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Simultaneous transmission of fifth-generation (5G) millimeter-wave (MMW) and sub-THz signals through a fiber-free-space optical (FSO)-5G new radio (NR) converged system is successfully achieved. It is an inventive demonstration that utilizes a cross medium of optical fiber, optical wireless, and RF wireless to enhance the aggregate transmission rate to 60 Gb/s. We transmitted 20 Gb/s in the 50-GHz MMW, 100-GHz sub-THz, and 150-GHz sub-THz bands at the same time through the seamless fiber-FSO-5G NR convergence, comprising 20-km single-mode fiber (SMF), 500-m optical wireless, and 2-m (50-GHz MMW)/1-m (100-GHz sub-THz)/0.5-m (150-GHz sub-THz) 5G wireless transmissions. Sufficiently low bit error rate (< forward error correction criterion of 3.8×10−3) and error vector magnitude (

A bi-directional fiber-free-space optical (FSO)-fifth-generation (5G) millimeter-wave (MMW)/5G new radio (NR) sub-THz convergence with intensity-modulated downlink 40 Gbit/s/100 GHz 5G NR sub-THz signals (x- and y-polarizations), and phase-modulated uplink 10 Gbit/s/28 GHz and 10 Gbit/s/24 GHz 5G MMW signals is established practicably, by adopting a parallel/orthogonally polarized dual-carrier mechanism, phase modulators, and remote injection locking distributed feedback laser diodes (DFB LDs) for demonstration. It is a pioneering work to realize a bi-directional fiber-FSO-5G MMW/5G NR sub-THz convergence for providing high downlink/uplink traffic capacity with accepted transmission performance. Through 20 km single-mode fiber transmission, 500 m free-space link, and 1 m/4 m RF wireless transport, impressively low bit error rate of 10−9 and accepted PAM4/NRZ eye diagrams are acquired. Such established bi-directional fiber-FSO-5G MMW/5G NR sub-THz convergence accelerates a feasible solution that can afford high traffic capacity with qualified transmission performance, and develops the state achieved by the incorporation of optical fiber network with FSO-5G MMW/5G NR sub-THz convergence. It discloses a brilliant convergence developed for bi-directional high-speed and long-reach transmission with given transmission performance. [ABSTRACT FROM AUTHOR]

A flexible bidirectional fiber-free-space optical (FSO)-fifth-generation (5G) wireless convergent system with 1-Gb/s/4.5-GHz sub-6 GHz and 10-Gb/s/28-GHz millimeter-wave (MMW) (downstream), as well as 10-Gb/s/24-GHz MMW (upstream) 5G hybrid data signals is built, employing a vertical cavity surface emitting laser (VCSEL)-based wavelength selector and a remotely injection-locked distributed feedback laser diode (DFB LD) for presentation. It is the first to adopt a VCSEL-based wavelength selector to adaptively provide 5G applications and an injection-locked DFB LD to perform a phase modulation-to-intensity modulation transformation with an optical-to-electrical conversion. Good bit error rate performance and acceptable eye diagrams are achieved over 25 km single-mode fiber transport, 600 m FSO link, and 10 m/4 m RF wireless transmission. Such demonstrated fiber-FSO-5G wireless convergent system is a promising one toward optical-based long-haul networks at comparatively high-speed operations. It exhibits an excellent convergence not only due to its development for incorporating optical fiber with optical/5G wireless networks, but also due to its enhancement for flexible two-way high-speed and long-haul communications. [ABSTRACT FROM AUTHOR]

A bidirectional free-space optical (FSO) communication through a 600-m free-space transmission is built, employing a phase modulation (PM) scheme and a remotely injection-locked distributed feedback laser diode (DFB LD) for presentation. With optimum injection locking, a DFB LD is excellent for duplex transceiver operations. An injection-locked DFB LD not only operates as a PM-to-intensity modulation converter with an optical detector, but also functions as an upstream optical carrier. To be the first one of employing a remotely injection-locked DFB LD to detect a phase-modulated 25-Gb/s/25-GHz four-level pulse amplitude modulation (PAM4) passband signal, the DFB LD with remote injection locking is successfully intensity-modulated with an upstream 25-Gb/s non-return-to-zero (NRZ) signal. Good bit error rate performance and clear PAM4/NRZ eye diagrams show that this FSO communication can use a remotely injection-locked DFB LD to detect the downstream phase-modulated PAM4 signal and concurrently deliver an upstream intensity-modulated NRZ signal. This bidirectional 25-Gb/s/25-GHz (downstream)/25-Gb/s (upstream) FSO communication is prominent due to its enhancement in two-way high-speed optical wireless communications. [ABSTRACT FROM AUTHOR]

