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The article titled "Integrated Ultra-Wideband Dynamic Microwave Frequency Identification System in Lithium Niobate on Insulator" discusses the experimental demonstration of a microwave frequency identification system in lithium niobate on insulator (LNOI). The researchers were able to extend the bandwidth of microwave frequency systems to the millimeter-wave U-band by utilizing the electro-optical properties of lithium niobate. This development opens up possibilities for creating high-performance integrated microwave photonic devices on the LNOI platform. The authors of the article include LiHeng Wang, Zhen Han, Yong Zheng, Pu Zhang, YongHeng Jiang, HuiFu Xiao, BinJie Wang, Mei Xian Low, Aditya Dubey, Thach Giang Nguyen, Andreas Boes, Guanghui Ren, Ming Li, Arnan Mitchell, and Yonghui Tian. [Extracted from the article]

The article in Laser & Photonics Reviews discusses the use of photonic metamaterials on a lithium niobate platform to create high-performance polarization manipulating devices. Researchers, including Guanghui Ren and Yonghui Tian, have successfully developed devices such as polarization splitter rotators and polarizers by controlling the coupling state of different polarizations and reducing radiation loss at interfaces. This research showcases the potential for innovative applications of metamaterials in photonics technology. [Extracted from the article]

We demonstrate a photonic RF integrator based on an integrated soliton crystal micro-comb source. By multicasting and progressively delaying the input RF signal using a transversal structure, the input RF signal is integrated discretely. Up to 81 wavelengths are provided by the microcomb source, which enable a large time-bandwidth product of 81. Our approach also features a high degree of reconfigurability. By simply adjusting the value of dispersion (i.e., the length of dispersive fibre), the integration time window and resolution can be reconfigured to accommodate a diverse range of applications. We employed 13 km of standard single-mode fibre to achieve a large integration time window of ~6.8 ns, a time resolution as fast as ~84 ps, with a broad bandwidth of 11.9 GHz. In addition, we perform signal integration of a diverse range of input RF signals including Gaussian pulses with varying time widths, dual pulses with varying time intervals and a square waveform. The experimental results show good agreement with theory. These results verify our microcomb-based integrator as a competitive approach for RF signal integration with high performance and potentially lower cost and footprint. [ABSTRACT FROM AUTHOR]

We report a photonic-based radio frequency (RF) arbitrary waveform generator (AWG) using a soliton crystal micro-comb source with a free spectral range (FSR) of 48.9 GHz. The comb source provides over 80 wavelengths, or channels, that we use to successfully achieve arbitrary waveform shapes including square waveforms with a tunable duty ratio ranging from 10% to 90%, sawtooth waveforms with a tunable slope ratio of 0.2 to 1, and a symmetric concave quadratic chirp waveform with an instantaneous frequency of sub GHz. We achieve good agreement between theory and experiment, validating the effectiveness of this approach towards realizing high-performance, broad bandwidth, nearly user-defined RF waveform generation. [ABSTRACT FROM AUTHOR]

We report a photonic radio frequency (RF) fractional differentiator based on an integrated Kerr micro-comb source. The micro-comb source has a free spectral range (FSR) of 49 GHz, generating a large number of comb lines that serve as a high-performance multi-wavelength source for the differentiator. By programming and shaping the comb lines according to calculated tap weights, arbitrary fractional orders ranging from 0.15 to 0.90 are achieved over a broad RF operation bandwidth of 15.49 GHz. We experimentally characterize the frequency-domain RF amplitude and phase response as well as the temporal response with a Gaussian pulse input. The experimental results show good agreement with theory, confirming the effectiveness of our approach towards high-performance fractional differentiators featuring broad processing bandwidth, high reconfigurability, and potentially reduced sized and cost. [ABSTRACT FROM AUTHOR]

We report a broadband radio frequency (RF) channelizer with up to 92 channels using a coherent microcomb source. A soliton crystal microcomb, generated by a 49 GHz micro-ring resonator (MRR), is used as a multi-wavelength source. Due to its ultra-low comb spacing, up to 92 wavelengths are available in the C band, yielding a broad operation bandwidth. Another high-Q MRR is employed as a passive optical periodic filter to slice the RF spectrum with a high resolution of 121.4 MHz. We experimentally achieve an instantaneous RF operation bandwidth of 8.08 GHz and verify RF channelization up to 17.55 GHz via thermal tuning. Our approach is a significant step towards the monolithically integrated photonic RF receivers with reduced complexity, size, and unprecedented performance, which is important for wide RF applications ranging from broadband analog signal processing to digital-compatible signal detection. [ABSTRACT FROM AUTHOR]

We demonstrate photonic RF phase encoding based on an integrated micro-comb source. By assembling single-cycle Gaussian pulse replicas using a transversal filtering structure, phase encoded waveforms can be generated by programming the weights of the wavelength channels. This approach eliminates the need for RF signal generators for RF carrier generation or arbitrary waveform generators for phase encoded signal generation. A large number of wavelengths—up to 60—were provided by the microcomb source, yielding a high pulse compression ratio of 30. Reconfigurable phase encoding rates ranging from 2 to 6 Gb/s were achieved by adjusting the length of each phase code. This article demonstrates the significant potentials of this microcomb-based approach to achieve high-speed RF photonic phase encoding with low cost and footprint. [ABSTRACT FROM AUTHOR]

