Modern lens designs are capable of resolving greater than 10 gigapixels, while advances in camera frame-rate and hyperspectral imaging have made data acquisition rates of Terapixel/second a real possibility. The main bottlenecks preventing such high data-rate systems are power consumption and data storage. In this work, we show that analog photonic encoders could address this challenge, enabling high-speed image compression using orders-of-magnitude lower power than digital electronics. Our approach relies on a silicon-photonics front-end to compress raw image data, foregoing energy-intensive image conditioning and reducing data storage requirements. The compression scheme uses a passive disordered photonic structure to perform kernel-type random projections of the raw image data with minimal power consumption and low latency. A back-end neural network can then reconstruct the original images with structural similarity exceeding 90%. This scheme has the potential to process data streams exceeding Terapixel/second using less than 100 fJ/pixel, providing a path to ultra-high-resolution data and image acquisition systems.
We report on a two-step technique for post-bond III-V substrate removal involving precision mechanical milling and selective chemical etching. We show results on GaAs, GaSb, InP, and InAs substrates and from mm-scale chips to wafers.
We report on a two-step technique for post-bond III-V substrate removal involving precision mechanical milling and selective chemical etching. We show results on GaAs, GaSb, InP, and InAs substrates and from mm-scale chips to wafers.
Cryogenic environments make superconducting computing possible by reducing thermal noise, electrical resistance and heat dissipation. Heat generated by the electronics and thermal conductivity of electrical transmission lines to the outside world constitute two main sources of thermal load in such systems. As a result, higher data rates require additional transmission lines which come at an increasingly higher cooling power cost. Hybrid or monolithic integration of silicon photonics with the electronics can be the key to higher data rates and lower power costs in these systems. We present a 4-channel wavelength division multiplexing photonic integrated circuit (PIC) built from modulators in the AIM Photonics process development kit (PDK) that operate at 25 Gbps at room temperature and 10 Gbps at 40 K. We further demonstrate 2-channel operation for 20 Gbps aggregate data rate at 40 K using two different modulators/wavelengths, with the potential for higher aggregate bit rates by utilizing additional channels.
Heterogeneous Integration (HI) may enable optoelectronic transceivers for short-range and long-range radio frequency (RF) photonic interconnect using wavelength-division multiplexing (WDM) to aggregate signals, provide galvanic isolation, and reduce crosstalk and interference. Integration of silicon Complementary Metal-Oxide-Semiconductor (CMOS) electronics with InGaAsP compound semiconductor photonics provides the potential for high-performance microsystems that combine complex electronic functions with optoelectronic capabilities from rich bandgap engineering opportunities, and intimate integration allows short interconnects for lower power and latency. The dominant pure-play foundry model plus the differences in materials and processes between these technologies dictate separate fabrication of the devices followed by integration of individual die, presenting unique challenges in die preparation, metallization, and bumping, especially as interconnect densities increase. In this paper, we describe progress towards realizing an S-band WDM RF photonic link combining 180 nm silicon CMOS electronics with InGaAsP integrated optoelectronics, using HI processes and approaches that scale into microwave and millimeter-wave frequencies.
We demonstrate a platform for phase and amplitude modulation in silicon nitride photonic integrated circuits via piezo-optomechanical coupling using tightly mechanically coupled aluminum nitride actuators. The platform, fabricated in a CMOS foundry, enables scalable active photonic integrated circuits for visible wavelengths, and the piezoelectric actuation functions without performance degradation down to cryogenic temperatures. As an example of the potential of the platform, we demonstrate a compact (∼40 µm diameter) silicon nitride ring resonator modulator operating at 780 nm with intrinsic quality factors in excess of 1.5 million, >10 dB change in extinction ratio with 2 V applied, a switching time less than 4 ns, and a switching energy of 0.5 pJ/bit. We characterize the exemplary device at room temperature and 7 K. At 7 K, the device obtains a resistance of approximately 20 teraohms, allowing it to operate with sub-picowatt electrical power dissipation. We further demonstrate a Mach-Zehnder modulator constructed in the same platform with piezoelectrically tunable phase shifting arms, with 750 ns switching time constant and 20 nW steady-state power dissipation at room temperature.
Phase errors in large optical phased arrays degrade beam quality and must be actively corrected. Using a novel, low-power electro-optic design with matched pathlengths, we demonstrate simplified optimization and reduced sensitivity to wavelength and temperature.
Photonic integrated circuits provide a compact and stable platform for quantum photonics. Here we demonstrate a silicon photonics quantum key distribution (QKD) encoder in the first high-speed polarization-based QKD field tests. The systems reach composable secret key rates of 1.039 Mbps in a local test (on a 103.6-m fiber with a total emulated loss of 9.2 dB) and 157 kbps in an intercity metropolitan test (on a 43-km fiber with 16.4 dB loss). Our results represent the highest secret key generation rate for polarization-based QKD experiments at a standard telecom wavelength and demonstrate photonic integrated circuits as a promising, scalable resource for future formation of metropolitan quantum-secure communications networks.
We demonstrate a silicon photonic transceiver circuit for high-speed discrete variable quantum key distribution that employs a common structure for transmit and receive functions. The device is intended for use in polarization-based quantum cryptographic protocols, such as BB84. Our characterization indicates that the circuit can generate the four BB84 states (TE/TM/45°/135° linear polarizations) with >30 dB polarization extinction ratios and gigabit per second modulation speed, and is capable of decoding any polarization bases differing by 90° with high extinction ratios.
We demonstrate a silicon photonic transceiver circuit to implement polarization encoding/decoding for DV-QKD. The circuit is capable of encoding BB84 states with >30 dB PER and decoding with >20 dB ER.
Long, Christopher M.; Mickovic, Zlatko; Dwir, Benjamin; Caliman, Andrei; Iakovlev, Vladimir; Mereuta, Alexandru; Sirbu, Alexei; Kapon, Eli
Polarization mode control is enhanced in wafer-fused vertical-cavity surface-emitting lasers emitting at 1310 nm wavelength by etching two symmetrically arranged arcs above the gain structure within the laser cavity. The intracavity patterning introduces birefringence and dichroism, which discriminates between the two polarization states of the fundamental transverse modes. We find that the cavity modifications define the polarization angle at threshold with respect to the crystal axes, and increase the gain anisotropy and birefringence on average, leading to an increase in the polarization switching current. As a result, experimental measurements are explained using the spin-flip model of VCSEL polarization dynamics.