Silicon-based integrated spiral waveguides are extensively used as on-chip single-photon sources. However, inherent uncertainties and limitations in single-photon fidelity pose significant theoretical performance bottlenecks. These challenges often necessitate the multiplexing of multiple sources. In this paper, we propose a novel scheme for spatial multiplexing using bidirectional spirals. By pumping a spiral waveguide bidirectionally, photon pairs are generated in both clockwise (cw) and counterclockwise (ccw) directions, each producing signal-idler photon pairs in a two-mode squeezed state. Consequently, a single spiral waveguide can function as two spatially multiplexed sources. Using CMOS fabrication technology, we constructed a bidirectional spiral waveguide structure. We measured the coincidence count rates, heralded second-order correlation function, and coincidence to accidental ratio (CAR) as functions of pump power, both before and after multiplexing. Our experimental results demonstrated a 1.67-fold increase in performance post-multiplexing. This finding underscores the potential of bidirectional spirals as spatially multiplexed sources, paving the way for the largescale integration of future photonic quantum chips.
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.
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.
With the continuous development of silicon-based optoelectronic chips, their high-power applications in communication, ranging, and other fields are gradually increasing. However, the nonlinear effects of silicon (Si) cause significant output power loss when the input optical power surpasses a certain threshold. This nonlinear relationship between the input optical power and the chip's output power reduces its working performance. Therefore, the importance of regulating the nonlinear phenomena of the chip gradually becomes prominent. In this regard, Sb2Se3 is an excellent material. We propose a scheme to improve the nonlinear power threshold by depositing crystalline Sb2Se3 (c-Sb2Se3) on the top of Si waveguides. Noted that optical loss caused by nonlinear absorption can be depressed by the c-Sb2Se3 film, as well as loss compensation is proportional to the length of the c-Sb2Se3 film deposited. This article theoretically analyzes the characteristics of Sb2Se3, which material can compensate for the nonlinear effect of Si during high-power operation of Si chips. This compensation increases the optical power threshold of nonlinear excitation and is nonvolatile. C-Sb2Se3 films with different lengths (from 15 μm to 60 μm) were deposited on Si waveguides and Si microring resonators with different coupling gap (from 0.2 μm to 0.35 μm) respectively. The results demonstrate a significant improvement in the device's optical nonlinear power threshold. Furthermore, as the length of the c-Sb2Se3 film increases, the optical nonlinear power threshold increases more significantly.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.