Fast and wide-range optical beam steering with ultralow side lobes by applying an optimized multi-circular optical phased array

Hong

et al. 2021

Sci Rep

We designed and fabricated a photonic crystal surface emitting laser (PCSEL) with vertically integrated diffractive optical elements on their top to study the mechanism of static beam steering on a single chip. The deflected output beam by the self-formed periodic ITO cladding layer of the PCSEL can be further steered by changing the grating period and azimuthal angle of the diffractive gratings relative to the photonic crystal. Through the analysis of photonic band structure and lasing characteristics, the periodic ITO structure is coupled to the photonic crystal band, whereas the integrated grating serves the diffractive function only. The findings pave the way for the design of PCSELs enabling single or multiple output beam with varying direction capability. This type of laser is regarded as an ideal light source for various applications, such as light detection and ranging and three-dimensional sensing systems.

Section: Vertically Integrated Diffractive Gratings On Photonic Crystal Surface Emitting Lasersmentioning

confidence: 99%

Vertically integrated diffractive gratings on photonic crystal surface emitting lasers

Hong

et al. 2021

Sci Rep

IEEE Trans. Netw. Serv. Manage.

“…1 where optical transceivers of ESs are connected to CS transceivers located at the top. WDM-FSO links can be implemented by photonic integrated circuits (PIC) [35] or photo-diode array [36] based transmitters to steer the lightbeam to the photodiode receivers. Since transceivers are not required to change their direction after the setup, an alternative approach is setting gimbals atop the racks and directing transmitter and receiver towards each other 1 .…”

Section: A Node Architecture and Network Topologymentioning

confidence: 99%

LightFDG: An Integrated Approach to Flow Detection and Grooming in Optical Wireless DCNs

AlGhadhban

Çelik

Shihada

et al. 2020

LightFDG is an integrated approach to flow detection (FD) and flow grooming (FG) in optical wireless data center networks (DCNs), which is interconnected via wavelength division multiplexing (WDM) based free-space optical (FSO) links. Since forwarding bandwidth-hungry elephant flows (EFs) and delay-sensitive mice flows (MFs) on the same path can cause severe performance degradation, the LightFDG optically grooms flows of each class into rack-to-rack (R2R) flows. Then, R2R-MF and R2R-EF flows are separately forwarded over lightpaths of separate MF and EF virtual topologies, respectively. Lightpaths are provisioned by jointly determining the capacity and route based on flows' arrival rate, size, and completion time request. To prevent EFs from congesting the MF lightpaths, high speed and accurate flow-detection mechanisms are also necessary for classifying EFs as soon as possible. Therefore, a fast-lightweight-andaccurate flow detection framework is developed by leveraging the transmission control protocol (TCP) behaviors. The proposed FD scheme has the flexibility of being implemented as in-network or centralized to classify flows of modifiable and unmodifiable hosts, respectively. Since the centralized scheme incurs considerable overhead, the processing and communication overhead is also mitigated by proposed techniques. Numerical results show that LightFDG outperforms traditional load balancers by about 3f or EFs and 10ˆfor MFs. Along with the developed overhead mitigation methods, the centralized scheme is shown to provide up to 62ˆlower overhead with 100% accuracy and with about 224ˆhigher detection speeds than the existing centralized solutions.

“…To date, integrated OPAs typically use one-dimensional (1D) linear arrays [ 7 , 8 , 9 , 10 , 11 , 12 , 13 ] and two-dimensional (2D) planar arrays with either rectangular [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ] or circular [ 21 , 22 , 23 , 24 , 25 , 26 ] arrangements. For 1D arrays, wavelength-dependent grating nano-antennas are typically used for beam steering.…”

Section: Introductionmentioning

confidence: 99%

“…Circular OPAs are promising alternatives to 1D linear and 2D rectangular arrays, where a circular array can offer a large steering range and high resolution concurrently [ 21 , 22 , 23 , 24 , 25 , 26 ]. For circular OPAs, the high resolution and wide scanning can be obtained with efficient sidelobe suppression.…”

Section: Introductionmentioning

confidence: 99%

Circular Optical Phased Arrays with Radial Nano-Antennas

et al. 2022

On-chip optical phased arrays (OPAs) are the enabling technology for diverse applications, ranging from optical interconnects to metrology and light detection and ranging (LIDAR). To meet the required performance demands, OPAs need to achieve a narrow beam width and wide-angle steering, along with efficient sidelobe suppression. A typical OPA configuration consists of either one-dimensional (1D) linear or two-dimensional (2D) rectangular arrays. However, the presence of grating sidelobes from these array configurations in the far-field pattern limits the aliasing-free beam steering, when the antenna element spacing is larger than half of a wavelength. In this work, we provide numerical analysis for 2D circular OPAs with radially arranged nano-antennas. The circular array geometry is shown to effectively suppress the grating lobes, expand the range for beam steering and obtain narrower beamwidths, while increasing element spacing to about 10 μm. To allow for high coupling efficiency, we propose the use of a central circular grating coupler to feed the designed circular OPA. Leveraging radially positioned nano-antennas and an efficient central grating coupler, our design can yield an aliasing-free azimuthal field of view (FOV) of 360°, while the elevation angle FOV is limited by the far-field beamwidth of the nano-antenna element and its array arrangement. With a main-to-sidelobe contrast ratio of 10 dB, a 110-element OPA offers an elevation FOV of 5° and an angular beamwidth of 1.14°, while an 870-element array provides an elevation FOV up to 20° with an angular beamwidth of 0.35°. Our analysis suggests that the performance of the circular OPAs can be further improved by integrating more elements, achieving larger aliasing-free FOV and narrower beamwidths. Our proposed design paves a new way for the development of on-chip OPAs with large 2D beam steering and high resolutions in communications and LIDAR systems.