Intel Research announced significant advances in its integrated optoelectronics research, the next frontier in increasing the bandwidth of interconnecting computing chips within and across data centers. This latest research represents an industry-leading advance in multi-wavelength integrated optics, demonstrating an eight-wavelength distributed feedback (DFB) laser array fully integrated on a silicon wafer with output power uniformity of +/- 0.25 decibels (dB) and wavelength spacing uniformity of ±6.5%, both better than industry specifications.
This new research shows that uniformly dense wavelengths and well-matched output power can be achieved simultaneously and, most importantly, can be done using existing production and process control technologies in Intel’s fabs,” said Haisheng Rong, senior principal engineer at Intel Research. As such, it provides a clear path to volume production of next-generation optoelectronic co-packages and optical interconnect devices.”
Light sources produced using this new advancement will have the performance required for future large-scale applications, such as optoelectronic co-packaging and optical interconnect devices that can be used for those handling emerging network-intensive workloads such as AI and machine learning. This laser array is based on Intel’s 300mm silicon photonic process manufacturing, paving the way for mass production and widespread deployment.
Gartner predicts that by 2025, more than 20 percent of data center high-bandwidth channels will use silicon photonics, compared to less than 5 percent in 2020. In addition, the potential market for silicon photonics has reached $2.6 billion. The need for low power consumption, high bandwidth and fast data transmission has brought about a parallel growth in demand for silicon photonics to support data center applications and beyond.
Optical connectivity began replacing copper in the 1980s because the high-bandwidth optical transmission inherent in fiber optics was superior to the electrical pulses transmitted over metal cables. Since then, fiber optic technology has become more efficient due to reductions in component size and cost, leading to breakthroughs in optical interconnect networking solutions over the past few years that are commonly used in switches, data centers and other high-performance computing environments.
As electrical interconnect performance approaches its practical limits, the side-by-side integration of silicon circuits and optics on the same package promises to improve the energy efficiency of input/output (I/O) interfaces and extend their transmission distances in the future. These photonic technologies are implemented in Intel fabs using existing process technologies, which means their cost will be reduced when mass production is achieved.
The latest optoelectronic co-packaging solutions use dense wavelength division multiplexing (DWDM) technology, showing the promise of increasing bandwidth while significantly reducing the size of photonic chips. However, as of now, to manufacture a dense wavelength division multiplexing light source with uniform wavelength spacing and power is very difficult.
This new advancement by Intel ensures that light sources have uniform output power while maintaining consistent wavelength separation, meeting the needs of optical computing interconnects and dense wavelength division multiplexing communications. Next-generation input/output interfaces using optical interconnects can be tailored to the extremely high bandwidth requirements of future AI and machine learning workloads.
8 micro-loop modulators and optical waveguides. Each micro-ring modulator is tuned to a specific wavelength (or “color of light”). By using multiple wavelengths, each micro-ring can modulate the light waves individually for independent communication. This method of using multiple wavelengths is called wavelength division multiplexing. (Image credit: Intel Corporation)
The eight-wavelength distributed feedback laser array was designed and fabricated on Intel’s commercial 300 mm hybrid silicon photonic platform, which is used for mass production of optical transceivers. Based on the same, tightly process-controlled lithography used to manufacture 300 mm silicon wafers, this innovation represents a major leap forward in laser manufacturing capabilities for large CMOS fabs.
8-channel III-V/silicon hybrid distributed feedback laser array. By enabling matched power and uniform wavelength spacing, this innovation marks a significant leap forward in the ability of large fabs to mass produce multi-wavelength lasers.
In this study, Intel used advanced lithography to complete the configuration of waveguide gratings in silicon wafers prior to the III-V wafer bonding process. This technology improves wavelength uniformity compared to common semiconductor lasers fabricated in three- or four-inch III-V wafer fabs. In addition, due to the high-density integration of the laser, the array maintains stable channel spacing even when the ambient temperature changes.
In the future, as a pioneer in silicon photonic technology, Intel will continue to work on various types of solutions to meet the growing demand for a more efficient and versatile network infrastructure. Currently, Intel is developing integrated optoelectronic key building blocks including light generation, amplification, detection, modulation, CMOS interface circuits and package integration.
In addition, many aspects of eight-wavelength integrated laser array manufacturing technology are being used by Intel’s Silicon Photonics Products Division to build the optical interconnect cores of the future. This upcoming product will enable low-power, high-performance, multi-terabits per second interconnects between various computing resources, including CPUs, GPUs and memory. Integrated laser arrays are key to reducing size and cost for the mass manufacturing and deployment of optical interconnect cores.