Collimation Characteristics of Planar Microlens for Parallel Optical Interconnect

Inspired by the structure of natural compound eyes, a liquid tunable-focus microlens array omnidirectionally arranged on a transparent hemispherical dome is demonstrated. Benefiting from the dome structure, this microlens array exceeds traditional planar ones with wide field of view (FOV). Each microlens in this microlens array was formed by a curved water-oil meniscus. The focal length of the microlenses could be individually tuned by a thermo-responsive hydrogel microactuator. Planar and hemispherical microlens arrays were tested and the focal length of the hemispherical microlens array varied from 3 mm to 32 mm. Focused images from the microlens arrays were recorded by a CCD-coupled stereoscope.

For the shortcomings of traditional data communication electronic mode and bus interface, optical fiber communication electronic technology and compact peripheral component interconnect (CPCI) bus interface mode with industry standard are adopted to design a kind of optical fiber communication electronic data transmission mode. The optical fiber communication electronic board based on CPCI bus constitutes a novel optical fiber communication electronic system. In the process of hardware design, the small form-factor pluggable (SFP) transceiver module is used to convert the photoelectric signal and complete the transmission of optical fiber data. Regarding the existence of differential signal in high-speed serial circuit of electronic board, the wiring is reasonably arranged. The hardware test platform of optical fiber communication electronic system is built based on PCI9054 CPCI bus and industrial personal computer (IPC) communication electronics. FPGA with embedded high-speed serial transceiver module is adopted to design the hardware logic function. Binary gray code is used to count. FIFO protocol and Aurora protocol are supported. Protocol IP core is customized to realize the full duplex electronic communication of high-speed data. Considering the loss problem of the system, the grey model GM(1, 1), ARIMA model and Elman neural network are employed as the big data level research scheme, which are combined into the loss prediction model according to a certain proportion. In the experiment, the test of DMA data reading and writing function is designed, and the embedded highspeed transceiver module and optical fiber communication electronic logic function are simulated. The results show that the symbol error rate (SER) is always 0, and the low-pass filtering characteristics of the channel are effectively compensated, which makes the signal quality stabler. Compared with the single big data level research scheme, the combined model has smaller prediction error and higher prediction accuracy.

In this paper, a bidirectional optical module based on a stacked planar optical circuit (SPOC) concept to perform a wavelength division multiplexing (WDM) function is described. The module consists of an optical chip which incorporates planar microlens (PML) arrays and nonpolarizing 1.31/1.55 µm WDM dielectric-multilayer filters. Module design and theoretical estimation of loss tolerance were conducted. From preliminary experiments, the feasibility of SPOC modules was confirmed. A fabricated WDM filter showed a small polarization-dependent loss (PDL) of about 0.48 dB and 0.05 dB for the wavelengths of 1.31 µm and 1.55 µm, respectively. Channel crosstalk and PDL for the SPOC module were characterized by means of discrete filter devices. For the 1.55 µm downstream (1.31 µm downstream/upstream) channel, a crosstalk as low as -40 dB (-26 dB) and a PDL less than 0.23 dB (0.53 dB) were achieved.

Nowadays, the coherent optical communication system plays an important role in communication field because of large capability and bandwidth. A coherent optical communication, based on high-order modulation and digital signal processing technologies, consists of optical transmitters, optical fiber lines, optical amplifiers and optical receivers. In the high-speed coherent optical communication system, the phase noise from the transmitter laser and the local oscillator laser can significantly degrade the performance of the signal transmission and detection, especially for the systems using high-order modulation format, such as m-ary phase shift keying (mPSK) and m-ary quadrature amplitude modulation (m-QAM). Therefore, investigations on laser phase noise compensation algorithm based on digital signal processing technologies has become more and more significant. In this work, a multi-ring carrier phase recovery algorithm is developed for compensating the laser phase noise in optical fiber communication systems using high-order modulation formats. Degradations on the performance of communication systems due to the laser phase noise have been investigated. The system performance using the proposed algorithm and the conventional Viterbi-Viterbi algorithm were also evaluated in 9-channel and 15- channel, 32-Gbaud, Nyquist-spaced QPSK, 16-QAM, 64-QAM and 256-QAM coherent transmission systems with considering the impact of the laser phase noise. It is found that the phase noise leads to stricter constraints on the linewidths of transmitter-side and receiver-side lasers, and it can greatly degrade the achievable information rates in communication systems. Besides, compared to the conventional Viterbi-Viterbi algorithm, which is usually applied in the QPSK system, our proposed algorithm can also well mitigate the laser phase noise in 16-QAM, 64-QAM and 256-QAM optical communication systems.
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As human society to the information in the process of moving and growing demand for bandwidth communications capacity, the optical of new modulation formats increasingly attention and quickly play an important role in optical communications. How can the system bit error rate within a certain degree of stability while still maintaining high-speed long-distance dispersal system, has been a popular issue is the optical communications industry. Starting from the optical modulation format herein, the generation process of the system introduced various optical signal modulation format, the optical signal through the optical fiber was studied and the performance of the simulation, on the basis of the design of advanced optical modulation formats in an optical fiber communication system .

