With the advancements in technologies such as space optical communication, laser radar, and holographic projection, there has been an increasing demand for beam scanning devices that possess stronger seismic resistance, higher robustness, greater integration, and faster scanning speeds. Focal plane switch beam scanners based on silicon photonics integration technology offer the ability to achieve on-chip beam selection and off-chip scanning. These scanners provide advantages such as smaller size, faster scanning speeds, easier control of optical path selection, and a fully solid-state design without mechanical structures. In terms of scanning dimensions, they can be categorized into one-dimensional (θ) and two-dimensional (θ, φ) scans. Expanding the dimensionality is crucial in order to fulfill the system's functions more effectively. However, most on-chip two-dimensional beam scanners currently available impose higher demands on the light source and power consumption due to their reliance on wavelength tuning of the laser source for angle changes in the second dimension. Furthermore, the minimum control number for N switches is log2N. In this paper, we present a novel two-dimensional beam scanner structure that enables the two-dimensional beam scanning without wavelength tuning of the laser source. Moreover, the maximum control number for N switches in our proposed structure is only 2 for optical path control. The configuration of this structure employs a cross-bar design to achieve these goals. We experimentally verified the performance of a 4x6 array structure, which exhibits a far-field beam divergence angle of 0.06°, a field of view ranging from 4.12°x1.69°, and a background noise suppression of 12.29dB. This on-chip two-dimensional beam scanner offers a simpler structure, lower control complexity, lesser power consumption, and wider application prospects.
Integrated silicon micro-ring resonator (MRR) has been widely used as on-chip single photon source. In this paper, we introduce an approach to generate frequency-degenerate photons by bidirectionally pumping an add-drop micro-ring resonator (MRR) within a Sagnac loop configuration. This scheme facilitates the concurrent generation of photon pairs from both clockwise (CW) and counterclockwise (CCW) directions, transforming a single MRR into a dual-source system. Through CMOS fabrication techniques, we realized the proposed device and conducted measurements of key parameters including the single side count rate (SSCR), coincidence count rate (CCR), and coincidence-to-accidental coincidence ratio (CAR) for both directional outputs. Notably, the CCRs exhibit remarkable similarity between the two sources, reaching approximately 550 Hz at an waveguide power of 0.59 mW. Furthermore, we observed a differential CAR, with the CCW direction yielding a lower value compared to the CW direction, with estimated maxima of 161 and 387, respectively. These findings underscore the viability of utilizing a singular MRR as a dual-source entity. Additionally, we outline the design of an on-chip structure for heralded Hong-Ou-Mandel (HOM) interference, necessitating 4-fold coincidences.Our work holds the promise of advancing the realm of large-scale integrated quantum photonic chips.
We propose and demonstrate a sub-gigahertz bandwidth photonic differentiator employing the self-induced optical modulation effect in a silicon-on-insulator micro-ring resonator. The all-passive DIFF is controlled through an all-optical pump-probe scheme. Input Gaussian-like pulses with 7.5ns pulse width are differentiated at high processing accuracy. A semi-analytical model that agrees with the experimental results is also derived. The DIFF’s energy efficiency is higher than 45%, far surpassing all previously reported schemes for sub-gigahertz bandwidth pulses. Our scheme expands the application potential of photonic DIFFs.
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