Researchers have invented a new laser for the emitting surface of a vertical cavity, the workplace of data centers and optical sensors.
Researchers at George Washington University have developed a new design for a vertical cavity emitting surface laser (VCSEL) that shows a fast record bandwidth time. This was possible by combining a large number of transverse coupled cavities, which improves the optical feedback of the laser. VCSELs have emerged as an essential approach to the implementation of energy-efficient and high-speed optical interconnections in data centers and supercomputers.
VCSELs are an essential class of semiconductor laser diodes, along with a monolithic laser resonator that emits light perpendicular to the surface of the chip. This laser class is gaining importance in the market due to its compact size and high optoelectronic performance. As a miniaturized laser, they are used as an optical source in high-speed shortwave communications and optical data networks. Dense traffic and high-speed transmission are key requirements for automotive or data communications smart sensor applications, which are enabled by compact high-speed VCSELs. However, the 3-dB bandwidth, known as the VCSEL speed limit, is limited by thermal effects, parasite resistance, capacitance, and nonlinear gain effects.
The direct modulation of VCSEL cannot exceed about 30 GHz due to non-linear optical amplifications known as gain relaxation oscillations. This invention introduces the revolutionary novel VCSEL. Since the internal feedback of the laser must be carefully managed, the researchers presented a multi-feedback approach by combining multi-coupled cavities. This reinforced the so-called “slow light” view, thus extending the laser time bandwidth (speed) beyond the known limit of the relaxation oscillation frequency. The innovation is pioneering in that the direct feedback from each cavity must be moderate and can be precisely controlled through coupled cavities, allowing a higher level of freedom for design. Following this scheme of coupled cavities, a bandwidth modulation in the 100 GHz range is expected.
By the hand of researchers
“Here we present a paradigm shift in laser design. We use a new approach to coupled cavities to control laser feedback, significantly slowing laser light. This coupled cavity approach adds a new level of freedom to laser design, offering basic science and technology opportunities.”
– Volker Sorger, Associate Professor of Electrical and Computer Engineering at George Washington University.
“This invention is appropriate because the demand for data services is growing rapidly and is moving to next-generation communications networks like 6G, but also to the automotive industry as a proximity sensor or smartphone face ID. such as consistent Ising machines. “
– Dr. Hamed Dalir, author of the paper and inventor of technology
Reference: Elham Heidari, Hamed Dalir, Moustafa Ahmed, Volker J. Sorger, and Ray T. Chen, October 15, 2020, “Redefining VCSEL Hexagonal Indirect Coupling Cavities with High-Speed Lasers.” Nanophotonics.
DOI: 10.1515 / nanoph-2020-0437