Graded-index Plastic Optical Fiber Research Articles

Various graded index plastic optical fiber performance signature capability with the optimum dispersion control for indoor coverage applications

Abstract This work has clarified the various graded index plastic optical fiber performance signature with the optimum dispersion control for indoor coverage applications. The plastic optical fibers that are deeply employed namely Polymethyl mathacrylate (PMMA), Epoxy, Polyfluorene and Cyclotene. Various plastic optical fiber dispersion is demonstrated against temperature variations. The different plastic fibers pulse broadening is clarified versus temperature variations. The previous plastic optical fibers types with respect to refractive index configuration and number of modes are clarified. Previous studies on PMMA/CYTOP plastic optical fibers attenuation is clarified against wavelength band variations. Various transmission techniques are applied to measure the fiber bandwidth and fiber channel bit rate. These transmission techniques are MTDM, NRZ and RZ coding. Different plastic fiber bandwidth against fiber channel distance is demonstrated based on NRZ, RZ and MTDM coding at room temperature. Different plastic fiber channel bit rate against fiber channel distance is studied and clarified based on NRZ, RZ and MTDM coding at room temperature. The choice of these plastic fibers are high temperature stability and more flexibility/reliability than other plastic fibers. The dispersion of these proposed plastic fibers can be controlled and managed with the control of temperature variations.

Mode group division multiplexing communication with the use of graded-index plastic optical fiber

Mode group division multiplexing communication with the use of graded-index plastic optical fiber

Theoretical Investigation of the Influence of Wavelength on the Bandwidth in Multimode W-Type Plastic Optical Fibers with Graded-Index Core Distribution.

The bandwidth of multimode W-type plastic optical fibers (POFs) with graded-index (GI) core distribution is investigated by solving the time-dependent power flow equation. The multimode W-type GI POF is designed from a multimode single-clad (SC) GI POF fiber upon modification of the cladding layer of the latter. Results show how the bandwidth in W-type GI POFs can be enhanced by increasing the wavelength for different widths of the intermediate layer and refractive indices of the outer cladding. These fibers are characterized according to their apparent efficiency to reduce modal dispersion and increase bandwidth.

Investigation of bandwidth in multimode graded-index plastic optical fibers.

A new method is proposed for investigating the bandwidth in multimode graded-index plastic optical fibers (GI POFs). By numerically solving the time-dependent power flow equation, bandwidth is reported for a varied launch conditions (radial offsets) of multimode GI POF. Our theoretical results are supported by the experimental results which show that bandwidth decreases with increasing radial offset. This decrease is more pronounced at short fiber lengths. At fiber length close to the coupling length Lc at which an equilibrium mode distribution (EMD) is achieved, this decrease becomes slower, indicating that mode coupling improves bandwidth at larger fiber lengths. With further increase of fiber length, bandwidth becomes nearly independent of the radial offset, indicating that a steady-state distribution (SSD) is achieved. Such a fiber characterization can be applied to optimize fiber performance in POF links.

Wavelength dependent transmission in W-type plastic optical fibers with graded index core distribution

This paper investigates the wavelength dependence of the equilibrium mode distribution (EMD) and steady state distribution (SSD) in W-type plastic optical fibers (POFs) with graded index (GI) core distribution for parametrically varied width of the fiber's intermediate optical layer and refractive index of the outer cladding. The numerical solution of the time-independent power flow equation is used to determine the transmission characteristics of the W-type GI POF. We demonstrated that the coupling length Lc required to achieve an EMD in W-type GI POF is shorter than the length determined experimentally for the original SC GI POF at 633 nm. We also demonstrated that as the wavelength increases, the EMD and steady-state distribution (SSD) are achieved at shorter W-type GI POF lengths. This is explained by the increase in leaky mode losses as wavelength increases. This makes it easier to tailor W-type GI POFs to a specific application at different wavelengths.

Error-free PAM-4 transmission by a high-speed plastic optical fiber without forward error correction.

This Letter reports, to the best of our knowledge, the first study in which error-free four-level pulse-amplitude modulation (PAM-4) transmission has been achieved using a graded-index plastic optical fiber (GI POF) without the use of forward error correction (FEC) techniques, at a high data rate (>50Gb/s), for short-reach applications (10 m). The GI POF that is developed has the characteristic microscopic heterogeneities in the fiber core material, which provide distinct mode coupling and significantly stabilize PAM-4 data transmission. The results of the study in this Letter indicate that the GI POF achieves highly stable PAM-4 transmission without the need for the current FEC techniques, which seriously increase the communication delay and power consumption of the transmission systems. Our GI POF material is paving the way for "material changes the system" approaches for achieving unprecedented optical interconnects in real time at a high speed and with low power consumption.

