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We report a study on moisture effect on optical performance of monolithic silicon photonics technologies featuring V-grooves for self-aligned fiber attach. Chip-level hermetic sealing was achieved by implementing moisture barrier for the fiber coupler.

We experimentally demonstrated V-groove-based self-aligned SiN edge coupler (EC) on a monolithic CMOS-SiPh platform. 520 mW power handling capability were achieved.

Grating-assisted contra-directional couplers (CDCs) wavelength selective filters for wavelength division multiplexing (WDM) are designed and experimentally demonstrated. Two configuration setups are designed; a straight-distributed Bragg reflector (SDBR) and curved distributed Bragg reflector (CDBR). The devices are fabricated on a monolithic silicon photonics platform in a GlobalFoundries CMOS foundry. The sidelobe strength of the transmission spectrum is suppressed by controlling the energy exchange between the asymmetric waveguides of the CDC using grating and spacing apodization. The experimental characterization demonstrates a flat-top and low insertion loss (0.43 dB) spectrally stable performance (2/Ch (SDBR) and 3700µm2/Ch (CDBR).

We experimentally demonstrate wavelength-independent couplers (WICs) based on an asymmetric Mach-Zehnder interferometer (MZI) on a monolithic silicon-photonics platform in a commercial, 300-mm, CMOS foundry. We compare the performance of splitters based on MZIs consisting of circular and 3rd order (cubic) Bézier bends. A semi-analytical model is constructed in order to accurately calculate each device’s response based on their specific geometry. The model is successfully tested via 3D-FDTD simulations and experimental characterization. The obtained experimental results demonstrate uniform performance across different wafer sites for various target splitting ratios. We also confirm the superior performance of the Bézier bend-based structure, compared to the circular bend-based structure both in terms of insertion loss (0.14 dB), and performance consistency throughout different wafer dies. The maximum deviation of the optimal device’s splitting ratio is 0.6%, over a wavelength span of 100 nm. Moreover, the devices have a compact footprint of 36.3 × 3.8 μm2.

Developing efficient techniques to bridge single-plasmon radiations to nanoscale plasmonic waveguides nowadays is still a critical consideration for on-chip integration of solid-state photonic circuits. Here, we propose and theoretically demonstrate the generation and routing of single plasmons in nanowire-based hybrid plasmonic coupling structures with nanodisk antenna resonators. Optimizations of key characteristic parameters illustrate that the structure not only offers an enhanced tradeoff between the propagation length (∼20 μm) and mode confinement (∼ λ 2/8450), but also exhibits outstanding plasmon generation and guiding properties, such as a Purcell factor of 2.14 × 106, a coupling efficiency from emissions to desired waveguides of 59%, and a Figure-of-Merit of 3 × 107 in the visible and infrared spectral range, which outperforms the previous plasmonic structures. The plasmon emission properties are also quite robust against possible emitter positioning imperfections. Our work may inspire new opportunities in helping design quantum-plasmonic platforms for future quantum information processing and related on-chip plasmonic devices.

We experimentally demonstrate a compact and power efficient (Pπ = 21 mW) silicide-based thermo-optic phase shifter of length 96 µm for photonic neural networks.

We experimentally demonstrate fabrication-tolerant, arbitrary power splitters based on a Mach-Zehnder Interferometer (MZI). The devices exhibit maximum splitting ratio deviation of 1.2%, and maximum insertion loss of only 0.36 dB across the O-band.

We experimentally demonstrate wavelength-independent couplers based on an asymmetric Mach-Zehnder interferometer on a monolithic silicon-photonics platform in a state-of-the-art CMOS foundry. The devices are also designed to exhibit fabrication tolerant performance for arbitrary splitting ratios. We have developed a semi-analytical model to optimize the device response and the reliability of the model is benchmarked against 3D-FDTD simulations. Experimental results are consistent with the simulation results obtained by the model and show uniform performance across different wafer sites with a standard deviation for the splitting ratio of only 0.6% at 1310 nm wavelength. The maximum spectral deviation of the splitting ratio (3-dB splitter) is measured to be 1.2% over a wavelength range of at least 80 nm and the insertion loss ranges from 0.08 to 0.38 dB. The wavelength-independent coupler has a compact footprint of 60 × 40 μ m 2 .

