The field of integrated photonics holds great promise for overcoming societal challenges in data and telecom, autonomous driving and healthcare in terms of cost, performance, and scalability. Similar to the semiconductor industry, the ever-increasing demands of various applications are driving the necessity for platform integration in photonics as well, enabling seamless integration of diverse functionalities into compact and efficient photonic devices. Indium Phosphide allows the monolithic integration of all required functionalities. This high level of integration reduces footprint and drives down system level costs.

Future short-reach optical fiber communication links for datacenter and optical access applications would require not only high data rate but also low power/complexity. In this work, by leveraging a home-designed LiNbO3 intensity modulator with high slope-efficiency, we experimentally investigate a low-complexity/power optical pulse amplitude modulation (PAM) link with 300Gb/s data rate excluding FEC overhead and the following detailed merits: (1) at the transmitter side, no digital signal processing or a high-resolution wideband DAC is required, while only CMOS-class driving voltages less than 1 volt is needed; (2) at the receiver side, no optical or electrical amplifier is needed. It is found that for C-band 600m transmission, a symbol-spaced decision-feedback equalizer (DFE) with 91 feedforward taps and 1 feedback taps is sufficient to achieve a BER lower than the threshold of a low-power practical FEC. With these features, we expect that the overall system has low power consumption. A bitrate-distance product of >180Gb/s*km in C-band is achieved experimentally.

This invited talk delves into the advantages of Coherent Passive Optical Networks (PONs) and the necessary technological advancements to fully exploit its revolutionary capabilities. The discussion encompasses vital components of coherent PON technology, including upstream burst coherence, multiplexing in time and frequency domains, and streamlined coherent optics for access networks. Moreover, the talk explores diverse use cases for Coherent PON, spanning from FTTH/FTTP deployments to mobile x-haul and aggregation connectivity scenarios. The ongoing efforts to establish comprehensive CPON specifications are also highlighted.

Here, we're pioneering a novel approach in photonics, targeting the development of ultra-low power communication systems and advanced sensing technologies. Central to our strategy is the implementation of a unique zig-zag structure, designed to achieve femtojoule (fJ) per bit communication efficiency. A key innovation in our approach is the integration of unidirectional coupling through on-chip isolation, seamlessly connecting a Transverse Coupled Cavity VCSEL (TCCVCSEL) to the modulator and then to a waveguide. This project has wide-ranging implications, extending beyond just creating new devices. It's geared towards establishing a robust III/V platform, serving as a cornerstone in the field of photonics and integrated circuit technology. Our work is poised to catalyze advancements in high-speed, low-power photonic systems, potentially setting new benchmarks in the industry.

High temperature operation characteristics and reliability of an ultra-small silicon photonics transceiver equipped with a quantum dot laser up to an ambient temperature of 105°C are reported. An ultra-small silicon photonics transceiver of 5 by 5 mm size, called IOCore, is integrated with an optical transceiver of 32Gbps (PCIeGen5.0) by 4 lanes. The combination of Fabry-Perot quantum dot laser and Mz modulator provides good transmit/receive characteristics at 32Gbps * 4 lanes at an ambient temperature of 105 degreesC. Reliability tests showed that the quantum dot laser was estimated to have a very high lifetime of 5.6fit when used at 105 degreesC. at 10 degreesC. IOCore can be applied to onboard optics for devices that are difficult to replace in case of failure, or to outdoor optical modules that require I-Temp. Some examples of module development are shown.

The talk will review amplifier technologies used for undersea transmission and important factors that shape technology solutions. Discussion will cover EDFA evolution, components, and basic amplifier architectures. Special attention will be given to amplifier technologies with the introduction of spatial division multiplexing (SDM) and to future trends.

High-performance systems are increasingly bottlenecked by the energy and communications costs of interconnecting numerous compute and memory resources. Integrated silicon photonics offer the opportunity of embedding optical connectivity that directly delivers high off-chip communication bandwidth densities with low power consumption. Our recent work has shown how integrated silicon photonics with comb-driven dense wavelength-division multiplexing can scale to realize Pb/s chip escape bandwidths with sub-picojoule/bit energy consumption. Beyond alleviating the bandwidth/energy bottlenecks, embedded photonics can enable new architectures that leverage the distance independence of optical transmission with flexible connectivity tailored to accelerate distributed ML applications.

This conference presentation was prepared for SPIE Photonics West, 2024.

We review recent advancements in the digital longitudinal monitoring (DLM) of fiber-optic links. DLM visualizes physical link parameters distributed along the entire length of the link at a coherent receiver, such as longitudinal optical power profiles, locations of loss anomalies, and amplifier gains. This monitoring technique facilitates optical path provisioning and fault detection without the need for dedicated hardware devices such as OTDR. DLM is formulated as an inverse problem of the Nonlinear Schrödinger Equation (NLSE), where distributed coefficients in the NLSE are reconstructed from the boundary conditions, namely transmitted and received signals. We will present DLM from its theoretical aspect to practical applications in optical networks.

This talk reviews the wideband optical amplified transmission system that employs periodically poled LiNbO3 (PPLN) parametric optical amplification for high-capacity scalable optical transport network. The achievable optical amplification bandwidth beyond 10 THz is promising to offset capacity crunch in today’s network in combination with space-division multiplexing transport technologies. Our recent wideband WDM transmission experiments are introduced using PPLN acting as both wideband inline amplifiers and wideband wavelength converters.

Bismuth-doped fibre amplifiers (BDFA) have been shown to have gain over very large bandwidths in the O-band. The total supported bandwidth range with sufficient gain is larger than C and L band combined (>9THz). Hence, high capacity short range links supported by BDFAs can have a capacity beyond that of the conventional band-multiplexed configuration with separate C and L amplification. In this presentation we review, recent work on high capacity transmission and chromatic dispersion compensation.

We review our recent experiment on the Terabit-class coherent optical communication using a photonics integrated circuit-based optical amplifier. The 25.6-Tb/s 16-channel wavelength-division multiplexed (WDM) transmission (over 81-km fiber) proved the potential of such on-chip amplification for future coherent applications.

Multi-layer optical networks are a prospective concept in the upcoming era of bandwidth-abundant optical networks that decouple the enormous spatial division multiplexing (SDM) layer from the wavelength division multiplexing layer. In this direction, we present an analysis of a generalized multi-band optical cross-connect (OXC) at the networking level. This OXC operates in two stages: firstly, it groups wavelengths to form wavebands, and secondly, it switches them as waveband paths. The findings demonstrate that waveband routing is a viable and cost-effective replacement for traditional wavelength routing in massive parallel optical networks.