A full-duplex self-recovery optical fibre transport system is proposed on the basis of a novel passive single-line bidirectional optical add/drop multiplexer (SBOADM). This system aims to achieve an access network with low complexity and network protection capability. Polarisation division multiplexing technique, optical double-frequency application and wavelength reuse method are also employed in the transport system to improve wavelength utilisation efficiency and achieve colourless optical network unit. When the network comprises a hybrid tree–ring topology, the downstream signals can be bidirectionally transmitted and the upstream signals can continuously be sent back to the central office in the reverse pathways due to the remarkable routing function of the SBOADM. Thus, no complicated optical multiplexer/de-multiplexer components or massive optical switches are required in the transport system. If a fibre link failure occurs in the ring topology, then the blocked network connections can be recovered by switching only a single optical switch preinstalled in the remote node. Simulation results show that the proposed architecture can recover the network function effectively and provide identical transmission performance to overcome the impact of a breakpoint in the network. The proposed transport system presents remarkable flexibility and convenience in expandability and breakpoint self-recovery. [ABSTRACT FROM AUTHOR]

Four-switch current sensorless control for three-phase four-switch converter with power factor correction (PFC) function is presented in this letter. In comparison with conventional multiloop control methods, the proposed control strategy requires sensing of two line voltages and two capacitor voltages only to achieve PFC function. As there is no sensing current, the proposed sensorless control scheme reduces the cost and complexity of design. The performance of the proposed control is validated by its implementation in digital signal processing (DSP) TMS320F28335, and the result shows that the proposed scheme is able to provide comparable PFC performance without sensing current. [ABSTRACT FROM AUTHOR]

A wavelength-division-multiplexing (WDM) four-level pulse amplitude modulation (PAM4) free-space optical (FSO)–underwater wireless optical communication (UWOC) integrated system with a channel capacity of 100 Gb/s is proposed and attainably demonstrated. Analytic results reveal that 1.8-GHz 405-nm blue-violet-light and 1.7-GHz 450-nm blue-light laser diodes (LDs) with two-stage light injection and optoelectronic feedback techniques are competently adopted for 100 Gb/s PAM4 signal transmission through a 500-m free-space transmission with 5-m clear ocean underwater link. Combining dual-wavelength WDM scenario with PAM4 modulation, the channel capacity of FSO–UWOC integrated systems is significantly enhanced with an aggregate transmission rate of 100 Gb/s (25 Gbaud PAM4/wavelength × 2 wavelengths). With doublet lenses in FSO, laser beam reducer and transmissive spatial light modulator in UWOC, a sufficiently low bit error rate of 10−9 and acceptable PAM4 eye diagrams are acquired. This demonstrated 100 Gb/s PAM4 FSO–UWOC integrated system with a WDM scenario is advantageous for the enhancement of a high-speed optical wireless link with long-reach transmission. [ABSTRACT FROM AUTHOR]

The interleaved voltage-doubler boost converter strategy exhibits a very good performance, namely, in a low conduction loss, an acceptable switch stress, a fast transient response, and a very high power density. However, the bottleneck for application in the interleaved topology lies in the limit of operating duty ratio. In this article, an intrinsic current-balancing control method to achieve full operating range in duty ratio is proposed, and it can be easily implemented by including a voltage limiter to the conventional control configuration. With this novel design, both voltage-doubler and the current-balancing characteristics can be achieved within full range in duty cycle without any current sensor. The proposed method is implemented in a field programmable gate array chip. The provided simulations and experimental results validate the proposed method. [ABSTRACT FROM AUTHOR]