Digital coherent optical communication technologies have shown superior performance in supporting high-bit-rate optical communications, including high fiber chromatic dispersion (CD) and polarization mode dispersion (PMD) tolerance, and high spectral efficiency. We review the typical system design and principles of dual-polarization digital coherent optical communications, and further show a new dual-stage cascaded frequency offset estimator in achieving very high performance.

Supported by LCoS based 7-core fiber and multichannel transmitter, we experimentally demonstrate a 120Gb/s/λ intelligent bidirectional high-speed beam-steering optical wireless communication system with field-of-view of 7.0°×7.2° over 3.2 m within SD-FEC limit of 2.4 ×10-2.

The present situation in high-speed wireless data communications is examined. While there is growing demand for wireless bandwidth, the most pressing problem affecting this situation today is the attempt to increase bandwidth by using the same technology with tricks - rather than by using innovation. Opportunities for innovation are quite good with higher carrier frequencies, since these enable simplicity and low power consumption and opening the door to truly portable wireless peer-to-peer (WP2P) networking. Numerous challenges exist in technology and design methods; however, meeting these intellectual challenges is the only route to new and exciting wireless data technologies.

Decision feedback equalization (DFE) is a popular technique to counteract inter-symbol interference (ISI) in high-speed backplane data communications. Quarter-rate clock timing for DFE circuit design is proposed to alleviate the speed requirement of the clock timing. A receiver implemented in 0.18-/spl mu/m CMOS technology demonstrates 6.25Gb/s and 8Gb/s operation over a 34" FR4 backplane.

At present, optical fiber communication systems are developing in the direction of large capacity, high speed, long distance, etc., making nonlinear effects and polarization mode dispersion (PMD) and other optical fiber performance defects that were negligible for low-rate systems become the main factors limiting system upgrades and transmission distances. Polarization mode dispersion is an important factor affecting the performance of optical fiber communication systems, and it has become one of the main obstacles to the development of high-speed and long-distance optical fiber communication systems. It can cause pulse widening in the digital transmission system, thereby limiting the transmission rate of the system. Therefore, the influence of polarization mode dispersion on the transmission system and the compensation method are analyzed in this paper.

The performance degradation incurred by unwanted external reflections in high-speed digital optical communication systems using intensity-modulated single-longitudinal-mode laser diodes is investigated by numerical simulation of the rate equations. The effects of intensity modulation on the chaotic behavior in the laser output are examined and performance estimates for 0.5, 2.5, and 5 Gb/s systems are made. For example, it is found that to incur less than 0.25-dB power penalty in a 2.5-Gb/s system using a positive-intrinsic-negative photodetector, the reflected light in the laser pigtail should be at least 36 dB below that of the transmitted light.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The exponential growth of data in the information era has pushed conventional optical communication technology to its limitations, including inefficient spectral utilization, slow data rate, and inherent security vulnerabilities. Here, a transformative high-speed organic spectral wireless communication (SWC) technology enabled by a flexible, miniaturized, and high-performance organic hyperspectrometer is proposed that integrates ultrahigh-speed data transmission with hardware-level encryption. By synergistically combining organic photodetector arrays with tunable responsivities and spectral-tunable organic filters, the organic hyperspectrometer achieves a broad spectral detection range of 400 to 900 nm, resolution of 1.08 nm, accuracy of 0.60 nm, and response time of 684 ns. Unlike prior optical wireless communication systems, the organic hyperspectrometer-based SWC platform uniquely decodes high-speed encrypted data at the hardware level, which is a breakthrough in secure, high-speed, and high-capacity communication. Harnessing the full visible-to-near-infrared spectrum, the SWC system achieves a theoretical data rate of 9.1 Gbits s-1, ranking as the highest-speed organic optical communication system. Furthermore, the intrinsic flexibility and bandgap-tunability of organic materials enable unparalleled portability, adaptability, and scalability of organic SWC, establishing a scalable framework for terahertz-scale data transmission. These advancements mark a pivotal leap toward secure, high-speed, and ultracompact optical networks for the future data- and AI-driven era.

