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We demonstrate a robust, scalable fiber packaging solution using dry-etched self-alignment features on chip. A 30x singlemode fiber array is packaged to SiN-based photonic edge couplers with

The integration of MEMS transducers in photonic integrated circuits provides opportunities for high efficiency photonic modulation and dynamic routing on-chip. We here present an electrostatically actuated, silicon photonic MEMS $2 \times 2$ power coupler, fabricated in IMEC's iSiPP50G platform followed by a dedicated MEMS release sequence. The in-plane, mechanical tuning mechanism provides analog power coupling between waveguides in a small form factor. With our experimental demonstration of broad, > 30 nm optical bandwidth, high extinction ratio of > 27 dB, and a low actuation voltage of only 6 V, the coupler fulfills the requirements for large-scale integration in next generation reconfigurable PICs.

MEMS enable low power tuners in silicon photonics, but existing phase shifters lack in range, speed, and loss. We implement a 2π phase shifter with a 1.54 μs time constant and 0.5 dB insertion loss in IMEC’s iSiPP50G platform.

Photonic integrated circuits are becoming increasingly more complex, especially with the emergence of programmable photonic circuits. These require many tunable photonic elements, such as electro-optic phase shifters and tunable couplers. We will discuss our progress in compact, low-power silicon photonics actuators based on heaters, liquid crystal and MEMS that can be scaled up to large circuits. (c) 2021TheAuthor(s)

Photonic crystal (PhC) nanocavities have demonstrated unique capabilities in terms of light confinement and manipulation. As such, they are becoming attractive for developing novel resonance-based photonic integrated circuits (PICs). Here two essential challenges arise however-how to realize ultrahigh quality factor (Q) PhC cavities using standard fabrication processes compatible with large volume fabrication, and how to efficiently integrate them with existing building blocks. In this work, ultrahigh-Q one-dimensional (1D) PhC nanocavities fabricated on a 300 mm silicon-on-insulator wafer are demonstrated by optical lithography, with a record Q factor of up to 0.84 million. Moreover, efficient mode management in those cavities is shown by coupling them with an access waveguide, realizing two critical components: notch filters and narrow-band reflectors. In particular, they allow both single-wavelength and multi-wavelength operation, at the desired resonant wavelengths, over a broad wavelength range (>100 nm). Compared to traditional cavities, this offers a fantastic strategy for implementing resonances precisely in PIC designs with more freedom in terms of wavelength selectivity and the control of mode number. Given their compatibility with optical lithography and compact footprint, the realized 1D PhC nanocavities will be of profound significance for designing compact and novel resonance-based photonic components on large scale.

We report O-band GeSi quantum-confined Stark effect waveguide-coupled electro- absorption modulator with 50GHz bandwidth. Static extinction ratio of 5.2dB, insertion loss of 7.6dB and 60Gb/s NRZ-OOK operation are shown for a 2V swing.

We present a silicon photonics technology extended with low-power MEMS scalable to large circuits. This enables us to make photonic waveguide meshes that can be reconfigured using electronics and software.

Silicon (Si) photonic micro-electro-mechanical systems (MEMS), with its low-power phase shifters and tunable couplers, is emerging as a promising technology for large-scale reconfigurable photonics with potential applications for example in photonic accelerators for artificial intelligence (AI) workloads. For silicon photonic MEMS devices, hermetic/vacuum packaging is crucial to the performance and longevity, and to protect the photonic devices from contamination. Here, we demonstrate a wafer-level vacuum packaging approach to hermetically seal Si photonic MEMS wafers produced in the iSiPP50G Si photonics foundry platform of IMEC. The packaging approach consists of transfer bonding and sealing the silicon photonic MEMS devices with 30 µm-thick Si caps, which were prefabricated on a 100 mm-diameter silicon-on-insulator (SOI) wafer. The packaging process achieved successful wafer-scale vacuum sealing of various photonic devices. The functionality of photonic MEMS after the hermetic/vacuum packaging was confirmed. Thus, the demonstrated thin Si cap packaging shows the possibility of a novel vacuum sealing method for MEMS integrated in standard Si photonics platforms. QC 20210710 MORPHiC ZeroAMP ULISSES

