Multi-Plane Light Conversion: A Practical Tutorial

Author(s):

Zhang, Yuanhang & Fontaine, Nicolas K.

Abstract:

“Multi-plane light conversion (MPLC) has recently been developed as a versatile tool for manipulating spatial distributions of the optical field through repeated phase modulations. An MPLC Device consists of a series of phase masks separated by free-space propagation. It can convert one orthogonal set of beams into another orthogonal set through unitary transformation, which is useful for a number of applications. In telecommunication, for example, mode-division multiplexing (MDM) is a promising technology that will enable continued scaling of capacity by employing spatial modes of a single fiber. MPLC has shown great potential in MDM devices with ultra-wide bandwidth, low insertion loss (IL), low mode-dependent loss (MDL), and low crosstalk. The fundamentals of design, simulation, fabrication, and characterization of practical MPLC mode (de)multiplexers will be discussed in this tutorial.”

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Publication: arXiv
Issue/Year: arXiv, 2023
DOI: 10.48550/arXiv.2304.11323

Programmable 147 Tb/s (92 Gb/s xhspace0.167em16) optical wireless broadcasting system empowered by a single spatial light modulator and a modified RSS algorithm

Author(s):

You, Quan; Li, Chao; Xiao, Xi & Yu, Shaohua

Abstract:

“We have proposed and experimentally demonstrated a programmable multi-access-point optical wireless broadcasting system with ±15° field-of-view by employing a single spatial light modulator (SLM) and a modified rotated-splitting-SLM algorithm. The 16 access points are generated and arbitrarily distributed by the proposed continuous tunable broadcasting algorithm. The optical beams for each point carry 92-Gb/s PAM-4 optical signal and transmitted over 1 km standard single mode fiber and 1.2 m indoor free space distance, offering a total wireless capacity beyond 1.47 Tb/s. The measured results show that the proposed multi-access-points transmission system with ultra-high transmission capacity and reconfigurability can be used for future indoor wireless mobile networks.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 13; Pages 19373; 2021
DOI: 10.1364/oe.428752

Deep-learning-based high-resolution recognition of fractional-spatial-mode-encoded data for free-space optical communications

Author(s):

Na, Youngbin & Ko, Do-Kyeong

Abstract:

“Structured light with spatial degrees of freedom (DoF) is considered a potential solution to address the unprecedented demand for data traffic, but there is a limit to effectively improving the communication capacity by its integer quantization. We propose a data transmission system using fractional mode encoding and deep-learning decoding. Spatial modes of Bessel-Gaussian beams separated by fractional intervals are employed to represent 8-bit symbols. Data encoded by switching phase holograms is efficiently decoded by a deep-learning classifier that only requires the intensity profile of transmitted modes. Our results show that the trained model can simultaneously recognize two independent DoF without any mode sorter and precisely detect small differences between fractional modes. Moreover, the proposed scheme successfully achieves image transmission despite its densely packed mode space. This research will present a new approach to realizing higher data rates for advanced optical communication systems.”

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Publication: Scientific Reports
Issue/Year: Scientific Reports, Volume 11; Number 1; 2021
DOI: 10.1038/s41598-021-82239-8

High-Resolution Tunable Filter With Flexible Bandwidth and Power Attenuation Based on an LCoS Processor

Author(s):

Yunshu Gao, Genxiang Chen, Xiao Chen, Qian Zhang, Qiao Chen, Ce Zhang, Kai Tian, Zhongwei Tan and Chao Yu

Abstract:

“High-resolution optical filters and wavelength selective switches are the essential components in the current and next-generation dynamic optical networks. A high-resolution programmable filter for telecom application is proposed and experimentally demonstrated based on a 4 k phase-only liquid crystal on silicon (LCoS) spatial light modulator. The tuning resolution, bandwidth, and power attenuation for each wavelength channel can be modulated independently by remote software control. For each channel, the center wavelength is tuned in the step of 7.5 ± 1 pm and the 3 dB bandwidth achieves from 10 GHz to 3 THz. Furthermore, by multi-casting hologram design techniques for an LCoS, the power attenuation is adjusted from 0 dB to 30 dB with the step of 0.1 dB. The insertion loss is less than 6 dB across the entire C-band and 1.8 dB of it can be further improved by adopting an LCoS chip with smaller reflection loss. ”

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Publication: IEEE Photonics Journal
Issue/Year: Volume: 10 Issue: 6 (2018)
DOI: 10.1109/JPHOT.2018.2876347

Demonstration of a 3 texttimes 4 tunable bandwidth WSS with tunable attenuation using compact spatial light paths

Author(s):

Xie, Dequan; Liu, Zichen; You, Quan & Yu, Shaohua

Abstract:

“M × N wavelength selective switch (WSS) is a core component to address wavelength conflict in an optical switching node. In this paper, we design and experimentally demonstrate a performance enhanced 3 × 4 tunable bandwidth WSS (TBWSS) with tunable attenuation across the full C-band, and using compact spatial light paths. Wavelength channels from any input optical fiber port can be switched into any output optical fiber port with best insertion loss (IL) of 8.4 dB and worst IL of 12.5 dB. The attenuation tuning range can reach up to 35 dB. Compared to previous demonstrations, more than 2 dB IL improvement is achieved. Based on the proposed compact spatial light paths, the number of input and output ports can be easily extended to 10 and 20, respectively.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 25; Number 10; Pages 11173; 2017
DOI: 10.1364/oe.25.011173

LCoS-Based Wavelength-Selective Switch for Future Finer-Grid Elastic Optical Networks Capable of All-Optical Wavelength Conversion

Author(s):

Xie, Dequan; Wang, Danshi; Zhang, Min; Liu, Zichen; You, Quan; Yang, Qi & Yu, Shaohua

Abstract:

“A finer-grid wavelength-selective switch (WSS) based on liquid crystal on silicon
is proposed, fabricated, and demonstrated. Based on the cost-effective method, namely
combined lenses technique, the focal length is increased so that both the bandwidth setting
resolution and grid granularity is improved from 12.5 to 6.25 GHz compared with the conventional WSS. To demonstrate its utility, we apply this finer-grid WSS to a reconfigurable optical
add/drop multiplexer structure and an all-optical wavelength conversion (AOWC) module.
To enable a finer-grid WSS, the performance of a finer-grid elastic optical network (EON)
capable of AOWC is also investigated. Different from the conventional AOWC scheme for
fixed-grid WDM networks, we propose and experimentally demonstrate a four-wave-mixingbased AOWC module specifically for EON. In addition to physical experiments, an optical
network’s control and management scheme corresponding to the designed physical scenario
is also investigated. Experimental and simulation results show that the proposed method
achieves higher spectrum efficiency, lower blocking probability, finer switching granularity,
and higher conversion resolution”

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Publication: IEEE Photonics Journal
Issue/Year: IEEE Photonics Journal, Volume 9; Number 2; Pages 1–12; 2017
DOI: 10.1109/jphot.2017.2671436