1,721,178 research outputs found
Integrated silicon electro-optical modulators for data/telecom applications
No full textOngoing growth of cloud computing and streaming is creating significant challenges for interconnect systems in data centers and high performance computing systems mainly in terms of data-rate, power consumption, size and cost. Maturing silicon photonics (SiP) technology allowing mass production of integrated photonic devices at a competitive cost due to the utilization of existing CMOS infrastructure, and enabling high integration of optical devices such as modulators at the wafer scale is expected to be particularly competitive to service an emerging need for ex-tended reach high-speed data center interconnects. Tremendous efforts have been made in the past decade to maximize the speed and reduce the power consumption of SiP modulators. In this thesis, we are going to address some of the challenges of SiP modulators: Full suppression of crosstalk and bandwidth improvement in travel-ling wave modulators, as well as reduction of fabrication sensitivity of silicon ring resonator modulators. We also introduce lumped element meandered modulators with improved power consumption while maintaining high optical bandwidth. Furthermore, a novel vertical phase shifter structure based on epitaxially grown silicon layer stack is introduced, designed, fabricated and characterized. The proposed ver-tical phase shifter exhibits one of the highest reported modulation efficiencies among silicon depletion based modulators. Finally, we explore alternative modulation mechanisms which can be realized in SOI platform by integration of novel material. In particular, we investigate the electro-optic (Pockels) effect in nitride cladded strained silicon Mach-Zehnder interferometers, Franz-Keldysh effect in germanium tin grown on germanium virtual substrate for mid-infrared applications, as well as Moss-Burstein effect in graphene-silicon slot waveguide absorption modulators
Electro-optical Modulator based on carrier depletion or carrier accumulation in semiconductors with advanced electrode configuration
No full textHigh-speed photonically-enabled ADCs with neuromorphic opto-electronic signal processing
No full textOptical fiber links have become ubiquitous in data center transceivers as well as 5G back-haul interconnects due to the massive parallelization, high bandwidth and low latency enabled by optics. To meet the ever-growing performance requirements of fiber optical networks, high-speed data converters are being continuously improved. A big challenge lies in reaching high bandwidths and sampling rates on one hand while maintaining high signal-to-noise ratios and large effective number ofbits on the other. To expand the boundaries of the trade-off between speed and resolution, many advanced architectures have been explored, in particular photonically-enabled data processing, which allows high-speed data conversion with high resolution leveraging the low jitter of ultra-stable mode-locked lasers. Electronic based digital signal processing in high data rate transceivers also inherits the noise resulting from the finite ENOB of high bandwidth analog-to-digital converters and results in high power consumption. Current research is therefore focusing on photonic neuromorphic signal processing. In particular, opto-electronic hybrid systems appear to be a promising solution to balance scalability, power consumption and speed requirements
Resonantly assisted silicon photonics transceivers for medium-reach interconnects
No full textMobile data traffic is on a constant rise, with emerging 5G technologies having to service a broad range of applications that require high throughput, low latency, and high reliability communication. Fiber optic links, based on standard single mode fibers (SMF), are one of the main candidates for transporting data from 5G cell sites to central offices, and further to remote data centers. To reduce infrastructure costs, silicon photonics (SiP) presents itself as the technology of choice for the necessary electro-optical transceivers, with its low per-unit cost for high-volume production, owing to its large degree of compatibility with the well-established complementary metal oxide semiconductor (CMOS) fabrication. Moreover, low power, frequency selective resonantly assisted SiP devices ease the implementation of multi-channel, wavelength division multiplexed (WDM) transceiver systems that increase parallelization. Furthermore, to meet the growing demands for data throughput, flexible, robust modulation schemes that rely on inexpensive direct detection (DD) are of great interest. The single-sideband orthogonal frequency multiplexing (SSB-OFDM), with its high tolerance to dispersion-mediated signal distortion, flexibility in spectral loading, and high spectral efficiency fits well the stated requirements. In that context, we investigate the feasibility and performance of SSB-OFDM links that rely on SiP ring resonator assisted modulation, while carefully taking other typical link components (lasers and amplifiers) into consideration. On the receiver side, we study a SiP WDM receiver system based on optical add-drop multiplexers (OADM) that handles polarization scrambling present in SMF data links. In this work, we present, to the best of our knowledge, for the first time a detailed analytical model for the laser phase noise to intensity noise conversion in resonant ring modulator (RRM) assisted DD data transmission. To validate the model, we perform a set of SSB-OFDM transmission experiments using a SiP RRM assisted modulator. Moreover, we numerically model the same link, including all imperfections associated with individual link components, with the laser phase noise introduced at the link end through the derived analytical expressions. Excellent agreement of experimental and modeling results confirms the validity of our analytical model. Additionally, we study how the optimal biasing point of the RRMs depends on the laser source characteristics, as well as the influence of component nonlinearities on the SSB signal. Lastly, we present a high-speed 10-channel polarization-diverse SiP WDM receiver with a reduced number of OADMs per channel and balanced group delays for orthogonal polarization states and experimentally benchmark the performance of each of the receiver channels
A co-packaged optics platform combining resonantly assisted silicon photonics modulators with glass-molded micro-optics
No full textThe skyrocketing demand for cost-effective digital data transfer has driven optical transceiver technologies into a thriving multibillion-dollar industry, particularly for implementing intra-data center interconnects. This demand is further fueled by the growing interest in artificial intelligence, large language models, and other applications of machine learning. Due to the immense volume of data they handle, these applications often rely on server clusters, interconnected by fiber optic transceivers. Satisfying the requirements of this substantial market necessitates the development of large-scale integrated silicon photonics transceivers, capable of meeting strict specifications, including 100 Gbaud per fiber and wavelength. In this context, this thesis highlights the importance of power-efficient, high-bandwidth silicon electro-optic modulators, that convert electrical signals into the optical domain. The suggested modulators eliminate the need for active temperature stabilization through thermal tuning, resulting in reduced power consumption and enabling greater structural density, while simultaneously reducing energy usage and expenses for cooling, thereby reducing the environmental footprint. This is especially pertinent given the escalating global electric power consumption of the internet, currently accounting for approximately 5% of the total, with an anticipated upward trajectory. This concern is further magnified by the increasing urgency of the climate crisis, underscoring the need for more sustainable and energy efficient modes of communication. Despite these formidable challenges, the ongoing processes of digitization and automation contribute to a reduction in overall environmental impact compared to outdated data processing techniques. The transition toward digitalization, automated data processing, and remote work, facilitated by data centers and the internet, can be viewed as significant steps toward a world powered by renewable and responsible energy usage. In addition to transducers, lasers, often associated with energy inefficiency in optical links, can be optimized individually, a goal made achievable through the use of disaggregated laser sources. Efficient and scalable coupling of these sources to transducers is imperative. To address the complexities inherent in these challenges, this thesis additionally studies the development of power-efficient, cost-effective, and scalable coupling solutions. These innovations, combined with novel modulators, enable co-packaged optics, tailored specifically to the application for intra-data center interconnects. This thesis introduces a novel interposer configuration, primarily conceived within this work, and adapts the resonantly enhanced but broadband modulator concept from a different communication band, enhancing it across multiple performance dimensions. Furthermore, this work has resulted in the inception of the sub-wavelength tunneling barrier structure, leveraging metamaterials to mitigate bending losses in rib ring resonator modulators. To enable a photonic integrated demonstrator, an array of passive components is custom-designed, along with thin-film coatings for the coupling solution to also support polarization-insensitive or multiplexed applications
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