Photonic Integrated Circuits (PICs) benefit from the technology advances in the semiconductor industry to incorporate an ever-increasing number of photonic components on a single chip to create large-scale photonic integrated circuits. We here present a broadband, compact and low-loss Silicon Photonic MEMS switch based on a Single-Pole Double-Throw (SPDT) architecture, where curved electrostatic actuators mechanically displace a movable input waveguide to redirect the optical signal on chip efficiently to either of two output waveguides. The photonic switch has been fabricated in an established silicon photonics technology platform with custom MEMS release post-processing. With a compact footprint of $\mathbf 65\times 62\, \boldsymbol μ \mathbf m^\mathbf 2$ , the switch exhibits an extinction ratio exceeding 23 dB over 70 nm optical bandwidth, a low insertion loss and a fast response time below $1 μ \texts$ , meeting the requirements for integration in large-scale reconfigurable Photonic Integrated Circuits. [2020-0391] QC 20210607 MORPHIC

We demonstrate a compact add-drop filter based on a MEMS ring resonator implemented in IMEC's iSiPP50G silicon photonics platform. The device exhibits a port extinction of 20 dB and a port isolation of > 50 dB, upon actuation range of 0 V to 27 V.

Micro-transfer-printing (µTP) enables the intimate integration of a variety of III-V opto-electronic components on silicon photonic integrated circuits (Si PICs). It allows for the scalable manufacturing of complex III-V/Si PICs at low cost.

The dark current behavior of three different Ge waveguide photodiode designs integrated in a silicon photonics platform is investigated from 34 to 334 K. The activation energy is extracted to understand the relative contribution of Shockley-Read-Hall and trap-assisted tunneling at different temperatures and voltage biases.

We report on a waveguide-coupled quantum-confined Stark effect (QCSE) electro-absorption modulator integrated in a 220nm Si photonics platform and operating in 1335-1365nm wavelength range. The device is based on a strain -balanced GeSi quantum well / barrier stack grown on an ultra-thin strain-relaxed buffer. The stack is only 450nm thick, facilitating optical coupling to sub-micron Si waveguides. An extinction ratio up to 8dB is achieved in a $40\mu \mathrm{m}$ long device for a 1 Vpp drive voltage, demonstrating the potential of this modulator for low-power optical interconnect applications.

Programmable photonic circuits electronically reconfigure the flow of light on a chip. This requires hundreds or thousands of phase shifters and tunable couplers. Silicon photonic MEMS offer both high integration density and low power consumption.

In the European project MORPHIC we develop a platform for programmable silicon photonic circuits enabled by waveguide-integrated micro-electro-mechanical systems (MEMS). MEMS can add compact, and low-power phase shifters and couplers to an established silicon photonics platform with high-speed modulators and detectors. This MEMS technology is used for a new class of programmable photonic circuits, that can be reconfigured using electronics and software, consisting of large interconnected meshes of phase shifters and couplers. MORPHIC is also developing the packaging and driver electronics interfacing schemes for such large circuits, creating a supply chain for rapid prototyping new photonic chip concepts. These will be demonstrated in different applications, such as switching, beamforming and microwave photonics.

MEMS offer low power tunability to silicon photonics. However, reported phase shifters lack in range, IL, or linearity. We show pi linear phase shift in compact, 0.2 dB-IL MEMS devices, and demonstrate trade-offs for scalability. (C) 2020 The Author(s)

We present the demonstration of an integrated frequency modulated continuous wave LiDAR on a silicon platform. The waveform calibration, the scanning system, and the balanced detectors are implemented on a chip. Detection and ranging of a moving hard target at upto 60 m with less than 5 mW of output power is demonstrated in this paper.

A 16×16 silicon photonic switch circuit suitable for non-volatile operations has been realized. The switch circuit consists of dilated switch elements with liquid-controlled adiabatic waveguide couplers. The switch with a cross-bar architecture is compatible with a non-volatile electrowetting-on-dielectric system for optical actuation. The measured fiber-to-fiber loss is less than 18.9 dB over the wavelength range from 1500 to 1630 nm. At a wavelength of 1550 nm, the loss is between 8.5 and 17.4 dB depending on the length of the light path. The crosstalk of the switch is better than -50 dB over the wavelength range from 1500 to 1630 nm.