We propose a ‘TSV-free’ solution to create three-dimensional (3D) silicon photonic (SiPh) components and interconnects based on phase matching. The evanescent coupling between interlevel optical stacks is comprehensively studied and leveraged to achieve flexible light control and realize hetero-stack communication in a monolithic SiPh platform. Various 3D functional photonic components, such as polarizers, polarization splitters and electro-absorption modulators are proposed and investigated. The TSV-free 3D optical interconnect provides a promising path towards low-cost, high-density SiPh chips for both monolithic and hybrid platforms, and potentially enables applications in a wide variety of fields such as LiDAR, artificial intelligence and optical biosensors.

We report the hybrid flip-chip integration of III-V laser on a monolithic silicon photonics (SiPh) platform. Wafer-scale laser attach was demonstrated with the assistance of a laser cavity on a Si substrate. The attach process was accomplished through precise optical and mechanical alignment features on the laser and SiPh wafer. Efficient laser-to-photonic integrated circuit (PIC) butt-coupling with optical power up to 11 dBm was achieved through a combination of precise mechanical stops and optical alignment features. Key laser performance metrics such as mode hopping and relative intensity noise (RIN) vs. reflectivity were also studied. The impact of laser-PIC alignment on the coupling efficiency was studied through comprehensive two-dimensional (2D) and three-dimensional (3D) numerical modeling. Simulations were also performed to explore different coupler designs for optimized laser coupling performance.

A competitive 300-mm silicon photonics foundry technology has been developed by GLOBALFOUNDRIES for general availability, which takes advantage of advanced CMOS process technology and provides a manufacturing scale. A state-of-the-art process design kit offers a codesign environment with access to a comprehensive photonics device library along with a monolithically integrated SOI CMOS device library. Advances in automated wafer-level optical test enable statistical photonic device characterization for development, photonic modeling, and manufacturing controls. The key challenges and solutions in developing a manufacturable photonic technology with state-of-the-art performance are described, as well as a roadmap for next generation high-performance monolithic silicon photonics are outlined.

A cost-efficient and low-complexity optical input/output (I/O) packaging solution is a substantial challenge for volume production of photonic integrated circuits. To address this, metamaterial fiber couplers are an attractive solution for integrated photonic devices especially for optical I/O, interfacing standard optical fibers to photonic chips. They offer the advantages of refractive index engineering to achieve better mode match as well as higher fabrication tolerances. Metamaterial waveguides, as a fundamental building block of these fiber couplers, have attracted tremendous attention in recent years. Here, we report on effective optical return loss control in Si metamaterial waveguide designs to achieve ultra-low reflection loss in CMOS-compatible silicon photonics implemented in a 300 mm production line. Low backscattering is a substantial consideration for a range of applications. Here, a return loss of better than − 30 d B is achieved.

We report a hybrid flip-chip-integrated laser attach technology on a monolithic SiPh platform. Efficient laser-to-PIC butt-coupling with optical power up to 11dBm was demonstrated through a combination of precise mechanical stops and optical alignment features.

We demonstrate a fully automated and flexible wafer level photonic device testing and characterization with wavelength, optical power, temperature, and voltage dependencies. High precision setup and data analysis tools are developed for photonic compact modeling.

We describe a fabrication tolerant WDM filter with cascaded MZI, using wavelength inde- pendent couplers (WICs). 3D FDTD simulations show broadband device operation with a spectral shift per waveguide width offset of 6.3 pm/nm.

We propose apodized DBR bends for a compact (0.0024 mm2/ch) 4 channel cWDM filter. Simulations show -39 dB sidelobe suppression, -32 dB cross-talk, and -0.05 dB insertion loss for an optimized device configuration.

We describe a Bézier curve-based wavelength-independent coupler using a Mach-Zehnder Interferometer (MZI). 3D FDTD simulations demonstrate constant, broadband splitting ratios with very low insertion loss (< 0.05 dB) and compact footprint (138μm2).