Power flow in multimode W-type plastic optical fibers with graded index core distribution

A method is proposed for investigation of transmission along a multimode W-type (doubly clad) plastic optical fiber (POF) with graded index (GI) distribution of the core. The multimode W-type GI POF is designed from a multimode singly clad (SC) GI POF fiber upon modification of the cladding layer of the latter. The transmission characteristics of such proposed W-type GI POF are determined from the numerical solution of the power flow equation. We have shown that coupling length Lc at which an equilibrium mode distribution (EMD) is achieved in W-type GI POF is shorter than this length experimentally determined for the original SC GI POF. This is a consequence of leaky mode losses which reduce the number of higher guided modes involved in the coupling process, thus reducing the length Lc. We have shown that the shorter the length Lc, the earlier the bandwidth switches from the functional dependence of 1/z to 1/z1/2. We found that bandwidth improves with thinner and shallower intermediate layers. Finally, the bandwidth of the W-type GI POF analyzed in this work is greater if compared to the bandwidth of the original SC GI POF.

Low-Noise Graded-Index Plastic Optical Fiber Achieved by Specific Copolymerization Process

Ultra-high-definition (UHD) technologies have recently received attention on account of their practical applications in consumer electronics. UHD devices require uncompressed video transmission at a data rate exceeding 100 Gb/s; thus, an optical fiber connection is essential. In consumer applications, optical fibers are very short. Moreover, their connections must permit variations in the fiber alignment, which accommodates rough handling by consumers. Under this condition, the transmitted signal quality is significantly degraded owing to noise and instabilities that strongly depend on the fiber alignment conditions in optical modules and connectors. Therefore, graded-index plastic optical fibers (GI POFs) are promising optical cables for consumer applications because of their flexibility, safety, and high bandwidth. Recently, the authors experimentally demonstrated that GI POFs can reduce interferometric noise, such as modal noise and multipath interference noise, in a multimode fiber link based on a vertical-cavity surface-emitting laser (VCSEL). This noise reduction effect results from strong mode coupling of GI POFs, which is closely related to microscopic heterogeneous structures of a core polymer matrix. In this paper, a control method of mode coupling using the copolymerization process for fiber core materials is proposed. The formation of composition fluctuations by copolymerization increases the mode coupling in the GI POF core. It thereby enables highly stable and robust data transmission with a large fiber misalignment tolerance in a VCSEL-based multimode fiber link. The proposed method for mode coupling control is expected to contribute to household optical communication systems in the upcoming UHD era.

Influence of mode coupling on three spatially multiplexed channels in multimode graded index plastic optical fibers

The influence of mode coupling on three-channel spatial division multiplexing capability in multimode graded index plastic optical fibers is investigated by solving the power flow equation. Our numerical results show that mode coupling significantly limits the fiber length at which the spatial division multiplexing can be realized with a minimal crosstalk between three neighbor spatial optical channels. Three spatial channels in the multimode graded index plastic optical fiber can be employed with a minimal crosstalk up to the fiber length of 3.5 m, which is about 12.5% of the coupling length (fiber length where equilibrium mode distribution is achieved). Such characterization of multimode graded index plastic optical fibers should be considered in designing an optical fiber transmission system for space division multiplexing, particularly for small office networking.

Investigation of Mode Coupling in Graded Index Plastic Optical Fibers Using the Langevin Equation

By employing the Langevin equation, we have examined a mode coupling in graded index plastic optical fiber. The numerical integration of the Langevin equation is based on the computer-simulated Langevin force. The solution matches the experimental data reported previously. We have shown that by solving the Langevin equation (stochastic differential equation) one can treat a mode coupling in graded index plastic optical fibers, which is result of fiber's intrinsic random perturbations.

Spatial division multiplexing in nine-core graded index plastic optical fibers

We propose a spatial division multiplexing in a new designed multimode multicore graded index plastic optical fiber with nine cores arranged in an octagonal array. The influence of mode coupling on two-channel spatial division multiplexing capability in each of nine cores is investigated by solving the power flow equation. Our numerical results show that mode coupling significantly limits the fiber length at which the spatial division multiplexing can be realized in each of nine cores with a minimal crosstalk between two neighbor spatial optical channels. Two spatial channels in the proposed nine-core graded index plastic optical fiber can be employed with a minimal crosstalk up to the fiber length of 5 m, which is about 18% of the coupling length (fiber length where equilibrium mode distribution is achieved). Such characterization of multicore graded index plastic optical fibers should be considered in designing a multicore optical fiber transmission system for space division multiplexing.