In this letter, we demonstrate a compact optical switch realized by integrating a graphene layer with a silicon photonic crystal cavity fabricated using deep UV immersion lithography and a novel transfer printing approach. A 17-dB extinction ratio and 0.75-nm shift in the cavity resonance are measured for a swing voltage of only 1.2 V. The graphene layer is limited to $\mu $ m in size. The experimental results are linked to a theoretical model and used to predict possible improvements to the design.

We present active components developed in imec's silicon photonics platform that enable 50-Gb/s non-return-to-zero operation using CMOS compatible voltages.

We demonstrate 100-Gbps silicon-contacted germanium waveguide p-i-n photodetectors integrated on imec's silicon photonics platform. The performance of 14 and 20 μm long devices is compared. The responsivity of the devices is 0.74 and 0.92 A/W at 1550 nm, respectively.

We demonstrate 60Gb/s NRZ and 100Gb/s PAM4 data modulation with an O-band silicon ring modulator with only 1.6V pp and 2.5V pp drive swing respectively, leveraging the large modulation efficiency (55pm/V) and electro-optical bandwidth (35GHz) realized by an optimized vertical PN diode phase shifter design.

We demonstrate a 67 GHz bandwidth silicon-contacted germanium waveguide p-i-n photodetector operating at −1 V with 6.8 fF capacitance. The dark current is below 4 nA. The responsivity is 0.74 A/W at 1550 nm and 0.93 A/W at 1310 nm wavelength. 56 Gbps on-off-keying data reception is demonstrated with clear open eye diagrams in both the C-band and O-band.

Silicon-based photonic integrated circuits (PICs) operating in the mid-infrared wavelength range are presented. Firstly, it is shown that the operation of the SOI-based waveguide circuits can be pushed beyond the telecom window till a wavelength of 4 μm. Ge-on-Si based PICs are demonstrated for operation beyond 4 μm wavelength. Low-loss waveguides and integrated spectrometers are reported for both the waveguide platforms. We also present our results on efficient thermo-optic phase shifters for germanium waveguide circuits.

In this paper we report a single mode InAs/GaAs quantum dot distributed feedback laser at 1.3 μm wavelength heterogeneously integrated on a Si photonics waveguide circuit. Single mode lasing around 1300 nm with a side-mode suppression ratio higher than 40 dB is demonstrated. High temperature operation with continuous wave lasing up to 100°C is obtained. Threshold current densities as low as 205 A/cm2 were measured. These devices are attractive candidates to use in uncooled silicon photonic transceivers in data centers.

We review our work on SOI and Ge-on-SOI PICs for the mid-infrared. We demonstrate the integration of III-V semiconductors on the SOI platform for 2–4 μm wavelength range integrated lasers and spectrometers, as well as tunable filters implemented on the Ge-on-SOI platform beyond 4μm.

We demonstrate a microbump flip-chip integrated 14nm-FinFET CMOS-Silicon Photonics (SiPh) technology platform enabling ultra-low power Optical I/O transceivers with 1.6Tb/s/mm2 bandwidth density. The transmitter combines a differential FinFET driver with a Si ring modulator, enabling 40Gb/s NRZ optical modulation at 154fJ/bit dynamic power consumption in a 0.015mm2 footprint. The receiver combines a FinFET trans-impedance amplifier (TIA) with a Ge photodiode, enabling 40Gb/s NRZ photodetection with −10.3dBm sensitivity at 75fJ/bit power consumption, in a 0.01mm2 footprint. High-quality data transmission and reception is demonstrated in a loop-back experiment at 1330nm wavelength over standard single mode fiber (SMF) with 2dB link margin. Finally, a 4×40Gb/s, 0.1mm2 wavelength-division multiplexing (WDM) transmitter with integrated thermal control is demonstrated, enabling Optical I/O scaling substantially beyond 100Gb/s per fiber.