With the increasing demand for free-space/underwater environmental monitoring, disaster precaution, and manufacturing industry applications, free-space optical (FSO)-plastic optical fiber (POF)-underwater wireless optical communication (UWOC) convergence is designed to be a promising framework for providing long-haul free-space with underwater links. An 82-m 9 Gb/s four-level pulse amplitude modulation (PAM4) FSO-POF-UWOC convergent system employing a 405-nm blue-light injection-locked laser diode (LD) is thereby offered and practically demonstrated. Results reveal that a 1.8-GHz 405-nm blue-light injection-locked LD can be effectively applied for a 9-Gb/s PAM4 signal transmission over 50-m FSO link, 30-m graded-index (GI)-POF transportation, and 2 m clear ocean underwater channel. To the authors’ understanding, this study is the first to practically build an 82-m 9 Gb/s PAM4 FSO-POF-UWOC convergent system that effectively constructs a long-haul optical wireless-wired-wireless link using doublet lenses, GI-POF, and optical beam reducer. The performances of the proposed convergent systems are analyzed by bit error rate and non-return-to-zero eye diagram in real-time over an 82-m transport. This framework is the leading one to establish a long-haul FSO-POF-UWOC convergent system with qualified transmission performances. It guides a promising way to facilitate wide applications in the convergence of FSO, POF, and UWOC. [ABSTRACT FROM AUTHOR]

A high-speed 84 Gb/s vestigial sideband (VSB)–eight-level pulse amplitude modulation (PAM8) fiber-invisible laser light communication (IVLLC) integration based on vertical-cavity surface-emitting laser (VCSEL) transmitter with injection locking scheme is proposed. To the authors’ knowledge, this study is the first to realize a high-speed 84 Gb/s VSB-PAM8 VCSEL transmitter-based fiber–IVLLC integration. It is effectual to adopt an optical VSB-PAM8 signal in fiber–IVLLC integrations to suppress the linewidth of an optical signal so as to reduce the fiber dispersion. An injection locking scheme and a linear equalizer possess enhancements in frequency response, and thereby provide good transmission performances in a high-speed VSB-PAM8 fiber–IVLLC integration. Impressive bit error rate performance and clear eye diagrams are acquired in real time at a 25-km single-mode fiber operation with a 10-m free-space link. Such proposed 84 Gb/s VSB-PAM8 VCSEL transmitter-based fiber–IVLLC integration is a notable option for providing high transmission rates at optical fiber and optical wireless communications. [ABSTRACT FROM AUTHOR]

A high-speed (400 Gb/s) and long-reach (180 m) four-level pulse amplitude modulation (PAM4) optical wireless communication system employing Mach–Zehnder modulator (MZM)-optoelectronic oscillator (OEO) broadband light source (BLS) and doublet lenses is proposed. Analytic results show that the data rate is markedly improved by PAM4 modulation and MZM-OEO BLS with multiple wavelengths, and the free-space transmission distance is considerably increased by a couple of doublet lenses. With the support of PAM4 modulation, MZM-OEO BLS, and doublet lenses, good bit error rate performance and clear PAM4/nonreturn-to-zero eye diagram are achieved at a 400 Gb/s/180 m operation. The proposed system is presented to be an eminent one not only as a result of its evolution in free-space optical (FSO) links, but also on account of its high-speed and long-reach characteristics in FSO links. [ABSTRACT FROM AUTHOR]

A 103.12-Gb/s wavelength-division-multiplexing (WDM) four-level pulse amplitude modulation (PAM4) transmission based on 850-nm and 880-nm vertical-cavity surface-emitting lasers (VCSELs) with light injection and optoelectronic feedback techniques is proposed and experimentally demonstrated. Results show that two such 7.5-GHz VCSELs with light injection and optoelectronic feedback techniques are potent for 103.12-Gb/s WDM PAM4 transmissions. To the authors’ knowledge, it is the first one to successfully adopt two VCSEL transmitters with light injection and optoelectronic feedback techniques in a WDM PAM4 transmission. A total transmission rate of 103.12 Gb/s (51.56 Gb/s/λ × 2 λs) is achieved in the proposed WDM PAM4 transmissions. The link performances of the proposed WDM PAM4 transmissions have been evaluated in real time. Good real-time bit error rate performance and three independent clear eye diagrams are obtained at a 180-m OM4 multimode fiber operation. Such a proposed 103.12-Gb/s WDM PAM4 VCSEL-based transmission has great potential for providing efficient bandwidth in short-reach optical communications. [ABSTRACT FROM PUBLISHER]

