and compact TE-pass/TM-stop polarizer is presented based on hybrid plasmonic grating (HPG) on an x-cut Lithium-Niobate-on-isolator (LNOI) platform. By comprehensively analyzing the effects of metal width on mode effective index, mode similarity, and mode conversion, we demonstrate the structure with a narrower metal width. The simulation results indicate that the polarizer with a compact length of 9 μm achieves an extinction ratio over 20 dB within the wavelength range from 1470 nm to 1700 nm. The insertion loss is below 2.3 dB in C-band. Furthermore, the polarizer exhibits large fabrication tolerance to current fabrication technology.

Radar warning receiver (RWR) plays a significant role in detecting weapon radar. The instantaneous frequency measurement (IFM) section with fast measuring response, large measurement bandwidth, moderate accuracy, and sensitivity is important for an all-threat-covered RWR. In this IFM method, a phase modulator (PM) in combination with a differentiation structure is employed to get rid of the DC drifting and makes the power response is a strict monotonous function of the input frequency. Therefore, the unambiguous determination can be made in a very large range, which guarantees the fast measuring response. According to the theoretical analysis, a strict monotonous amplitude comparison function (ACF) with the covering range higher than 40 GHz can be achieved. Besides, no filter or dispersion elements (DE) such as optical fibers are required, which makes the structure be very concise to meet the potential for integration in any receiving systems. Due to the limit operation range of the PM, only the range from 0.1 GHz to 25 GHz is demonstrated. The measurement error can be lower than 3%. Especially, benefited by the balance photo-diode (BPD), the sensitivity is good without any noise cancellation processing. The error of lower than 10% will be promised when the RF power level is - 40 dBm.

This article put forwards a simple microwave photonics measurement method for microwave doppler frequency shift (DFS) and angle of arrival (AOA), which obtains the information conveniently and precisely by comparing the frequency and phase shift between two channels signals. The DFS direction can be judged more intuitively thanks to the introduction of the reference signal. The system uses two parallel dual parallel Mach-Zehnder modulators (DPMZMs) for carrier suppression single-sideband (CS-SSB) modulation. A proof-of-concept experiment was taken, showing that during ±100 kHz, the DFS measurement error is <±0.1 Hz over a 40 GHz frequency range as well as power sensitivity is down to −50 dBm. What is more, the measurement error of AOA is < ±1° from 0° to 90°. This simple system acquits excellent width band performance without the optical filter, providing a reliable and more conducive to human-computer interaction solution for future measurement and sensing applications.

We proposed a compact and efficient polarization rotator (PR) based on an asymmetric hybrid plasmonics waveguide (HPW) on the lithium-niobate-on-insulator (LNOI) platform. We focus on the design of rotation angle and balance between the two hybrid modes. The presented device exhibits a polarization extinction ratio as high as 59.58 dB and an insertion loss of 1.44 dB with the rotation length of only 13.7 μm. The fabrication tolerances and a suitable process are also discussed to meet the state-of-art technology.

This article reports a microwave photonic reconfigurable high precision simple instantaneous frequency measurement system. With the first assistance of stacking ensemble learning method, it can achieve high measurement accuracy over a wide bandwidth. For introducing electrical and optical delays, the range and accuracy of the instantaneous frequency measurement method can be flexibly adjusted to suit the needs of various scenarios. Sufficient and systematic experimental results show that from 11GHz to 17GHz, the average measurement error is 4.39MHz. This simple system acquits reconfigurability and on-chip integration possibilities without dispersion elements, which reveals great potential in the future integrated array radar, detection, and other fields.

In this article, a reconfigurable mixer based on only one dual-polarization quadrature phase shift -keying modulator (DP-QPSKM) is proposed and comprehensively demonstrated for a radio-over-fiber (RoF) system. By changing the detection unit and adjusting the dc voltages, the single-ended, double-balanced, image (IM)-free, mixing spurs suppressed, and dispersion-immune mixing can be implemented. Experimental results show that the ~60-dB IM rejection ratio and the spur suppression ratio are achieved. Moreover, the dispersion-induced power fading is successfully compensated by the dc voltage adjustment. The spurious-free dynamic range (SFDR) is about 100.56 dB· Hz2/3. Only one optical path is required without extra optical filters or phase-related devices, which makes the structure concise and stable. This structure would be more compact to meet the potential of integration if a dispersion medium with smaller size is available.