Noise and Distortion Reduction in OFDM Radio-Over-Fiber Link by Graded-Index Plastic Optical Fiber

We demonstrate that a graded-index plastic optical fiber (GI POF) enables higher-quality radio-over-fiber (RoF) transmission of an orthogonal frequency-division multiplexing (OFDM) signal, compared with a conventional multimode fiber, for short-distance household applications (< 100 m). It is shown that the improvement in OFDM signal transmission, using the GI POF, can be attributed to the reduction in noise and intermodulation distortion, owing to the external optical feedback from the transmission fibers. The low noise and low distortion in the signal transmission are mainly due to the strong mode coupling in the GI POF, which is closely related to the microscopic heterogeneous structures in core polymer materials. The developed GI POF will be invaluable for RoF networks in households as a solution for indoor broadband wireless communications in the upcoming 5G era.

Low-noise radio over graded-index plastic optical fiber.

We developed a graded-index plastic optical fiber (GI POF) that enables lower-noise radio frequency (RF) transmission than conventional multimode fibers for short-distance household applications (<100m). It is shown that reflection noise degrades RF transmission, regardless of the carrier frequency, through the spurious generation that accompanies the RF modulation of a vertical-cavity surface-emitting laser. The GI POF with distinctive mode coupling, which is closely related to its microscopic polymer structure, suppresses noise and spurious generation to improve transmission quality. Our low-noise radio-over-GI-POF technology will offer significant advantages for optical wiring systems for broadcast and communication in small- and medium-scale buildings.

Power Flow in Graded-Index Plastic Optical Fibers

A method is proposed for predicting the evolution of the power distribution along graded-index plastic optical fibers. This method is verified against our recently reported measurements. The strong influence of mode coupling on the power distribution is demonstrated on a specific graded-index plastic fiber to illustrate the influence of mode coupling in applications, such as data transmission, power delivery, and sensing systems.

Nonlinear Distortion Reduction Effect of Graded-Index Plastic Optical Fiber

We experimentally demonstrate that a graded-index plastic optical fiber (GI POF) can significantly reduce transmitted signal distortion caused by the nonlinear response of a multimode fiber (MMF) link based on a vertical-cavity surface-emitting laser (VCSEL). The low distortion of the signal transmission is attributed to the strong mode coupling in the GI POF, which suppresses the increment in signal distortion due to the external optical feedback, by reducing the self-coupling of problematic back-reflected light into the VCSEL cavity. The strong mode coupling is closely associated with polymer-specific microscopic heterogeneous structures in the fiber core materials, suggesting that the signal distortion can be further reduced by controlling the microscopic properties. The nonlinear distortion reduction effect of our developed GI POF will be invaluable for next-generation MMF links based on multilevel modulation in the ultrahigh-definition era.

Unconventional plastic optical fiber design for very short multimode fiber link.

We introduce a graded-index plastic optical fiber (GI POF) design for very short-distance household applications, in which the transmission quality is predominantly determined by system noise rather than the loss and bandwidth. The developed GI POF has strong mode coupling with low accompanying scattering loss, which is closely related to the specific microscopic heterogeneities in the core material. Such characteristic mode coupling significantly decreases reflection noise, improving the transmission quality compared with silica GI multimode fiber (MMF) for lengths below 30 m. Moreover, in the GI POF link, the transmission quality tends to improve with increasing fiber length, despite the increased loss and decreased bandwidth. This feature suggests that the system noise can be controlled by the microscopic heterogeneous properties of the GI POF for a very short MMF link, where the fiber loss and bandwidth are sufficiently low and high, respectively. This unconventional concept for optical-fiber design can advance fiber-optic communication in emerging applications in households located near optical network terminals.

A 10-Meter Active Optical Cable Utilizing POF With 4 × 10-Gb/s CMOS Transceiver Chipsets

This paper presents a 10-m active optical cable (AOC) utilizing a graded-index plastic optical fiber (POF) for HDMI applications, where 4-channel 10-Gb/s/ch transceiver chipsets were implemented in 0.13-μm CMOS process and integrated upon a FR4 PC-board within pluggable connectors. Passive optical alignment comprising optical devices, optical subassembly, and POF was precisely located within the tolerance range of +/-10 μm, leading to successful mass-production. The transmitter (Tx) includes a VCSEL driver exploiting equalization and feedforward pre-emphasis to support 10-Gb/s data modulation. Also, a novel input data detector is proposed to turn on/off VCSEL diodes automatically for longer sustainability and lower power consumption. The receiver (Rx) employs a double-gain feedforward transimpedance amplifier followed by a selectable two-stage equalizer to choose either 6-Gb/s or 10-Gb/s operations, depending upon the specified HDMI applications. Also, a simple dc offset current cancellation and a novel monitor circuit are proposed for stable biasing and to keep tracking the average photocurrent of each photodiode. Measured results of Tx demonstrate 5.6-mA bias currents and 6.0-mAPP modulation currents, consuming 21.25 mA in maximum, whereas Rx provides 56.7-dBΩ transimpedance gain, 6-GHz bandwidth, and -10.4-dBm optical sensitivity for 10 -12 BER with 21.2 mA current consumption. The 10-meter POF AOC demonstrates wide and clean eye-diagrams up to 10 Gb/s, successfully showing 8-Mpixel 60-fps video data stream.

