Centre for Ultrahigh Bandwidth Devices for Optical Systems

Insufficient receiver bandwidth destroys the orthogonality of Nyquist-shaped pulses, generating inter-symbol interference (ISI). We propose using an optical pre-sampler to alleviate the requirement on the receiver bandwidth through pulse re-shaping. Experiments and simulations using an optically shaped 40-Gbaud Nyquist-shaped on-off-keying signal (N-OOK) show receiver sensitivity improvements of 4- and 7.1-dB under 18- and 11-GHz receiver electrical bandwidths, respectively.

Modal analysis based on the quasi-normal modes (QNM), also called resonant\nstates, has emerged as a promising way for modeling the resonant interaction of\nlight with open optical cavities. However, the fields associated with QNM in\nopen photonic cavities diverge far away from the scatterer and the possibility\nof expanding the scattered field with resonant contributions only has not been\nestablished. Here, we address these two issues while restricting our study to\nthe case of a dispersionless spherical scatterer. First, we derive the rigorous\npole expansion of the $T$-matrix coefficients that link the scattered to the\nincident fields associated with an optical resonator. This expansion evinces\nthe existence of a non-resonant term. Second, in the time domain, the causality\nprinciple allows us to solve the problem of divergence and to derive a modal\nexpansion of the scattered field that does not diverge far from the scatterer.\n

Time-bin entangled photons allow robust entanglement distribution over quantum networks. Integrated photonic circuits positioned at the nodes of a quantum network can perform the important functions of generating highly entangled photons and precisely manipulating their quantum state. In this Letter, we demonstrate time-bin entangled photon generation, noise suppression, wavelength division, and entanglement analysis on a single photonic chip utilizing low-loss double-stripe silicon nitride waveguide structures. Quantum state tomography results show 91±0.7% fidelity compared with the ideal state, indicating that highly entangled photons are generated and analyzed. This work represents a crucial step toward practical quantum networks.

We present a 10-GHz granularity reconfigurable WDM superchannel filter in a photonic integrated circuit. The filter uses a ring-resonator-assisted tapped-delay-line topology. An example configuration with two ring resonators and four tapped delay lines provides a spectral filter with a flat-top passband, a roll-off factor of 8%, a tunable central wavelength, and a selectable free spectral range, i.e., 2× or 4× the 3-dB passband bandwidth. The device was fabricated in a silicon nitride (Si3N4/SiO2) waveguide with a chip area of 0.36 cm2 and has a fiber-to-fiber insertion loss of 5 dB. We experimentally demonstrate the filter for selecting a subchannel from a WDM superchannel comprising 10-GHz subchannels with 10% and zero guard bands. Owing to the infinite impulse responses of ring resonators, this filter requires a significantly smaller area and fewer tuning elements compared with designs based on only tapped-delay-line finite-impulse-response filters. This paper contributes to the creation of chip-scale all-optical WDM superchannel transceivers and reconfigurable optical add/drop multiplexers (ROADMs).

Biological systems have been using nanometre‐scale architectures to produce striking optical effects and the way these natural photonic structures manipulate the flow of light has inspired many technological applications. Nevertheless, the applications of these natural structures in photonic devices require appropriate fabrication techniques able to tailor and enhance the natural features of the biological systems. In this communication the authors report on the development of a layered‐composite nanometric Sb2Te3 material for the realization of bio‐inspired three‐dimensional chiral photonic crystals exceeding their natural optical properties. The authors demonstrate that the deposition of Sb2Te3 on laser written polymer templates can fabricate biomimetic photonic structures with superior control over size, periodicity, filling fraction, and refractive index, compared with the natural counterparts. In this way the refractive index of the photonic crystals can be increased by 100% and the photonic bandgap for use in practical devices can be precisely engineered. These bio‐inspired structures can be useful in the investigation of new branches of photonics and in the development of novel chiral optical devices capable of manipulating photons in three dimensions.

We show that a simplified, single-photodiode per polarization heterodyne receiver is able to directly suppress signal-signal beat interference (SSBI), without the need for cancellation in the digital domain. We characterize performance degradation due to SSBI, and show that a strong LO in the receiver can mitigate SSBI. Transmission of 400 Gb/s-class signals is shown over single fiber spans of up to 160 km, and over field-deployed metropolitan area fiber. These results indicate that a single photodiode can be used to receive complex optical signals in high speed fiber systems without the need for SSBI cancellation in the digital domain.

Extreme sub-diffraction focusing of THz radiation is obtained by cascading two metamaterial wire array fiber hyperlenses. A record 1/176 of the wavelength is achieved, allowing squeezing 8.8 mm wavelength to a 50 micron spot.

We experimentally demonstrate that the coherence of Brillouin-based storage is not affected by simultaneous storage on another frequency channel because of the accumulated phase mismatch over the length of the spatially extended acoustic phonon.

We report mid-IR supercontinuum generation, from 2.9 to 7.7μm, in a CMOS compatible silicon-germanium waveguide. This 1.3 octave bright supercontinuum has been achieved in a low loss dispersion engineered air-clad Si0.6Ge0.4/Si waveguide.

Hot spots with significantly enhanced electric field are generally found in plasmonic systems composed of metallic nanoparticles/nanostructures. The combination of efficient photoluminescence and polarization and wavelength sensitivity offers the opportunity to encode such hot spots for optical memory, which is a promising way of storing big data. In article number 1701918, Sheng Lan, Shaolong Tie, Min Gu, and co-workers numerically analyze the impact of hot spots on the nonlinear optical response of metallic nanoparticles/nanostructures and demonstrate multidimensional optical data storage with ultrahigh density and ultralow energy.