Flexible Multimode Polymer Waveguide Arrays for Versatile High-Speed Short-Reach Communication Links

Abstract

Optical interconnects play an important role in enabling high-speed short-reach communication links within nextgeneration high-performance electronic systems. Multimode polymer waveguides in particular allow the formation of high-capacity optical backplanes and cost-effective board-level optical interconnects. Their formation on flexible substrates offers significant practical advantages and enables their deployment in environments where shape and weight conformity become particularly important, such as in cars and aircraft. However, bending and twisting of flexible multimode waveguides can have a significant effect on their optical transmission performance due to mode loss and mode coupling. Moreover, the magnitude of the induced effects strongly depends on the launch conditions employed. In this paper, therefore, we present detailed loss, crosstalk, and bandwidth studies on flexible multimode waveguide arrays for different launch conditions regarding their use in real-world systems. The minimum radius to achieve a 1 dB excess bending loss is obtained for each launch condition as well as the crosstalk degradation due to bending. It is shown that for a 50 µm MMF input, a 6 mm bending radius is required for excess losses below 1 dB, while crosstalk below −35 dB is obtained in adjacent waveguides even under strong bending. Moreover, it is found that twisting has a small effect on the loss and crosstalk performance of the samples. Excess twisting loss less than 0.1 dB and crosstalk of −40 dB are obtained for three full 360°turns under a 50 µm MMF launch. Finally, the bandwidth studies carried out on the samples indicate than no significant bandwidth degradation is induced due to sample bending, with bandwidth-length product values larger than 150 GHz × m obtained for restricted launches. The set of results presented herein specify the deployment of this flexible polymer multimode waveguide technology in real-world systems and demonstrate its strong potential to implement low-loss highbandwidth optical interconnects.

Progress in wearable electronics/photonics—Moving toward the era of artificial intelligence and internet of things

“…The optimal coupling loss of −17 dB dominated by mode mismatch is reported together with a waveguide peak power of 11.8 μW. Other than sensing, another critical application of wearable photonics is high‐speed data transmission 14,179 . Figure 5E shows a recent advance of flexible photonics for high‐speed data transmission applications 23 .…”

“…On the one hand, by using the optical sensing path, the wearable photonic sensors are invulnerable to EMI 15,157 . On the other hand, the photonic interconnects can easily achieve GHz data transmission rate that enables real‐time monitoring and feedback 14,23,158 . Furthermore, the mid‐infrared (MIR) photonic sensors are miniaturized devices with selective, label‐free, and damage‐free sensing capability 159‐161 .…”

“…In this regard, wearable electronics are able to achieve the same functionalities more conveniently and thereby improve the interaction experience between humans and devices. Except for the general wearable electronics, wearable photonics involving optical communication path can be a good complement and bring extra advantages in the whole wearable systems, such as ultra‐fast data transmission and high reliability with electromagnetic interference (EMI)‐free 14,15 . Since appearance, wearable electronics and photonics have shown great impacts on our lifestyle, benefiting broad applications including electronic‐skin (E‐skin), 16 healthcare (eg, physical and psychological) monitoring and treatment (eg, drug delivery), 17,18 environmental monitoring and intervention, 19 flexible displays, 20 soft robotics, 21 prosthetics, 22 ultra‐fast data communication, 23 human‐machine interactions, 24 and so on.…”

Polymer-Based Microring Resonator with the Multimode Interference Coupler Operating at Very-Near-Infrared Wavelengths

“…Microring resonators have been demonstrated on different optical materials such as silicon-on-insulator (SOI) [11], Si x N y [12,13], and polymers [14][15][16]. Compared with conventional inorganic materials, polymers as organic materials have advantages such as low cost, high optical transmittance, and simple fabrication processes [17,18]. Moreover, different unique properties such as low loss and high electro-optic coefficient can be achieved by operating on molecular scale during 2 of 9 chemical synthesis [19,20].…”

Ultra-Low Cost High-Density Two-Dimensional Visible-Light Optical Interconnects

“…High-speed free-space and POFbased optical links have been demonstrated achieving data rates ≥ 5 Gb/s using a single µLED [8,28,31], while schemes employing multiple transmitters, such as optically-generated pulse amplitude modulation (PAM) schemes [32], multiple input multiple output (MIMO) systems [6] and coarse wavelength multiplexing have also been demonstrated using µLED arrays [15,33]. In addition, siloxane-based materials have been shown to exhibit high temperature resistivity in excess of 300°C and long lifetimes, while large multimode polymer waveguide arrays exhibiting low loss and low crosstalk have been cost-effectively integrated onto PCBs [34,35] and flexible substrates [36,37].…”