Intrinsically Stabilized Plastic Optical Fiber Link Subject to External Optical Feedback

We develop a graded-index plastic optical fiber (GI POF) that can significantly stabilize a multimode fiber (MMF) link with a vertical-cavity surface-emitting laser (VCSEL) subject to external optical feedback. It is demonstrated that the dominant mechanism for this stabilization effect is the strong mode coupling of the GI POF, which is closely related to the polymer-specific microscopic heterogeneities in the GI POF core material. Such mode coupling decreases correlation between the problematic reflected light field and VCSEL cavity field, increasing tolerance of the MMF link for external optical feedback. Our developed GI POF with specific microscopic heterogeneities prevents the external-optical-feedback-induced critical destabilization observed for silica GI MMFs. These results suggest that the stabilization effect can be controlled by microscopic properties regardless of the fiber attenuations and core refractive indices.

Phase-Modulated Hybrid High-Speed Internet/WiFi/Pre-5G In-Building Networks Over SMF and PCF With GI-POF/IVLLC Transport

To the best of our knowledge, a phase-modulated hybrid high-speed Internet/wireless local area network (WLAN) wireless fidelity (Wi-Fi)/pre-fifth-generation (Pre-5G) in-building network over an integration of single-mode fiber (SMF), phonic crystal fiber (PCF), and graded index-plastic optical fiber (GI-POF)/invisible laser light communication (IVLLC) transmission is feasibly demonstrated for the first time. An effective fiber Bragg grating (FBG)-based phase modulation (PM)-to-intensity modulation (IM) conversion scheme is adopted to replace the sophisticated dispersion-induced PM-to-IM conversion scheme or costly delay interferometer (DI). This proposal is the first one to deliver high-speed Internet, WLAN Wi-Fi, and Pre-5G broadband heterogeneous services so as to bridge fiber backhaul and in-building network. The light is phase-modulated with 4-Gb/s four-level pulse amplitude modulation (PAM4) (high-speed Internet), 24-Mbps/2.4-GHz microwave (MW) (WLAN Wi-Fi), and 5-Gb/s/3.5-GHz 16-quadrature amplitude modulation-orthogonal frequency-division multiplexing (Pre-5G) data signals over 41.44-km fiber link (40-km single-mode fiber +1.44-km photonic crystal fiber) with 30-m GI-POF/IVLLC transmission. Bit error rate, PAM4 eye diagrams, error vector magnitude, and constellation map are examined to perform well to reveal the practicality of constructing a phase-modulated hybrid high-speed Internet/Wi-Fi/Pre-5G in-building network.

Low-Noise Graded-Index Plastic Optical Fiber for Significantly Stable and Robust Data Transmission

Internet traffic continues to grow with the increase of network-connected smartphones, tablets, televisions, and monitoring devices in the Internet-of-Things (IoT) era. This trend will be significantly accelerated by the introduction of ultrahigh-definition (UHD) imaging technologies in various applications, and existing optical networks including datacenter networks are under urgent development to accommodate this traffic. However, optical fibers have not been introduced into households located in optical network terminal areas, even though UHD device connections require decompressed high-volume data transmission at more than 100 Gb/s, where a multilevel modulation scheme is vital. In UHD applications, very short optical cables (typically less than several meters) are connected and disconnected by consumers in a manner similar to metal interface cables. Under such conditions, a data transmission quality is predominantly limited by noise and instability rather than bandwidth and loss. Here, we propose low-noise graded-index plastic optical fibers (GI POFs) that enable significantly stable and robust data transmission through strong mode coupling, whose mechanism is fundamentally different from that of silica optical fibers. The low-noise GI POF link eliminates the need for the precise fiber alignment, angled fiber facets, and optical isolators typically used in conventional links. Our proposed GI POF material paves the way for quick optical fiber connections for multilevel UHD video transmission, becoming the first “capillaries of light” from optical network terminals in the IoT era.