KEYWORDS: Polymer optical fibers, Phase only filters, Connectors, Signal to noise ratio, Modulation, Data transmission, Data communications, Tolerancing, Silica, Signal attenuation
The recent deployment of ultra-high definition (UHD) applications rapidly increases data traffic in communication networks including datacenter networks. In datacenters, a large number of parallel optical links with multi-fiber push-on (MPO) connectors are employed for high-speed inter-switch communications. However, it needs precise alignment to completely eliminate air gaps in MPO connectors, and the air gaps increase noise owing to optical reflection. Here, we demonstrate that graded-index plastic optical fibers (GI POFs) increase tolerance to the connector reflection for high-quality data transmission because of its intrinsic mode coupling. This feature of the GI POFs will be advantageous to MPO-connector-based interconnect for data center applications in the upcoming UHD era.
Ultra-high-definition applications will be one of the main drivers for emerging 5G communications. 5G supports higher data rate utilizing higher frequency bands than those in existing cellular systems. However, higher-frequency radio waves have higher directionalities, resulting in decreased indoor coverage. Therefore, radio-over-fiber (RoF) systems are needed for indoor distribution of wireless signals. Recently, we developed a graded-index plastic optical fiber (GI POF) that enables higher-quality RoF transmission than conventional multimode fibers for short-distance links (<100 m). The GI POF can reduce noise and distortion in RoF transmission through its strong mode coupling. Here, we demonstrate that the GI POF significantly increases fiber-misalignment tolerance in RoF transmission. The GI POF will realize do-it-yourself optical fiber connections for indoor applications.
The growing demand for high-speed data transmission in consumer applications such as 4K/8K television motivates the development of multilevel modulation. Multilevel modulation can increase bit rate over 2-level modulation for same symbol rate, but is subject to noise and modulation instability in optical link. Recently, we experimentally demonstrated that a graded-index plastic optical fiber (GI POF) significantly improved the transmission signal quality compared with a silica GI multimode fiber (MMF) in the consumer-friendly MMF link without an optical isolator, where laser and optical fiber easily coupled. This high-quality transmission is related to reflection noise reduction because of a strong mode coupling in the GI POF. However, the signal quality also depends on the modulation response of the vertical-cavity surface-emitting laser (VCSEL) coupled with optical fibers. Here, we investigate the influence of the strong mode coupling in the low-noise GI POF on the modulation response of the VCSEL in the consumer-friendly MMF link. We show that the low-noise GI POF can significantly decrease the distortion of the modulation response compared with the silica GI MMF which easily coupled with the VCSEL. This low-distortion performance is related to the strong mode coupling in the low-noise GI POF, which stabilizes the VCSEL owing to the self-coupling reduction of the optical feedback into the VCSEL cavity. This suggests that the novel GI POF allows for highly-stabilized multilevel transmission for consumer-friendly 8K interface. In the conference, we will also discuss the mechanism for the stabilization effects of the low-noise GI POF using theoretical analyses.
A graded-index plastic optical fiber (GI POF) with a high bandwidth and flexibility is expected to be a transmission medium for short-reach communication in home networks. However, the pluggable interconnects for consumers have not been emerged. Recently, we have developed ballpoint-pen interconnects where ball lens can be precisely mounted on GI POF end face using ballpoint-pen production technology, enabling easy connection, low-cost production, and fiber end face protection of GI POFs. Here, data transmission quality through coupled GI POFs with the ballpoint-pen connector is investigated. For evaluating data transmission quality, we measured bit error rate versus received optical power (BER curve) for a connector separation of 1.5 mm in the ballpoint-pen interconnect. The result shows error-free transmission (BER<10-12) was achieved by using the ballpoint-pen interconnect whereas transmission quality was significantly deteriorated by using the butt-coupling which is generally physically-contacted without fiber separations. This achievement with the ballpoint-pen interconnect may result from little dependence of the coupling loss on the connector separation because of the collimated output beam from GI POF with the ballpoint-pen connector. Furthermore, even for same received optical powers in the BER curve, the butt-coupling has worse transmission quality than the ballpoint-pen interconnect. This may result from some noises such as modal noise which occurs in multimode fiber connection as fluctuations of the coupling power. These results suggest that the ballpoint-pen interconnect is suitable for a consumer applications where the pluggable interconnects are essential. In the conference, the connector separation dependence of transmission quality through ballpoint-pen interconnect will be discussed.
Conference Committee Involvement (5)
Ultra-High-Definition Imaging Systems V
21 February 2022 | San Francisco, California, United States
Ultra-High-Definition Imaging Systems IV
6 March 2021 | Online Only, California, United States
Ultra-High-Definition Imaging Systems III
3 February 2020 | San Francisco, California, United States
Ultra-High-Definition Imaging Systems II
2 February 2019 | San Francisco, California, United States
Ultra-High-Definition Imaging Systems
31 January 2018 | San Francisco, California, United States
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