arXiv subjects

Shuhang Zheng

Publications and source records attributed to Shuhang Zheng.

3 recordsLinked to original sources

arXiv2026

An integrated photonic millimeter-wave receiver with sub-ambient noise

Decades of progress in radiofrequency (RF) transistors and receiver frontends have profoundly impacted wireless communications, remote sensing, navigation, and instrumentation. Growing demands for data throughput in 6G networks, timing precision in positioning systems, and resolution in atmospheric sensing and automotive radar have pushed receiver frontends into the millimeter-wave (mmW) and sub-mmW/THz regimes. At these frequencies, however, the noise performance of field-effect transistors (FETs) degrades rapidly due to parasitic effects, limited carrier mobility, hot electrons, and shot noise. Parametric transducers that couple electromagnetic signals to optical fields offer quantum-limited sensitivity at room temperature. Electro-optic materials enable receivers that convert RF signals into optical phase shifts. While early demonstrations used resonant devices and recent efforts have focused on cryogenic microwave-to-optical quantum transduction, room-temperature electro-optic receivers have yet to achieve noise figures comparable to their electronic counterparts. Here we demonstrate a room-temperature integrated cavity electro-optic mmW receiver on a lithium tantalate (LiTaO3) photonic integrated circuit with 2.5% on-chip photon-number transduction efficiency, achieving 250 K noise temperature at 59.33 GHz--matching state-of-the-art LNAs. We report the first direct resolution of thermal noise in cavity electro-optic transduction, showing the system is fundamentally limited by thermal photon occupation (~100) in the mmW cavity. Our work establishes integrated photonics as a path to surpass electronic LNAs while offering exceptional resilience to strong electromagnetic inputs and immunity to EMI, establishing cavity electro-optics as a low-noise, chip-scale, EMI-resilient receiver frontend for mmW applications and scalable analog processing in the optical domain.

physics.optics↗

arXiv2023

BEVPlace: Learning LiDAR-based Place Recognition using Bird's Eye View Images

Place recognition is a key module for long-term SLAM systems. Current LiDAR-based place recognition methods usually use representations of point clouds such as unordered points or range images. These methods achieve high recall rates of retrieval, but their performance may degrade in the case of view variation or scene changes. In this work, we explore the potential of a different representation in place recognition, i.e. bird's eye view (BEV) images. We observe that the structural contents of BEV images are less influenced by rotations and translations of point clouds. We validate that, without any delicate design, a simple VGGNet trained on BEV images achieves comparable performance with the state-of-the-art place recognition methods in scenes of slight viewpoint changes. For more robust place recognition, we design a rotation-invariant network called BEVPlace. We use group convolution to extract rotation-equivariant local features from the images and NetVLAD for global feature aggregation. In addition, we observe that the distance between BEV features is correlated with the geometry distance of point clouds. Based on the observation, we develop a method to estimate the position of the query cloud, extending the usage of place recognition. The experiments conducted on large-scale public datasets show that our method 1) achieves state-of-the-art performance in terms of recall rates, 2) is robust to view changes, 3) shows strong generalization ability, and 4) can estimate the positions of query point clouds. Source codes are publicly available at https://github.com/zjuluolun/BEVPlace.

cs.CV↗

arXiv2023

I2P-Rec: Recognizing Images on Large-scale Point Cloud Maps through Bird's Eye View Projections

Place recognition is an important technique for autonomous cars to achieve full autonomy since it can provide an initial guess to online localization algorithms. Although current methods based on images or point clouds have achieved satisfactory performance, localizing the images on a large-scale point cloud map remains a fairly unexplored problem. This cross-modal matching task is challenging due to the difficulty in extracting consistent descriptors from images and point clouds. In this paper, we propose the I2P-Rec method to solve the problem by transforming the cross-modal data into the same modality. Specifically, we leverage on the recent success of depth estimation networks to recover point clouds from images. We then project the point clouds into Bird's Eye View (BEV) images. Using the BEV image as an intermediate representation, we extract global features with a Convolutional Neural Network followed by a NetVLAD layer to perform matching. The experimental results evaluated on the KITTI dataset show that, with only a small set of training data, I2P-Rec achieves recall rates at Top-1\% over 80\% and 90\%, when localizing monocular and stereo images on point cloud maps, respectively. We further evaluate I2P-Rec on a 1 km trajectory dataset collected by an autonomous logistics car and show that I2P-Rec can generalize well to previously unseen environments.

cs.CV↗