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Single bus architecture and results a, Schematic of a Kerr frequency comb-driven single bus cascaded resonator-based link. b, Measured normal-GVD comb spectrum with dash-dotted and dashed lines denoting −6 dBm and −10 dBm thresholds, respectively. c,d, BER waterfall curves for eight measured comb lines at 10 Gb s⁻¹ (c) and 16 Gb s⁻¹ (d). All lines achieve a directly measured BER better than 10⁻⁹ for both data rates without FEC.
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The growth of computing needs for artificial intelligence and machine learning is critically challenging data communications in today’s data-centre systems. Data movement, dominated by energy costs and limited ‘chip-escape’ bandwidth densities, is perhaps the singular factor determining the scalability of future systems. Using light to send informa...
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To increase the optical interconnect transmission capacity, different multiplexing technologies, including wavelength division multiplexing (WDM), polarization division multiplexing (PolDM) and mode division multiplexing (MDM), can be utilized. Among them, MDM is a promising technique in silicon photonics (SiPh) integrated optical interconnects sin...
Citations
... For many applications, such as pump rejection in quantum photonics [11], a flattop passband is not a critical feature and insertion loss is more important. Another limiting case where loss and passband shape provide a difficult trade-off is the applications where ultra-narrowband filters are needed, such as in RF photonics [12][13][14]. Here, the narrowest bandwidth also depends on the passband shape. ...
Emerging applications of photonic integrated circuits are calling for extremely narrowband and/or low-insertion-loss bandpass filters. Both properties are limited by cavity losses or intrinsic quality factors. However, the choice of inter-cavity and bus couplings establishes trade-offs between these two properties and the passband shape, which have been little explored. Using the widely used second-order resonant system as an example, we present new, to the best of our knowledge, classes of filter passband shapes that provide the lowest insertion loss and the narrowest bandwidth for a given loss Q. A normalized design and novel properties based on a temporal coupled-mode theory model are presented, including a design tool to apply these results. These results may benefit loss-sensitive filtering applications such as quantum-correlated photon pair sources and RF-photonic integrated circuits.
... By coupling multiple Si-MRMs with slightly different radii to a single bus waveguide [7], it will enable electro-optic (E-O) modulation at various wavelengths concurrently, thereby maximizing the bandwidth density of photonic integrated circuits (PICs). Several on-chip WDM systems using Si-MRM array based on reversed PN junctions have demonstrated largescale integration with aggregated bandwidth by leveraging the top-quality fabrication capability offered by silicon photonics foundries [8][9][10][11][12][13][14][15][16][17]. However, the E-O efficiency of Si-MRMs by commercial foundries is limited by the relatively weak plasma dispersion of silicon and the low capacitance density of reversed PN junctions as discussed in Ref. [18]. ...
In pursuit of energy-efficient optical interconnect, silicon microring modulator (Si-MRM) has emerged as a pivotal device offering an ultra-compact footprint and capability of on-chip wavelength division multiplexing (WDM). This paper presents a 1 × 4 metal-oxide-semiconductor capacitor (MOSCAP) Si-MRM array gated by high-mobility titanium-doped indium oxide (ITiO), which was fabricated by combining Intel's high-volume manufacturing process and the transparent conductive oxide (TCO) patterning with the university facility. The 1 × 4 Si-MRM array exhibits a high electro-optic (E-O) efficiency with Vπ⋅L of 0.12 V⋅cm and achieves a modulation rate of (3×25 + 1×15) Gb/s with a measured bandwidth of 14 GHz. Additionally, it can perform on-chip WDM modulation at four equally spaced wavelengths without using thermal heaters. The process compatibility between silicon photonics and TCO materials is verified by such industry-university co-fabrication for the MOSCAP Si-MRM array and demonstrated enhanced performance from heterogeneous integration.
... The manipulation and control of light using photonic integrated circuits has enabled transformative advances in classical [1,2] and quantum computation [3,4], communications [5,6], and imaging [7][8][9]. In these on-chip optical systems, optical nonreciprocity is an essential tool that permits us to control the direction of light flow, protecting lasers and other optical components from the destabilizing effects of backscattered light. ...
Optical nonreciprocity plays a key role in almost every optical system, directing light flow and protecting optical components from backscattered light. Controllable forms of on-chip nonreciprocity are needed for the robust operation of increasingly sophisticated photonic integrated circuits (PICs) in the context of classical and quantum computation, networking, communications, and sensing. However, it has been challenging to achieve wideband, low-loss optical nonreciprocity on-chip. In this paper, we demonstrate strong coupling and Rabi-like energy exchange between photonic bands, possessing a continuum of modes, to unlock nonreciprocity and frequency translation over wide optical bandwidths in silicon. Using a traveling-wave phonon field to drive indirect interband photonic transitions, we demonstrate band hybridization that enables an intriguing form of nonreciprocal dissipation engineering. Using the converted mode to create a nonreciprocal dissipation channel, we demonstrate a frequency-neutral, low-loss (less than 1 dB) isolator with high nonreciprocal contrast (more than 14 dB) and broad operating bandwidth (more than 59 GHz). Additionally, through the implementation of complete interband conversion, we demonstrate a high extinction (more than 55 dB) optical frequency translation operation with near-unity efficiency.