A 56 Gb/s four-level pulse amplitude modulation (PAM4) light-based WiFi (LiFi) transmission based on a 680-nm/5.4-GHz vertical-cavity surface-emitting laser (VCSEL) with a two-stage injection-locked technique is proposed and demonstrated. Experimentally results show that a 5.4-GHz VCSEL with a two-stage injection-locked technique is effective for 56 Gb/s PAM4 LiFi transmissions. To the authors’ knowledge, it is the first one to adopt a 680-nm VCSEL transmitter with two-stage injection-locked technique in a 56 Gb/s PAM4 LiFi transmission. A pair of doublet lenses is employed in the proposed PAM4 VCSEL-based LiFi transmissions to enhance the free-space link. The link performances of the proposed PAM4 LiFi transmissions have been analyzed in real time. Good bit error rate performance and three independent clear eye diagrams are obtained over a 20-m free-space link. Such a proposed 56 Gb/s PAM4 VCSEL-based LiFi transmission with two-stage injection-locked technique has the potential to play a significant role in future wireless infrastructure for providing high transmission rate and long free-space transmission distance effectively. [ABSTRACT FROM PUBLISHER]

This paper proposes and presents the experimental demonstration of 320-Gb/s free-space optical (FSO) communication based on dense-wavelength-division-multiplexing (DWDM) technology and afocal scheme. To the best of our knowledge, this is the first one that adopts DWDM technology and afocal scheme to successfully demonstrate 50-m/320-Gb/s FSO communication. Results show that the free-space transmission distance is greatly increased by the afocal scheme and that the free-space transmission rate is significantly enhanced by the DWDM technology. DWDM FSO communication over a 50-m free-space link with a total transmission rate of 320 Gb/s (40\;\textGb/s/\lambda \times 8\lambda=320\;\textGb/s) is achieved. With the aid of a low-noise amplifier and clock/data recovery at the receiving site, good bit-error-rate (BER) performance and clear eye diagram are obtained at a 50-m/320-Gb/s operation. Such 50-m/320-Gb/s DWDM FSO communication provides the advantages of optical wireless communications for long transmission distance and high transmission rate, which is thoroughly useful for long-haul and high-speed light-based WiFi (LiFi) applications. [ABSTRACT FROM PUBLISHER]

An innovative free-space optical (FSO) link using laser light propagation to achieve transmission rate of 40 Gb/s at a wavelength of 1550 nm is proposed and experimentally demonstrated. Over a 20-m free-space link, brilliant bit-error-rate performance and clear eye diagram are obtained in the proposed 1550-nm distributed feedback (DFB) laser diode (LD)-based FSO links. As far as we know, it is the first time that a 1550-nm externally modulated laser transmitter cascaded with an erbium-doped fiber amplifier and a pair of fiber collimators to successfully set up a 20-m/40-Gb/s FSO link has been employed. Compared with the 680-nm vertical-cavity surface-emitting laser-based FSO link, this proposed 1550-nm DFB LD-based FSO link is attractive not only because it has longer free-space transmission distance but because it supplies higher bandwidth operation as well. Such a 1550-nm DFB LD-based FSO link provides the benefits of optical wireless communications for longer transmission distance and higher transmission rate, which is thoroughly helpful for optical wireless network applications. [ABSTRACT FROM PUBLISHER]

A progressive bidirectional cable television (CATV)/wireless-over-fiber lightwave transmission system based on one broadband light source (BLS), one arrayed waveguide grating, two intensity modulators, and one phase modulator is proposed and experimentally demonstrated. A continuous amplified spontaneous emission BLS is split into eight channels in the C-band with 50-GHz spacing. The multiple equal-space optical spectra exhibit a high optical signal-to-noise ratio (≥ 55 dB) and good flatness (≤ 5 dB). A high-quality comb multicarrier provides a single wavelength and twin millimeter-wave bands for baseband CATV and wireless transport systems. Several measured values (carrier-to-noise ratio ≥ 64 dB, composite second order ≥ 62 dB, composite triple beat ≥ 63 dB, and bit error rate \leq 10^-9 ) can be obtained from distortion-reduced and noise-free performance. Moreover, downstream and upstream high-bit-rate wireless transmissions exhibit an interference-eliminating property. Thus, the proposed system does not only offer a future for progressive fiber backbone and CATV/wireless hybrid networks, but also provides a full-duplex interference-free for high-data-rate mobile communication and in-home CATV access networks as well. [ABSTRACT FROM PUBLISHER]