We report a photonic microwave and radio frequency (RF) fractional Hilbert transformer based on an integrated Kerr micro-comb source. The micro-comb source has a free spectral range (FSR) of 50 GHz, generating a large number of comb lines that serve as a high-performance multi-wavelength source for the transformer. By programming and shaping the comb lines according to calculated tap weights, we achieve both arbitrary fractional orders and a broad operation bandwidth. We experimentally characterize the RF amplitude and phase response for different fractional orders and perform system demonstrations of real-time fractional Hilbert transforms. We achieve a phase ripple of <0.15 rad within the 3-dB pass-band, with bandwidths ranging from 5 to 9 octaves depending on the order. The experimental results show good agreement with theory, confirming the effectiveness of our approach as a new way to implement high-performance fractional Hilbert transformers with broad processing bandwidth, high reconfigurability, and greatly reduced size and complexity. [ABSTRACT FROM AUTHOR]

Abstract: Lithium niobate on insulator (LNOI) technology is revolutionizing the lithium niobate industry, enabling higher performance, lower cost and entirely new devices and applications. The availability of LNOI wafers has sparked significant interest in the platform for integrated optical applications, as LNOI offers the attractive material properties of lithium niobate, while also offering the stronger optical confinement and a high optical element integration density that has driven the success of more mature silicon and silicon nitride (SiN) photonics platforms. Due to some similarities between LNOI and SiN, established techniques and standards can readily be adapted to the LNOI platform including a significant array of interface approaches, device designs and also heterogeneous integration techniques for laser sources and photodetectors. In this contribution, we review the latest developments in this platform, examine where further development is necessary to achieve more functionalities in LNOI integrated optical circuits and make a few suggestions of interesting applications that could be realized in this platform. [ABSTRACT FROM AUTHOR]

The article focuses on development of non-linear frequency mixing strategies to approach shift from the electromagnetic (EM) waves, and mentions use of Lithium niobate for frequency mixing due to material properties. Topics discussed include lithium niobate photonics flexibility in EM waves, integrated photonic circuits created by heterogeneous integration of active materials, and role of the confining waveguides in lithium niobate.

To overcome the limitation of direct etching waveguide fabrication, a silicon nitride thin film was deposited onto the surface of LNOI chip, where the SWGs were formed using CMOS-compatible etching processes developed by microelectronics industry. B Subwavelength Gratings b In article number 2200130, Yonghui Tian and colleagues experimentally demonstrate compact subwavelength grating (SWG) waveguides on a LNOI platform for on-chip mode and polarization manipulation. [Extracted from the article]

Mode and Polarization-Division Multiplexing Based on Silicon Nitride Loaded Lithium Niobate on Insulator Platform (Laser Photonics Rev. 16(1)/2022) B (De)Multiplexing Technologies b In article number 2100529, Yonghui Tian, Arnan Mitchell, Yikai Su, and co-workers experimentally demonstrated mode and polarization-division multiplexing on a thin-film lithium niobate on insulator (LNOI) platform. By introducing silicon nitride as a loading material atop the LNOI photonics chip, the devices can be integrated with high-speed electro-optic modulators to achieve high-capacity and low-cost photonic integrated circuits suitable for data communication applications, while avoiding the direct etching of lithium niobate. [Extracted from the article]

The theoretical analysis and experimental demonstration of a waveguide resonator are presented based on bound states in the continuum in an integrated photonic chip platform. The continuum has the form of a collimated beam of light which is confined vertically in a transverse electric (TE) mode of a silicon slab. The bound state is a discrete transverse‐magnetic (TM)‐like mode of a ridge on the silicon slab. The coupling between the slab and ridge modes results in a single sharp resonance at the wavelength where they phase match. This phenomenon is experimentally demonstrated on a silicon photonic chip using foundry‐compatible parameters and it is interfaced on‐chip to standard single‐mode silicon nanowire waveguides. The fabricated chip exhibits a single sharp resonance near 1550 nm with a line width of a few nanometers, an extinction ratio of 25 dB, and a thermal stability of 19.5 pm °C−1. It is believed that the demonstration of a resonance operating near a bound state in the continuum realized using guided wave components will form the basis of a new approach to on‐chip wavelength filtering and sensing applications. [ABSTRACT FROM AUTHOR]

In article number 1800149, Lin Chang and co‐workers demonstrate a gallium‐arsenide‐on‐insulator platform for integrated nonlinear photonics. Waveguides on this platform have high nonlinear coefficients, large index contrasts and low propagation losses. Harnessing those properties, a second harmonic generation with a record normalized efficiency is achieved. This work paves a way to ultra‐high performance nonlinear photonic integrated circuits. [ABSTRACT FROM AUTHOR]

Tremendous scientific progress has been achieved through the development of nonlinear integrated photonics. Prominent examples are Kerr frequency comb generation in microresonators, and supercontinuum generation and frequency conversion in nonlinear photonic waveguides. A high conversion efficiency is enabling for applications of nonlinear optics, including such broad directions as high‐speed optical signal processing, metrology, and quantum communication and computation. In this work, a gallium‐arsenide‐on‐insulator (GaAs) platform for nonlinear photonics is demonstrated. GaAs has among the highest second‐ and third‐order nonlinear optical coefficients, and the use of a silica cladding results in waveguides with a large refractive index contrast and low propagation loss for expanded designs of nonlinear processes. By harnessing these properties and developing nanofabrication with GaAs, a record normalized second‐harmonic efficiency of 13 000% W−1 cm−2 at a fundamental wavelength of 2 µm is reported. This work paves the way for high performance nonlinear photonic integrated circuits, which not only can transition advanced functionalities outside the lab through fundamentally reduced power consumption and footprint, but also enables future optical sources and detectors. A gallium‐arsenide‐on‐insulator platform for integrated nonlinear photonics is demonstrated on silicon substrate. Waveguides on this platform have high nonlinear coefficients, large index contrasts, and low propagation losses. By harnessing those properties, a second‐harmonic generation with a record‐normalized efficiency of 13 000% W−1 cm−2 is achieved. This work paves the way to high performance nonlinear photonic integrated circuits. [ABSTRACT FROM AUTHOR]