... 5 Notably, microcombs can exhibit high conversion efficiency 6,7 and even achieve nearly lossless efficient operation 8 when paired with photonic-crystal gratings. [9][10][11] Their high spectral coherence properties 12 further enhance their applicability in various domains, ranging from data communication [13][14][15][16][17] through spectroscopy [18][19][20] to frequency synthesis. 21 One of the pivotal aspects of microresonator frequency combs is the ability to design and manipulate factors influencing nonlinear propagation like group-velocity dispersion (GVD, hereafter dispersion). ...
Microresonator frequency combs and their design versatility have revolutionized research areas from data communication to exoplanet searches. While microcombs in the 1550 nm band are well documented, there is interest in using microcombs in other bands. Here, we demonstrate the formation and spectral control of normal-dispersion dark soliton microcombs at 1064 nm. We generate 200 GHz repetition rate microcombs by inducing a photonic bandgap of the microresonator mode for the pump laser with a photonic crystal. We perform the experiments with normal-dispersion microresonators made from Ta2O5 and explore unique soliton pulse shapes and operating behaviors. By adjusting the resonator dispersion through its nanostructured geometry, we demonstrate control over the spectral bandwidth of these combs, and we employ numerical modeling to understand their existence range. Our results highlight how photonic design enables microcomb spectra tailoring across wide wavelength ranges, offering potential in bioimaging, spectroscopy, and photonic-atomic quantum technologies.
... An example of a commercial SiPh interface is TeraPHY, 9 which supports up to 2 Tb/s bandwidth per chiplet. Recently, a promising Kerr frequency combdriven SiPh transceiver architecture 15 has been reported, driven by an integrated frequency comb 16 DWDM light source and using (de-) interleavers to split and combine wavelength channels in order to achieve massive parallelism and scale up the data transmission bandwidth within a single fiber. In both of these examples, SiPh resonators are used to both perform wavelength-selective modulation and photodetection on the transmitter and receiver ends of the photonic integrated circuit (PIC) architecture, respectively. ...
... As a result of their inherent wavelength selectivity, compact footprint, and efficient resonance tuning (thermally or otherwise), SiPh resonators are ubiquitous in integrated DWDM systems. 15,33,35,56,57 Furthermore, SiPh resonator-based DWDM systems boast unrivaled design flexibility at both device and system levels due to the development of parameterized models that accurately capture the physical device behavior. 58,59 These parameterized models can be used to develop resonators for both add-drop (de)multiplexing filters 60,61 as well as active high-speed modulators; 23,24,62 applications even exist utilizing their non-linear phase response near resonance, such as ringassisted MZI (RAMZI) devices. ...
... Depletion mode index modulators can support tens of GHz bandwidth per-carrier wavelength, and integrating them into resonant devices allows for error-free data transmission to be achievable at CMOS-compatible drive voltages. 7,15,23,79 Furthermore, modulation by charging and discharging the junction capacitance, C j , does not consume DC power, and the energy per bit can be calculated as E bit ¼ 1=4C j V 2 pp , allowing for reported % 1 fJ/bit modulation efficiency up to data rates of 25 Gbps. 23 Figure 13 illustrates the fundamental operating principles for a depletion mode resonant modulator. ...
The growth of artificial intelligence applications demands ever larger and more complex deep learning models, dominating today's—and tomorrow's—data center and high-performance computing systems. While traditional electronics are failing to keep pace with application demands, silicon photonic (SiPh) interconnects have emerged as a necessary technology to support these systems. SiPh-driven wavelength-division multiplexing (WDM) offers a particularly promising path toward supporting incredibly high-aggregate link bandwidth in a compact and efficient form factor. One of the basic building blocks of these integrated WDM interconnects is the SiPh resonator. Their inherent wavelength selectivity and compact footprint allow for efficient data transmission multiplexed across dozens of carrier wavelengths. Used as add-drop (AD) filters, SiPh resonators are critical to constructing integrated tunable wavelength-selective optical circuit switches as well as for demultiplexing the different carrier wavelengths toward independent wavelength-insensitive photodiodes in a dense wavelength-division multiplexing receiver. Resonators in the all-pass (AP) configuration are widespread as well, allowing for wavelength-selective modulation to drive aggregate link bandwidths far beyond the individual channel data rate. Unlike SiPh Mach–Zehnder modulators (MZM), resonant modulators can be driven using low, complementary metal-oxide-semiconductor drive voltages, allowing for tight co-integration between photonic integrated circuits, fabricated with larger process node technologies, and electronic integrated circuits, designed to exploit the advantages of the latest node. To push toward practical peta-scale interconnects, a comprehensive review of SiPh resonators is required, addressing bottlenecks and design constraints at both the architecture and device levels. We first describe the predominant integrated link architectures and identify their limits. We then discuss the device-level design considerations that can be made for both AD and AP configuration resonators to overcome the system level limits with novel resonator device designs. Analytical models and numerical simulation of resonators are validated by experimental measurement of devices fabricated in a commercial 300-mm foundry, showing a clear path toward volume manufacturing. The demonstrated resonant modulators and filters support the feasibility of increasing the aggregate bandwidth of resonator-driven SiPh interconnects into the peta-scale regime.
