Showing papers by "Jason S. Orcutt published in 2016"

A 45 nm CMOS-SOI Monolithic Photonics Platform With Bit-Statistics-Based Resonant Microring Thermal Tuning

Abstract: The microring resonator is critical for dense wavelength division multiplexed (DWDM) chip-to-chip optical I/O, enabling modulation and channel selection at the $\upmu\text{m}$ -scale suitable for a VLSI chip. Microring-based links, however, require active tuning to counteract process and thermo-optic variations. Here, we present a bit-statistical tuner that decouples tracking of optical one- and zero-levels to realize non-dc-balanced data transmission, an “eye-max”-locking controller, and self-heating cancellation without need for a high-speed sensing frontend. We implement the tuner on a 45 nm CMOS-SOI process with monolithically integrated photonic devices and circuits. The tuner consumes 0.74 mW in the logic while achieving a record 524 GHz ( $>$ 50 K temperature) tuning range at $3.8\;\upmu\text{W/GHz}$ heater efficiency. To our knowledge, this is the highest range and heater efficiency reported by an on-chip closed-loop thermal tuner to date. The tuner integrates with a 5 Gb/s 30 fJ/bit monolithic microring transmitter, achieving wavelength-lock and immunity to both tracking failures and self-heating events caused by arbitrary, non-dc-balanced bitstreams. In addition, the tuner provides critical functionality for an 11- $\lambda$ DWDM transmitter macro capable of $11\ \times\ 8$ Gb/s bandwidth on a fiber. Together with the transmitter, a 10 Gb/s on-chip monolithic optical receiver with $10^{-{\textbf{12}}}$ BER sensitivity of $9\;\upmu\text{A}$ at 10 Gb/s enables a sub-pJ/bit 5 Gb/s optical chip-to-chip link, with the bit-statistical tuner providing thermally robust microring operation.

A monolithic 56 Gb/s silicon photonic pulse-amplitude modulation transmitter

Abstract: Silicon photonics promises to address the challenges for next-generation short-reach optical interconnects. Growing bandwidth demand in hyper-scale data centers and high-performance computing motivates the development of faster and more-efficient silicon photonics links. While it is challenging to raise the serial line rate, further scaling of the data rate can be realized by, for example, increasing the number of parallel fibers, increasing the number of wavelengths per fiber, and using multi-level pulse-amplitude modulation (PAM). Among these approaches, PAM has a unique advantage because it does not require extra lasers or a costly overhaul of optical fiber cablings within the existing infrastructure. Here, we demonstrate the first fully monolithically integrated silicon photonic four-level PAM (PAM-4) transmitter operating at 56 Gb/s and demonstrate error-free transmission (bit-error-rate < 10$^{-12}$) up to 50 Gb/s without forward error correction. The superior PAM-4 waveform is enabled by optimization of silicon traveling wave modulators and monolithic integration of the CMOS driver circuits. Our results show that monolithic silicon photonics technology is a promising platform for future ultrahigh data rate optical interconnects.

Monolithic 56 Gb/s silicon photonic pulse-amplitude modulation transmitter

Abstract: Silicon photonics promises to address the challenges for next-generation short-reach optical interconnects. Growing bandwidth demand in hyper-scale data centers and high-performance computing motivates the development of faster and more efficient silicon photonics links. While it is challenging to raise the serial line rate, further scaling of the data rate can be realized by, for example, increasing the number of parallel fibers, increasing the number of wavelengths per fiber, and using multilevel pulse-amplitude modulation (PAM). Among these approaches, PAM has a unique advantage because it does not require extra lasers or a costly overhaul of optical fiber cablings within the existing infrastructure. Here, we demonstrate, to our knowledge, the first fully monolithically integrated silicon photonic four-level PAM (PAM-4) transmitter operating at 56 Gb/s and demonstrate error-free transmission (bit-error rate <10−12) up to 50 Gb/s without forward-error correction. The superior PAM-4 waveform is enabled by co-design and co-optimization of the silicon traveling-wave modulators with the monolithic CMOS driver circuits. Our results show that monolithic silicon photonics technology is a promising platform for future ultrahigh data rate optical interconnects.

Ultralow crosstalk nanosecond-scale nested 2 × 2 Mach-Zehnder silicon photonic switch.

Abstract: We present the design and characterization of a novel electro-optic silicon photonic 2×2 nested Mach–Zehnder switch monolithically integrated with a CMOS driver and interface logic. The photonic device uses a variable optical attenuator in order to balance the power inside the Mach–Zehnder interferometer leading to ultralow crosstalk performance. We measured a crosstalk as low as −34.5 dB, while achieving ∼2 dB insertion loss and 4 ns transient response.

