Key Takeaways & Executive Findings
- •• Demonstrated a single-mode 850 nm VCSEL achieving 60 Gb/s NRZ and 104 Gb/s PAM4 modulation over 100 m OM5 fiber without equalization or filtering. • Optical injection locking enhanced the 3 dB bandwidth to 68.5 GHz, enabling ultra-high-speed operation. • The VCSEL design incorporates a double mesa structure and BCB for improved thermal management and high-speed performance. • Single-mode operation mitigates modal dispersion, extending transmission distance in VCSEL-MMF optical interconnects.
Abstract
A high-speed single-mode vertical-cavity surface-emitting laser (VCSEL) is one of the most important light sources for optical interconnects in data centers. Single-mode VCSEL can improve the transmission distance. In this letter, we demonstrate a single-mode 850 nm VCSEL with a bit rate of 60 Gb/s under NRZ modulation and 104 Gb/s under PAM4 modulation across a 100 m length of OM5 fiber, without the need for equalization or a filter. In addition, by using optical injection locking, the 3 dB bandwidth is enhanced to 68.5 GHz.
1. Introduction
Emerging information technologies, such as artificial intelligence (AI), are driving an exponential growth in data throughput within data centers, prompting continuous expansion of their scale. Intra data centers rely heavily on optical interconnects utilizing 850 nm multi-mode vertical-cavity surface-emitting lasers (VCSELs) and multi-mode fibers (MMFs), which offer high speed, cost efficiency, and low power consumption[1]. However, current VCSEL-MMF optical interconnects are constrained by limited effective modal bandwidth and significant transmission loss[2], restricting the distance of the data transmission.
Single-mode VCSELs offer a promising solution by mitigating modal dispersion, thereby extending the reach of VCSEL-MMF links to meet the demands of longer-distance optical interconnects[2]. Therefore, the research on high-speed and single-mode VCSELs carries substantial scientific importance. With the help of the equalization or filter, a 50 Gb/s non-return to zero (NRZ) transmission[3, 4] and 100 Gb/s 4-level pulse amplitude modulation (PAM4) transmission across a 100 m length OM5 fiber were reported[5−8]. The high-speed 850 nm VCSEL also has potential application in cryogenic optical interconnect for cryogenic computing[9].
In this letter, we demonstrate a single-mode 850 nm VCSEL with a bit rate of 60 Gb/s under NRZ modulation and 104 Gb/s under PAM4 modulation across a 100 m length of OM5 fiber, without the need for equalization or digital signal processing (DSP). In addition, by using optical injection locking (OIL)[10, 11], the 3 dB bandwidth is enhanced to 68.5 GHz.
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Si-Cong Tian (2025). High-speed single-mode 850 nm vertical-cavity surface-emitting laser. SinoTechIntel Verified Research. https://doi.org/10.1088/1674-4926/25090008
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Frequently Asked Questions
What is the maximum bit rate achieved by the single-mode 850 nm VCSEL?
The VCSEL achieves 60 Gb/s under NRZ modulation and 104 Gb/s under PAM4 modulation over 100 m of OM5 fiber without equalization or filtering.
How is the 3 dB bandwidth enhanced in this VCSEL?
By using optical injection locking, the 3 dB bandwidth is enhanced to 68.5 GHz.
What is the significance of single-mode operation in VCSELs?
Single-mode operation mitigates modal dispersion, extending the transmission distance in VCSEL-MMF optical interconnects.
What are the key design features of the VCSEL for high-speed performance?
The VCSEL uses a double mesa structure and benzocyclobutene (BCB) for improved thermal management, along with a gain-to-etalon wavelength detuning of approximately -15 nm.
What is the potential application of this high-speed VCSEL?
It has potential application in cryogenic optical interconnects for cryogenic computing, as well as in data center optical interconnects.
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