We have designed, fabricated and tested edge couplers for silicon photonics with etched lenses targeting industry-standard SMF-28 fibers as well as future alignment and dust-tolerant expanded-beam connectors. These edge couplers are based on a Si inverse taper combined with a SiON ridge waveguide and etched lens fabricated on a silicon-on-insulator (SOI) platform. The lens structures were designed for coupling to SMF-28 fibers with a 1/e mode field diameter (MFD) of 10.4 micrometers in the telecommunications C-band. Alternate lens designs targeted expanded beams with 30 micrometer horizontal MFD. The measured SMF-28 lensed couplers exhibited a 1 dB bandwidth exceeding 150 nanometers, polarization dependent loss (PDL) of less than 1 dB and coupling efficiency better than -4.8 dB across the S-, C- and L-bands with only horizontal beam expansion.

Heterogeneously integrating III-V materials on silicon photonic integrated circuits has emerged as a promising approach to make advanced laser sources for optical communication and sensing applications. Tunable semiconductor lasers operating in the 2-2.5 mu m range are of great interest for industrial and medical applications since many gases (e.g., CO2, CO, CH4) and biomolecules (such as blood glucose) have strong absorption features in this wavelength region. The development of integrated tunable laser sources in this wavelength range enables low-cost and miniature spectroscopic sensors. Here we report heterogeneously integrated widely tunable III-V-on-silicon Vernier lasers using two silicon microring resonators as the wavelength tuning components. The laser has a wavelength tuning range of more than 40 nm near 2.35 mu m. By combining two lasers with different distributed Bragg reflectors, a tuning range of more than 70 nm is achieved. Over the whole tuning range, the side-mode suppression ratio is higher than 35 dB. As a proof-of-principle, this III-V-on-silicon Vernier laser is used to measure the absorption lines of CO. The measurement results match very well with the high-resolution transmission molecular absorption (HITRAN) database and indicate that this laser is suitable for broadband spectroscopy. (C) 2018 Chinese Laser Press

Within the European Project TERABOARD, a photonic integration platforms including electronic-photonic integration is developed to demonstrate high bandwidth high-density modules and to demonstrate cost and energy cost target objectives. Large count high bandwidth density EO interfaces for onboard and intra-data center interconnection are reported. For onboard large count interconnections a novel concept based on optical-TSV interconnection platform with no intersections and no WDM multiplexing is reported. All input/output coupler arrays based on a pluggable silica platform are reported as well.

We discuss recent progress in the performance of modulators and photodetectors co-integrated in a silicon photonics platform, and capable of operation in the O-band or C-band at 56Gb/s single-lane NRZ data rates and beyond.

We address the challenges in realizing low-loss, broadband optical interfaces for high-density fiber or polymer waveguides along with through-silicon via interconnects in a 50 GHz silicon photonics interposer platform suitable for 2.5D/3D packaging with advanced CMOS logic.

We have designed, fabricated and tested edge couplers for silicon photonics targeting industry-standard SMF-28 fibers. These edge couplers are based on a SiN inverse taper fabricated on a silicon-on-insulator (SOI) platform combined with an etch-based substrate removal process that prevents leakage of the expanded mode to the underlying silicon substrate. The measured couplers exhibited a 0.5 dB bandwidth exceeding 100 nm, polarization dependent loss (PDL) of less than 0.5 dB and coupling efficiency of approximately −3 dB in O-band. Similarly, a 1 dB bandwidth exceeding 100 nm, PDL less than 1 dB and coupling efficiencies of −3 dB and better than −4 dB for TE and TM modes respectively were demonstrated across the C- and L-bands.

We demonstrate a phase shifter using a silicon slot waveguide infiltrated with liquid crystal. For a 1-mm long device we achieve $73\pi $ phase shift with a 5 V voltage, with a voltage-length product of 0.0224 $\text{V}\cdot $ mm $\sim 1$ V. We drive the phase shifter with a digital 1 V, duobinary pulsewidth-modulated signal, or a 1 V frequency-modulated signal. This enables direct digital CMOS control of an analog optical phase shifter.

We demonstrate low-voltage waveguide-coupled germanium avalanche photodetectors (APDs) with a (wafer-scale mean) gain $\times$ bandwidth product of 140 GHz at $-$ 5 V by utilizing a 185-nm-thick Ge layer. An optical receiver based on such an APD operating up to 25 Gb/s is demonstrated.