Demonstration of Error-Free 32-Gb/s Operation From Monolithic CMOS Nanophotonic Transmitters

Abstract: We present a monolithic CMOS-integrated nanophotonic transmitter with a link sensitivity comparable with a 25-Gb/s commercial reference transmitter. Our CMOS transmitter shows error-free operation up to 32 Gb/s, and exhibits a 4.8-dB extinction ratio and 4.9-dB insertion loss at 25 Gb/s.

Monolithic silicon photonics at 25 Gb/s

Abstract: Monolithic CMOS photonics seeks to minimize total transceiver cost by simplifying packaging, design and test. Here we examine 25 Gb/s applications in the context of integrated transistor performance and demonstrate a 4λ×25 Gb/s reference design.

Silicon photonic on-chip trace-gas spectroscopy of methane

Abstract: We demonstrate a silicon photonic chip sensor for absorption spectroscopy of methane near λ=1651 nm. Noise analysis demonstrates 8.5×10−4 Hz−1/2 minimum fractional absorption and Gaussian noise performance with 20 ppmv detection limit at ∼103 s.

An O-band Polarization Splitter-Rotator in a CMOS-Integrated Silicon Photonics Platform

Abstract: We demonstrate an adiabatic polarization splitter-rotator fabricated in a production CMOS-integrated Si photonic process. The measured insertion loss is ≤ 1.0dB and the polarization extinction is better than 27dB over the 60nm bandwidth measured.

Read out of quantum states of microwave frequency qubits with optical frequency photons

Abstract: Techniques relate to reading a qubit coupled to a microwave resonator. A microwave signal at a microwave resonator frequency is input to the microwave resonator that couples to the qubit. A microwave readout signal from the microwave resonator is output to a microwave to optical converter. The microwave readout signal includes a qubit state of the qubit. The microwave to optical converter is configured to convert the microwave readout signal to an optical signal. In response to the optical signal being output by the microwave to optical converter, it is determined that the qubit is in a predefined qubit state. In response to no optical signal being output by the microwave to optical converter, it is determined that the qubit is not in the predefined qubit state.

Semiconductor chip and method of configuring same

Abstract: A semiconductor chip and a method of configuring the same are provided. An optical gain chip is attached to a semiconductor substrate. An integrated photonic circuit is on the semiconductor substrate, and the optical gain chip is optically coupled to the integrated photonic circuit thereby forming a laser cavity. The integrated photonic circuit includes an active intra-cavity thermo-optic optical phase tuner element, an intra-cavity optical band-pass filter, and an output coupler band-reflect optical grating filter with passive phase compensation. The active intra-cavity thermo-optic optical phase tuner element, the intra-cavity optical band-pass filter, and the output coupler band-reflect optical grating filter with passive phase compensation are optically coupled together.

Silicon Photonics for On-Chip Trace-Gas Spectroscopy

Abstract: Natural gas leaks from production wells and pipelines pose a significant environmental risk due to the strong greenhouse effect caused by its main constituent, methane. We present a silicon photonic trace-gas sensing platform, which uses laser spectroscopy to realize cost-effective sensor networks for fugitive methane emission monitoring.

Guided-wave photodetector apparatus employing mid-bandgap states of semiconductor materials, and fabrication methods for same

Abstract: Guided-wave photodetectors based on absorption of infrared photons by mid-bandgap states in non-crystal semiconductors. In one example, a resonant guided-wave photodetector is fabricated based on a polysilicon layer used for the transistor gate in a SOI CMOS process without any change to the foundry process flow (‘zero-change’ CMOS). Mid-bandgap defect states in the polysilicon absorb infrared photons. Through a combination of doping mask layers, a lateral p-n junction is formed in the polysilicon, and a bias voltage applied across the junction creates a sufficiently strong electric field to enable efficient photo-generated carrier extraction and high-speed operation. An example device has a responsivity of more than 0.14 A/W from 1300 to 1600 nm, a 10 GHz bandwidth, and 80 nA dark current at 15 V reverse bias.

Self-clocked low noise photoreceiver (sclnp)

Abstract: A photoreceiver device includes a light detector connected between a power supply node and a first node, and first to third switching elements The light detector is configured to detect an incident optical data signal, and to output photocurrent corresponding to a magnitude of the optical data signal through the first node The first switching element is connected between the first node and a ground node The second switching element is connected between the power supply node and a second node The third switching element is connected between the second node and the ground node The third switching element has a control node connected to the first node