Ultracompact bandwidth-tunable filter based on subwavelength grating-assisted contra-directional couplers

Wang, Kangnian; Wang, Yuan; Guo, Xuhan; Zhang, Yong; He, An; Su, Yikai

doi:10.1007/s12200-020-1056-5

Cited by 8 publications

(4 citation statements)

References 24 publications

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“…In order to further improve the SNR, two injection‐locked lasers or coherent light sources such as stabilized optical frequency combs can be deployed to reduce the noise in the heterodyne signal mixing via photodetection. For the future development toward the miniaturization of the P‐WSF radar system, recent advances in photonic integration of key functional units such as on‐chip acousto‐optic frequency shifter [ 46 ] and versatile integrated optical passband filters [ 47 ] with sharp spectral roll‐off provide an important and promising technical basis for achieving compact P‐WSF radars. We would like to note that a microwave photonic radar using optical frequency shifting modulation of linearly chirp waveform generated by an ultra‐high‐speed benchtop arbitrary electric waveform generator and an intricately configured high‐speed electro‐optic modulator was reported, [ 22 ] based on a fundamentally different principle and configurations.…”

Section: Discussionmentioning

confidence: 99%

11‐GHz‐Bandwidth Photonic Radar using MHz Electronics

Liu

Zhang

Burla

et al. 2022

Laser & Photonics Reviews

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The ever-increasing demand for high resolution and real-time recognition in radar applications has fuelled the development of electronic radars with increased bandwidth, high operation frequency, and fast processing capability. However, the generation and processing of wideband radar signals increase the hardware burden on complex and high-speed electronics, limiting its capability for applications that demand high spatial resolutions. Progress is being made, photonics-assisted radars offer higher frequencies but still heavily rely on costly and sophisticated high-frequency electronic devices such as benchtop digital microwave waveform generators that fundamentally constrain the bandwidth and the practical utility. Here, for the first time, a photonics-based radar with >11 GHz bandwidth (exceeding 20 GHz without RF antenna bandwidth limitation) driven and processed by simple MHz-level-electronics-based acoustic-optic modulation is demonstrated, which radically eliminates the requirement for ultra-fast GHz-speed electronics for wideband radar signal generation and processing. This wideband radar achieves centimeter-level spatial resolution and a real-time imaging rate of 200 frames s −1 , allowing for high-resolution detection of rapidly moving blades of an unmanned aerial vehicle. This radar provides an important technological basis for next-generation broadband radars with greatly reduced system complexity essential to ubiquitous sensing applications such as autonomous driving, environmental surveillance, and vital sign detection.

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Section: Discussionmentioning

confidence: 99%

11‐GHz‐Bandwidth Photonic Radar using MHz Electronics

Liu

Zhang

Burla

et al. 2022

Laser & Photonics Reviews

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“…The benchtop EDFA can be replaced with a compact EDFA (such as ACL-PM-mini-EDFA-24) that can offer sufficient gain to offset the in-loop losses. On-chip components, such as AOM [48], [49], bandpass filter [50], and waveguide amplifier [51], are also promising to reduce the optical system's size further. A commercial data acquisition (DAQ) unit could be sufficient to simultaneously generate the RF driving signal and acquire the demodulated signal, therefore minimizing the system's electronic footprint.…”

Section: Discussionmentioning

confidence: 99%

Photonic Generation of 30 GHz Bandwidth Stepped-Frequency Signals for Radar Applications

Zhang

Liu

Eggleton

2022

J. Lightwave Technol.

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Wideband microwave signals with high timefrequency linearity for high-resolution radar applications can be optically generated using high-speed electronic waveform generators. Frequency-shifting modulation in an optical cavity provides an attractive approach to generate broadband microwave signals with reduced complexity requiring only MHz-level electronics. However, the in-loop signal instability and inter-pulse interference usually cause amplitude fluctuations, leading to limited signal-to-noise ratio and signal bandwidth. Here, we overcome these challenges and demonstrate, for the first time, the photonic generation of 30-GHz-wide stepped-frequency (SF) signals with 100 MHz frequency steps defined by an MHz-level electrical oscillator. We achieved this performance by mitigating the in-loop polarization scrambling and inter-pulse interference using a polarization-maintaining cavity and a high-extinction optical switch. This allows stable consecutive acousto-optic frequency-shifting modulation that significantly improves the signal-to-noise ratio. While achieving a bandwidth surpassing the state-of-the-art demonstrations based on wideband electronics, our approach alleviates the necessity for high-speed signal generators or wideband tunable lasers. To exemplify the utility, we systematically evaluate the signal quality and show its applications in radar imaging compared to those using electrical waveform generators.

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“…It can be mass produced for various applications such as LiDAR [5][6][7][8] and freespace optical communication [9]. To date, integrated OPAs have been achieved on various integrated platforms such as silicon (Si) [10][11][12][13][14][15][16][17], Si nitride (Si 3 N 4 ) [18], lithium niobate (LiNbO 3 ) [19], and indium phosphide (InP) [20]. Among them, Si is a desirable platform since it is fully compatible with the complementary metal oxide semiconductor (CMOS) fabrication process, allowing for integration with electronic controlling circuits [11,12].…”

Section: Introductionmentioning

confidence: 99%

Bidirectional high sidelobe suppression silicon optical phased array

Qiu¹,

Liu²,

Meng³

et al. 2023

Photon. Res.

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An optical phased array (OPA), the most promising non-mechanical beam steering technique, has great potential for solid-state light detection and ranging systems, holographic imaging, and free-space optical communications. A high quality beam with low sidelobes is crucial for long-distance free-space transmission and detection. However, most previously reported OPAs suffer from high sidelobe levels, and few efforts are devoted to reducing sidelobe levels in both azimuthal ( φ ) and polar ( θ ) directions. To solve this issue, we propose a Y-splitter-assisted cascaded coupling scheme to realize Gaussian power distribution in the azimuthal direction, which overcomes the bottleneck in the conventional cascaded coupling scheme and significantly increases the sidelobe suppression ratio (SLSR) in the φ direction from 20 to 66 dB in theory for a 120-channel OPA. Moreover, we designed an apodized grating emitter to realize Gaussian power distribution in the polar direction to increase the SLSR. Based on both designs, we experimentally demonstrated a 120-channel OPA with dual-Gaussian power distribution in both φ and θ directions. The SLSRs in φ and θ directions are measured to be 15.1 dB and 25 dB , respectively. Furthermore, we steer the beam to the maximum field of view of 25°×13.2° with a periodic 2λ pitch (3.1 μm). The maximum total power consumption is only 0.332 W with a thermo-optic efficiency of 2.7 mW/π .

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Ultracompact bandwidth-tunable filter based on subwavelength grating-assisted contra-directional couplers

Cited by 8 publications

References 24 publications

11‐GHz‐Bandwidth Photonic Radar using MHz Electronics

11‐GHz‐Bandwidth Photonic Radar using MHz Electronics

Photonic Generation of 30 GHz Bandwidth Stepped-Frequency Signals for Radar Applications

Bidirectional high sidelobe suppression silicon optical phased array

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