Ultralow‐Loss Silicon Photonics beyond the Singlemode Regime

Zhang, Long; Hong, Shihan; Wáng, Yì; Yan, Hao; Xie, Yiwei; Chen, Tangnan; Zhang, Ming; Yu, Zejie; Shi, Yaocheng; Liu, Liu; Dai, Daoxin

doi:10.1002/lpor.202100292

Cited by 76 publications

(31 citation statements)

References 56 publications

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“…This problem can be solved by further boosting the Q factor of the microresonator in the integrated OEO. Therefore, the waveguide propagation loss should be further reduced by optimizing the design of the high- Q MRR 31 , 32 or by thermal oxidation of the Si waveguides 33 . Moreover, a fully integrated OEO, converging optical and electrical circuits, aims to develop chip-scale microwave photonic systems for generating microwave signals with low phase noise and wideband tunability.…”

Section: Resultsmentioning

confidence: 99%

On-chip tunable parity‐time symmetric optoelectronic oscillator

Wang

Xiao²,

Xu³

et al. 2023

Adv. Photon. Nexus

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Parity-time (PT) symmetry breaking offers mode selection capability for facilitating single-mode oscillation in the optoelectronic oscillator (OEO) loop. However, most OEO implementations depend on discrete devices, which impedes proliferation due to size, weight, power consumption, and cost. In this work, we propose and experimentally demonstrate an on-chip tunable PT-symmetric OEO. A tunable microwave photonic filter, a PT-symmetric mode-selective architecture, and two photodetectors are integrated on a silicon-on-insulator chip. By exploiting an on-chip Mach-Zehnder interferometer to match the gain and loss of two mutually coupled optoelectronic loops, single-mode oscillation can be obtained. In the experiment, the oscillation frequency of the on-chip tunable PT-symmetric OEO can be tuned from 0 to 20 GHz. To emulate the integrated case, the OEO loop length is minimized, and no extra-long fiber is used in the experiment. When the oscillation frequency is 13.67 GHz, the single-sideband phase noise at 10-kHz offset frequency is −80.96 dBc∕Hz and the side mode suppression ratio is 46 dB. The proposed on-chip tunable PT-symmetric OEO significantly reduces the footprint of the system and enhances mode selection.

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Section: Resultsmentioning

confidence: 99%

On-chip tunable parity‐time symmetric optoelectronic oscillator

Wang

Xiao²,

Xu³

et al. 2023

Adv. Photon. Nexus

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“…Thus, the optimal optical delay line would introduce less than 1 dB extra loss while significantly enhancing the ATR. Moreover, using multimode waveguides, the waveguide propagation loss can be further reduced, down to 0.065–0.25 dB/cm. , The time delay between the cavities can also be improved by engineering the connecting waveguide’s dispersion, e.g., by coupling the connecting waveguide with a passive cavity. The bandwidth of operation can be improved by incorporating efficient thermal tuners on the MRMs to tune the resonance locally.…”

Section: Discussionmentioning

confidence: 99%

Nonreciprocal Light Propagation in a Cascaded All-Silicon Microring Modulator

et al. 2021

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Optical isolators and circulators are critical building blocks for large-scale photonic integrated circuits. Among the several methods proposed to realize such nonreciprocal devices, including heterogeneous integration with garnet-based materials or using nonlinearities, dynamic modulation of the waveguide properties is a potentially practical and easily accessible method. However, most proposals relying on this method rely on modulators with a very large footprint, limiting their practical applicability. This paper overcomes this issue by presenting a method to achieve nonreciprocal optical transmission taking advantage of compact ring modulators. We use a cascaded system of microring modulators with a footprint as small as 15 μm × 220 μm and propose that, by tuning the relative time delay between the RF driving signals and the optical delay between the modulators, nonreciprocal transmission can be achieved. We present a detailed theoretical analysis of our design and investigate the origin of the asymmetric transmission. The modulators were designed and fabricated on IMEC's Silicon-on-Insulator platform iSiPP50G. We achieve a 16 dB difference between forward and backward optical signals at a driving voltage (V pp ) of 8 V at 6 GHz. Moreover, we analyze the impact of fabrication imperfections on the device performance. Our work leads to a significant reduction in device footprint compared to formerly explored solutions using dynamic modulation and is well suited for monolithic integration with photonic integrated circuits.

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“…For waveguides this wide, the field interaction with the sidewall roughness is greatly minimized, as it can be seen in Fig. 1.c, however the losses are still limited by the sidewall roughness, which could be improved by optimizing the fabrication methods [15]. A different configuration to avoid HOM excitation used MM concentric racetracks combined with a broadband directional coupler based on a pulley configuration demonstrating a Q-factor of 1.4 × 10 6 over a wavelength range from 1240 to 1680 nm.…”

Section: Introductionmentioning

confidence: 99%

Ultra-High-Q Racetrack Resonators on Thick SOI Platform Through Hydrogen Annealing Smoothing

Marin

Bera

Cherchi

et al. 2023

J. Lightwave Technol.

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We implemented a hydrogen annealing based postprocessing technique as a tool to improve the sidewall roughness of 3 μm thick silicon-on-insulator (SOI) waveguides and demonstrated ultra-high-Q factors on racetrack resonators leveraging on the propagation loss reduction achieved through the smoothing process. The designed racetracks are based on a combination of rib waveguides and strip-waveguide-based Euler bends. We measured intrinsic quality factors of 14×10 6 for a racetrack with a footprint of ~5.5 mm 2 and 10.7×10 6 for a smaller racetrack with footprint of ~1.48 mm 2 . The estimated propagation loss for the rib waveguides was ~2.7 dB/m, representing a ×3 reduction respect to the previously measured losses of 3 μm thick SOI rib waveguides treated with thermal oxidation smoothing. Overall, the post-processing technique allowed to significantly reduce the sidewall roughness without altering the geometry of the waveguides, unlike in sub-micron scale SOI platforms, making it an attractive solution for applications demanding ultra-low losses.

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Ultralow‐Loss Silicon Photonics beyond the Singlemode Regime

Cited by 76 publications

References 56 publications

On-chip tunable parity‐time symmetric optoelectronic oscillator

On-chip tunable parity‐time symmetric optoelectronic oscillator

Nonreciprocal Light Propagation in a Cascaded All-Silicon Microring Modulator

Ultra-High-Q Racetrack Resonators on Thick SOI Platform Through Hydrogen Annealing Smoothing

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