... Similar to the advancements in the electronics industry, photonics research is steadily transferring an expanding repertoire of functionalities onto integrated platforms [1]. The combination of best-in-class materials at the wafer-level increases versatility and performance [2], suitable for large-scale markets, such as datacentre interconnects [3,4], lidar for autonomous driving [5] or consumer health. These applications require mature integration platforms to sustain the production of millions of devices per year and provide efficient solutions in terms of power consumption and wavelength multiplicity for scalability. ...
Photonic integrated circuits utilize planar waveguides to process light on a chip, encompassing functions like generation, routing, modulation, and detection. Similar to the advancements in the electronics industry, photonics research is steadily transferring an expanding repertoire of functionalities onto integrated platforms. The combination of best-in-class materials at the wafer-level increases versatility and performance, suitable for large-scale markets, such as datacentre interconnects, lidar for autonomous driving or consumer health. These applications require mature integration platforms to sustain the production of millions of devices per year and provide efficient solutions in terms of power consumption and wavelength multiplicity for scalability. Chip-scale frequency combs offer massive wavelength parallelization, holding a transformative potential in photonic system integration, but efficient solutions have only been reported at the die level. Here, we demonstrate a silicon nitride technology on a 100 mm wafer that aids the performance requirements of soliton microcombs in terms of yield, spectral stability, and power efficiency. Soliton microcombs are reported with an average conversion efficiency exceeding 50%, featuring 100 lines at 100 GHz repetition rate. We further illustrate the enabling possibilities of the space multiplicity, i.e., the large wafer-level redundancy, for establishing new sensing applications, and show tri-comb interferometry for broadband phase-sensitive spectroscopy. Combined with heterogeneous integration of lasers, we envision a proliferation of high-performance photonic systems for applications in future navigation systems, data centre interconnects, and ranging.
Titanium:sapphire (Ti:sapphire) lasers have been essential for advancing fundamental research and technological applications, including the development of the optical frequency comb¹, two-photon microscopy² and experimental quantum optics3,4. Ti:sapphire lasers are unmatched in bandwidth and tuning range, yet their use is restricted because of their large size, cost and need for high optical pump powers⁵. Here we demonstrate a monocrystalline titanium:sapphire-on-insulator (Ti:SaOI) photonics platform that enables dramatic miniaturization, cost reduction and scalability of Ti:sapphire technology. First, through the fabrication of low-loss whispering-gallery-mode resonators, we realize a Ti:sapphire laser operating with an ultralow, sub-milliwatt lasing threshold. Then, through orders-of-magnitude improvement in mode confinement in Ti:SaOI waveguides, we realize an integrated solid-state (that is, non-semiconductor) optical amplifier operating below 1 μm. We demonstrate unprecedented distortion-free amplification of picosecond pulses to peak powers reaching 1.0 kW. Finally, we demonstrate a tunable integrated Ti:sapphire laser, which can be pumped with low-cost, miniature, off-the-shelf green laser diodes. This opens the doors to new modalities of Ti:sapphire lasers, such as massively scalable Ti:sapphire laser-array systems for several applications. As a proof-of-concept demonstration, we use a Ti:SaOI laser array as the sole optical control for a cavity quantum electrodynamics experiment with artificial atoms in silicon carbide⁶. This work is a key step towards the democratization of Ti:sapphire technology through a three-orders-of-magnitude reduction in cost and footprint and introduces solid-state broadband amplification of sub-micron wavelength light.
We report the first O-band coherent transmission using a comb laser and a silicon photonics modulator. We achieved greater than 8.5 Tbps using 19 lines over 10km at 56 Gbaud DP-32QAM.
We demonstrate a vertical-junction microdisk modulator with interleaved RF contacts and doped-silicon heater. We measure a resonance ER=36.5 dB, FSR=27.15 nm, and open eye diagrams at 32 Gb/s NRZ with 800 mV peak-to-peak driving signal.