An ultra-compact TM-pass polarizer is numerically demonstrated by laterally coupling a stacked Si waveguide with vanadate strips. Results show a device of 3µm in length is capable of achieving an ultra-high extinction ratio of 40dB and a low insertion loss of 2.2dB at 1.55μm.

A hybrid laser attach technology was demonstrated on GLOBALFOUNDRIES 300-mm monolithic silicon photonics (SiPh) platform. High accuracy bonding of laser inside a cavity in the SiPh die was accomplished. Optical power up to 10dBm was demonstrated through direct butt-coupling of the laser to SiPh die.

We present a hybrid vanadate/silicon-photonics platform that integrates vanadate nanostructures with silicon-on-insulator (SOI) waveguides for high-performance functional passive building blocks at telecommunication wavelengths. Comprehensive numerical analysis is performed to study the mode hybridization in a hybrid waveguide structure that comprises a silicon ridge separated from a vanadate substrate. Studies on the impact of key geometric parameters reveal that the coupling between vanadate and photonic structures result in highly confined hybrid modes with extreme field confinement and significantly larger effective indices as compared to hybrid plasmon polarizations (HPPs) supported by noble-metal-based waveguiding systems. By leveraging the unique confinement and modal properties offered by vanadate material, we explore the feasibility of building ultra-compact waveguide attenuators and transverse-magnetic (TM)-pass polarizers based on proper combinations of vanadate and SOI configurations. Our studies indicate that a 5μm-long attenuator can simultaneously achieve over 30 dB absorption and a low optical return loss less than -27 dB for both transverse-electric (TE) and TM polarizations. In addition, through proper management of the interactions between vanadate and silicon modes with different polarizations, we numerically demonstrate an ultra-compact (3 μm) on-chip TM-pass polarizer featuring low insertion loss (~ 3 dB), in conjunction with an extinction ratio exceeding 22 dB. The integration of vanadate materials with SOI platforms thereby offers the potential to bridge a gap in conventional silicon photonic systems and opens new avenues towards scalable functional integrated silicon photonic devices at telecom bands.

The data communications industry has begun transitioning from electrical to optical interconnects in datacenters in order to overcome performance bottlenecks and meet consumer needs. To mitigate the costs associated with this change and achieve performance for 5G and beyond, it is crucial to explore advanced photonic devices that can enable high-bandwidth interconnects via wavelength-division multiplexing (WDM) in photonic integrated circuits. Subwavelength grating (SWG) filters have shown great promise for WDM applications. However, the small feature sizes necessary to implement these structures have prohibited them from penetrating into industrial applications. To explore the manufacturability and performance of SWG filters in an industrial setting, we fabricate and characterize O-band subwavelength grating filters using the monolithic photonics technology at GLOBALFOUNDRIES (GF). We demonstrate a low drop channel loss of -1.2 dB with a flat-top response, a high extinction ratio of -30 dB, a 3 dB channel width of 5 nm and single-source thermal tunability without shape distortion. This filter structure was designed using elements from the product design kit provided by GF and functions in a compact footprint of 0.002 mm2 with a minimum feature size of 150 nm., Comment: 4 pages, 3 figures

A beam shaping approach has been implemented to realize high-performance waveguide crossings based on cosine tapers. Devices with a compact footprint of 4.7 µm × 4.7 µm are implemented on a GLOBALFOUNDRIES monolithic silicon photonics platform. Fabricated devices are found to be nearly wavelength-independent (± 0.035 dB for 1260 nm ≤ λ ≤ 1360 nm) with low insertion loss (~ 0.2 dB) and crosstalk (< -35 dB). The measured response of the devices is consistent with simulation results obtained by 3D FDTD computations. The design stability is confirmed by measuring the device insertion loss over nine chips, which is found to be 0.197 ± 0.017 dB at the designed center wavelength of 1310 nm.

We review recent progress in loss reduction of Si and SiN waveguides in GLOBALFOUNDRIES 300mm monolithic Si photonics platform. Primary challenges to creating low-loss CMOS integrated photonic components are highlighted and potential solutions are outlined.