Rick C. J. Hsu

Coherent optical MIMO (COMIMO)

We present a multiple-input multiple-output (MIMO) optical link based on coherent optics and its ability to exploit the inherent information capacity of multimode fiber. A coherent implementation differs from previous work in optical MIMO by allowing the system to tolerate smaller modal delay spreads, because of a much larger carrier frequency, and yet maintain the necessary diversity needed for MIMO operation. Furthermore, we demonstrate the use of MIMO adaptive equalization to mitigate intersymbol interference when exceeding the bandwidth-length product of the link. The impact of phase noise is studied with numerical simulation.

Fundamentals and challenges of optical multiple-input multiple-output multimode fiber links [Topics in Optical Communications]

In this article we discuss the application of MIMO processing to multimode fiber links. MIMO processing is shown to increase the information capacity of communication links linearly as the minimum number of transmitters/receivers increases. The fundamentals of optical MIMO fiber links are presented, and the promises and challenges of such systems are elaborated

Capacity enhancement in coherent optical MIMO (COMIMO) multimode fiber links

In this paper, we study a coherent optical MIMO (COMIEMO) multi-mode fiber link proposed for enhancing the fiber information capacity. We examine the statistical characterization of the equivalent MIMO channel and the improvement in the fiber capacity due to MIMO transmission. It is shown that the equivalent channel behaves similarly to a complex Gaussian MIMO channel, suggesting that the available results on wireless MIMO communication systems can be applied to optical fiber links for capacity enhancement.

Coherent optical MIMO (Invited Paper)

In this paper we present a Coherent Optical Multiple-Input Multiple-Output (COMIMO) communication system and its ability to exploit the inherent information capacity of Multi-Mode Fiber (MMF). COMIMO technique is a promising approach to unlock the information capacity of MMF as it ensures the necessary diversity for practically any fiber length. When exceeding the bandwidth-length product of the link, MIMO adaptive equalization can be used to mitigate inter-symbol interference (ISI). Furthermore, COMIMO link provides additional security in the physical layer that complements encryption.

Digital adaptive phase noise reduction in coherent optical links

Coherent optical links enable high-density constellations and, consequently, a higher throughput. However, the phase noise associated with the transmitter and the receiver lasers is a challenging issue in coherent lightwave systems. The authors present an approach that relies on using digital signal processing techniques to compensate for the laser phase-noise effects. The proposed approach exploits the digital processing power to address the problems arising from optical imperfections. The authors present an adaptive filtering scheme that reduces the effect of the laser phase noise and, consequently, relaxes the laser linewidth requirement. The proposed approach shows how the signal processing techniques can be exploited to compensate for the optical impairments by utilizing the continuing scale down in size and power in very large scale integration (VLSI) technology

All-dielectric photonic-assisted wireless receiver

High Power Microwave (HPM) weapons and other sources of intense microwave power pose a growing threat to modern RF receivers. To address this problem, all-dielectric photonic-assisted receivers have been proposed and demonstrated. Here, we describe a new configuration of this type with 15 dB better sensitivity over prior designs. The complete lack of metal and electronics in the front-end offers immunity against damage from intense electromagnetic radiation. In this experiment, detection of C band electromagnetic signal at 6.54 GHz with a sensitivity of -112 dBm/Hz is demonstrated.

All-Dielectric Photonic-Assisted Wireless Receiver

We describe a new configuration of an all- dielectric wireless receiver with 15 dB better sensitivity over prior designs. The complete lack of metal and electronics in the front-end offers immunity against damage from intense electromagnetic radiation.

Coherent optical multiple-input multiple-output communication over multimode fiber

It is shown that coherent optical implementation is crucial for an optical multiple-input multiple-output (MIMO) system to work. It ensures successful channel separation for practically any data rate or fiber length

ISI equalization for a coherent optical MIMO (COMIMO) system

We report the first demonstration of coherent optical MIMO utilizing adaptive equalization for ISI. Coherent optics implementation is essential to ensure the necessary diversity and hence MIMO benefits, independent of fiber length and data rate.