An overview of the most recent developments and improvements to the low-loss TriPleX Si 3 N 4 waveguide technology is presented in this paper. The TriPleX platform provides a suite of waveguide geometries (box, double stripe, symmetric single stripe, and asymmetric double stripe) that can be combined to design complex functional circuits, but more important are manufactured in a single monolithic process flow to create a compact photonic integrated circuit. All functionalities of the integrated circuit are constructed using standard basic building blocks, namely straight and bent waveguides, splitters/combiners and couplers, spot size converters, and phase tuning elements. The basic functionalities that have been realized are: ring resonators and Mach-Zehnder interferometer filters, tunable delay elements, and waveguide switches. Combination of these basic functionalities evolves into more complex functions such as higher order filters, beamforming networks,
We present an overview of several microwave photonic processing functionalities based on combinations of Mach-Zehnder and ring resonator filters using the high index contrast silicon nitride (TriPleX™) waveguide technology. All functionalities are built using the same basic building blocks, namely straight waveguides, phase tuning elements and directional couplers. We recall previously shown measurements on high spurious free dynamic range microwave photonic (MWP) link, ultra-wideband pulse generation, instantaneous frequency measurements, Hilbert transformers, microwave polarization networks and demonstrate new measurements and functionalities on a 16 channel optical beamforming network and modulation format transformer as well as an outlook on future microwave photonic platform integration, which will lead to a significantly reduced footprint and thereby enables the path to commercially viable MWP systems.
We demonstrate a hybrid integrated and widely tunable diode laser with an intrinsic linewidth as narrow as 40 Hz, achieved with a single roundtrip through a low-loss feedback circuit that extends the cavity length to 0.5 meter on a chip. Employing solely dielectrics for single-roundtrip, single-mode resolved feedback filtering enables linewidth narrowing with increasing laser power, without limitations through nonlinear loss. We achieve single-frequency oscillation with up to 23 mW fiber coupled output power, 70-nm wide spectral coverage in the 1.55 µm wavelength range with 3 mW output and obtain more than 60 dB side mode suppression. Such properties and options for further linewidth narrowing render the approach of high interest for direct integration in photonic circuits serving microwave photonics, coherent communications, sensing and metrology with highest resolution.
Photonic chip based time-bin entanglement has attracted significant attention because of its potential for quantum communication and computation. Useful time-bin entanglement systems must be able to generate, manipulate and analyze entangled photons on a photonic chip for stable, scalable and reconfigurable operation. Here we report the first time-bin entanglement photonic chip that integrates time-bin generation, wavelength demultiplexing and entanglement analysis. A two-photon interference fringe with an 88.4% visibility is measured (without subtracting any noise), indicating the high performance of the chip. Our approach, based on a silicon nitride photonic circuit, which combines the low-loss characteristic of silica and tight integration features of silicon, paves the way for scalable real-world quantum information processors.Entanglement is at the heart of photonic quantum technologies such as secure communication [1], super-resolution metrology [2], and powerful computation [3]. Photons are usually entangled in one of three degrees of freedom: polarization, optical path, or time bin. On-chip polarization entangled photon sources have been reported [4,5], but only the components for photon generation were on-chip due to the difficulty of integrating polarization analysis devices. Chip-scale optical path entangled photon generation and analysis [6], and teleportation [7] have seen rapid development, aiming for on-chip quantum computation. Time-bin entanglement is of particular interest because it (i) can be extended to higher dimensions for computation [8]; (ii) is insensitive to polarization fluctuation and polarization dispersion, and therefore very promising for long distance quantum key distribution (QKD) [1]; and (iii) is naturally compatible with integrated optics: photons can be generated in nonlinear waveguides, entangled and analyzed using on-chip unbalanced Mach-Zehnder interferometers (UMZIs) [9,10].For time-bin entanglement to be useful in the real world, the onchip integration of the entire entanglement system is essential. The high performance of the entanglement system not only relies on photon generation, but also hinges on the compactness, scalability and reconfigurability of the photonic circuit that generates the time bins, demultiplex the photons and analyze the entanglement. Refs [9] and [10] reported photon generation from compact silicon devices, but the wavelength demultiplexing was off chip, and entanglement analysis was based on silica waveguides, which have large bending radii due to their low index contrast. These features are incompatible with high density integration.In this paper we report, for the first time, a time-bin entanglement photonic chip that integrates time-bin generation, wavelength demultiplexing and entanglement analysis. Our demonstration was based on a high index contrast silicon nitride (Si3N4) circuit. The waveguide bending radii were reduced from millimeter (for silica) to micrometer scale while maintaining low losses, making high density integration possibl...
We report on the spectral properties of a diode laser with a tunable external cavity mirror, realized as an integrated optics waveguide circuit. Even though the external cavity is short compared to that of other narrow bandwidth external cavity lasers, the spectral bandwidth of this tunable laser is as small as 25 kHz (FWHM). The side-mode suppression ratio (SMSR) is 50 dB. The laser is able to access preset wavelengths in 200 μs and can be tuned over the full telecommunications C-band (1530–1565 nm).
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