High-speed optical wireless communication (OWC) systems based on light-emitting diode (LED), such as Li-Fi, are promising solutions for the looming spectrum crisis in 6G wireless communications. OWCs typically extend the RF spectrum by harnessing the visible light and infrared spectra, but the recent advancements in deep-ultraviolet (DUV) LED device technology allow us to further extend the OWC spectrum down to the DUV range, namely the solar-blind band. This talk reviews the recent progress of the high-speed OWCs based on DUV-LEDs including Gbps-class transmission demonstrations in direct sunlight and analyses on the microscopic structural and optical characteristics of high-speed AlGaN-based LEDs.

In this work, A lateral PIN diode is fabricated based on the RF-SOI substrate. The diode is further used in UV photodetection and high-speed optical communication. It exhibits excellent linearity under various light intensity. The response spectrum of the photodiode shows UV-enhanced characteristics and its quantum efficiency reaches up to 89% at wavelength of 300nm. Thanks to the RF-SOI substrate which reduces the parasitic capacitance dramatically, the capacitance of the fabricated photodiode is as low as 0.4pF at −1V bias. The demonstrated photodiode based on RF-SOI substrate might be attractive for high speed optical communication system using short wavelength light.

Communication underwater is severely limited when compared to communications in air because water is essentially opaque to electromagnetic radiation except in the visible band. Even in the visible band, light penetrates only a few hundred meters in the clearest waters and much less in waters made turbid by suspended sediment or high concentrations of marine life. Consequently, acoustic techniques have been developed for underwater communication systems and now represent a relatively mature and robust technology. Acoustic systems are capable of long range communication, but offer limited data rates and significant latency (due to the speed of sound in water). We are developing an optical communication system that complements and integrates with existing acoustic systems resulting in an underwater communications capability offering high data rates and low latency when within optical range combined with long range and robustness of acoustics when outside of optical range. Amongst a wide array of applications, this combination of capabilities will make it possible to operate self-powered ROVs from support vessels or platforms without requiring a physical connection to the ROV. Such a capability will help simplify operations and potentially reduce costs through the use of less capable surface vessels. New deployment strategies may offer game-changing opportunities within all areas of undersea activities. For example, rapid event response will be enhanced and repair and maintenance of the emerging ocean observatory infrastructure will become more cost effective. Such through-water communications will likewise enable exchange of large data files from fixed sensors using AUVs (or ROVs) as data mules, shuttling real-time video from untethered vehicles for inspection, identification, and other related operations. Interconnectivity for dense arrays of underwater sensors without the need for expensive and difficult to install undersea cables is also possible. An unmanned battery operated vehicle, dedicated to a subsea node, that can be wirelessly operated though a combination of acoustic and optical communications, will be an important asset for both scientific exploration and commercial applications. We have demonstrated robust multi-point, low power omnidirectional optical communications over ranges of 100 meters at data rates up to 10 mega bits per second using a few tens of Watts of battery power with small, inexpensive transmitters and receivers. During the next few years, we will be exploring applications of this new technology directly in support of ongoing science and engineering programs. High-speed underwater optical communication is an enabling technology that has many potential applications in a range of environments from the deep sea to coastal waters. This development effort will enhance infrastructure for scientific research and commercial use by providing technology to efficiently communicate between surface vessels, underwater vehicles and seafloor infrastructure.