This letter proposes and experimentally demonstrates a hybrid cable television (CATV)/16-quadrature amplitude modulation (QAM)-orthogonal frequency-division multiplexing (OFDM) in-house network over a combined 40 km single-mode fiber, 1.43 km photonic crystal fiber, and 30 m graded index-plastic optical fiber/5 m visible light communication transport. Good performances of carrier-to-noise ratio, composite second-order, and composite triple-beat are obtained for the CATV signal. A low bit error rate value is achieved for the 16-QAM-OFDM signal. [ABSTRACT FROM PUBLISHER]

In this brief, a digital-control adaptive phase-locked loop (PLL) with a digital locking-in monitor (LIM) consisting of a time-to-digital converter (TDC) and a bandwidth control unit (BCU) is proposed to reduce the locking time as well as to suppress the jitter when locked. It uses a delay-independent threshold in a dual-slope transfer function to detect the locked state according to the counting result of the proposed TDC, which feeds to the BCU to switch the bandwidth of PLL. Then the PLL is switched from a wide loop bandwidth (6 MHz) to a narrow bandwidth (3 MHz) in the locked state. To verify the proposed scheme, the proposed adaptive PLL is implemented in a TSMC 0.18 \mum 1P6M CMOS process with a supply voltage of 1.8 V. The measurement results show that the locking time is reduced by 67% while with a RMS jitter of only 8.79 ps when operating at 1.6 GHz. [ABSTRACT FROM AUTHOR]

We present a new reseeding-mixing method to extend the system period length and to enhance the statistical properties of a chaos-based logistic map pseudo random number generator (PRNG). The reseeding method removes the short periods of the digitized logistic map and the mixing method extends the system period length to 2^253 by “xoring” with a DX generator. When implemented in the TSMC 0.18-\mu\ m 1P6M CMOS process, the new reseeding-mixing PRNG (RM-PRNG) attains the best throughput rate of 6.4 Gb/s compared with other nonlinear PRNGs. In addition, the generated random sequences pass the NIST SP 800-22 statistical tests including ratio test and U-value test. [ABSTRACT FROM PUBLISHER]

A fiber optical CATV transport system that employed an upconverted technique and a phase modulation scheme to reduce noise and distortion induced by system is proposed and experimentally demonstrated. In contrast to a fiber optical CATV transport system that used a conventional intensity modulation scheme, excellent performances of carrier-to-noise ratio, composite second order, and composite triple beat are obtained in our proposed systems over a 100-km single-mode fiber transmission. It verifies the feasibility of the proposed systems and reveals an outstanding one with excellent transmission performances. [ABSTRACT FROM PUBLISHER]

In this brief, by operating the shifting and addition in parallel, an error-compensated adder-tree (ECAT) is proposed to deal with the truncation errors and to achieve low-error and high-throughput discrete cosine transform (DCT) design. Instead of the 12 bits used in previous works, 9-bit distributed arithmetic-precision is chosen for this work so as to meet peak-signal-to-noise-ratio (PSNR) requirements. Thus, an area-efficient DCT core is implemented to achieve 1 Gpels/s throughput rate with gate counts of 22.2 K for the PSNR requirements outlined in the previous works. [ABSTRACT FROM PUBLISHER]

A bidirectional wavelength-division-multiplexing (WDM) transport system base on two reflective semiconductor optical amplifiers (RSOAs) and optoelectronic feedback technique is proposed and experimentally demonstrated. One RSOA is employed as a broadband light source and another RSOA in combination with optoelectronic feedback technique is used as wavelengths reuse and data signal remodulation scheme. System architecture is further simplified by using only one RSOA at the optical node, and system performance is further improved by optoelectronic feedback technique. Impressive performances of bit error rate (BER) (<10^-9) were achieved for both 2.5 Gbps down-link and 1.25 Gbps up-link transmissions. [ABSTRACT FROM PUBLISHER]