Picosecond-pulse III-V-on-silicon mode-locked lasers based on linear and ring extended cavity geometries are presented. In passive mode-locked operation a 12 kHz -3dB linewidth of the fundamental RF tone at 4.7 GHz is obtained for the linear cavity geometry and 16 kHz for the ring cavity geometry. Stabilization of the repetition rate of these devices using hybrid mode-locking is also demonstrated.

We demonstrate 17 dB extinction ratio in an electrically gated graphene-integrated silicon photonic crystal cavity by applying −1.2 V gate voltage. The shift of resonance wavelength for the same voltage range is 0.75 nm. The size of the graphene layer is only 5 μm2.

We demonstrate single-wavelength, serial and real-time 100 Gb/s NRZ-OOK transmission over 500 m SSMF with a GeSi EAM implemented on a silicon photonics platform. The device was driven with 2 Vpp without 50 Ω termination, allowing a low-complexity solution for 400 GbE short-reach optical interconnects.

A 16-channel spatial-division multiplexed transceiver is demonstrated using a multicore fiber coupled to a dense array of co-integrated 56Gb/s GeSi electro-absorption modulators and photodetectors, realizing 896Gb/s aggregate bi-directional bandwidth in 1.47mm2 silicon footprint.

The next generations of data centers require a scalable optical transceiver technology. In this paper we present a silicon photonics platform supporting single-channel data rates of 50Gb/s and above. Advanced process options include 50GHz GeSi electro-absorption modulators, high efficiency thermo-optic phase shifters with P-pi

Yi Yu acknowledges the financial support from the China Scholarship Council for her PhD Scholarship No. 201206110048. This research was conducted by the Australian Research Council Centre of Excellence for Ultrahigh Bandwidth Devices for Optical Systems (project number CE110001018). Support for this work was also provided by the FP7-ERC-MIRACLE project.

A compact wavelength-tunable 10-Gb/s silicon racetrack modulator with integrated thermo-optic heater is demonstrated by using a waveguide with an asymmetric cross section, combining the compact footprint of microdisk modulators with the design simplicity of regular racetrack or ring modulators. The outer perimeter of the asymmetric racetrack modulator is fully etched to maximize optical confinement, and the inner waveguide edge is shallowly etched to maintain an electrically conductive path to the embedded p-n diode and to control the propagation of the asymmetric optical mode and its coupling to the bus waveguide. The resistive heating elements based on highly doped Si strips are implemented at the outer edge of the modulator for thermo-optic control. The asymmetric modulators can be fabricated along with Si wire waveguides and shallowly etched fiber-grating couplers using a simple process flow involving just two Si-patterning steps. Devices with a bending radius of 10 mu m and a novel "T"-shaped p-n diode layout have been fabricated, and exhibit electro-optic modulation and heater efficiencies of 28 pm/V and 42 pm/mW, respectively. At 10 Gb/s, a stable extinction ratio of 10 dB is demonstrated from a 2V(pp) drive swing, which can be maintained over a wavelength range of 4.6 nm by thermally tuning the modulator. This is equivalent with a temperature variation of about 62 degrees C.

We present a fully CMOS compatible frequency shifter device, in a I&Q dual Mach-Zehnder architecture. Frequency shift up to 410 MHz are obtained, with carrier and image sideband extinction from 27 to 51 dB.

Silicon photonics interposers enable low power, high bandwidth signal transfer between CMOS chips. Optical wave guides transfer the optical signal that carries the information. Optical modulator and detectors realize the optical to electrical signal transfer and vice versa. These components could be facing ESD stress during assembly. This work presents an in-depth study the self-protecting capabilities of these components and provides an ESD protection solution to increase the ESD robustness.

We demonstrate a silicon-contact-only 56 Gbps germanium waveguide photodetector operating at −1 V. The dark current is below 4 nA and the responsivity is 0.74 A/W at 1550 nm and 0.93 A/W at 1310 nm.

An integrated optical frequency shifter on a standard silicon photonics platform completely fabricated in a CMOS pilot line and showing MHz frequency shifts with a sideband suppression ratio up to 36 dB is demonstrated.