Recently, a new large-aperture MEMS modulator has been introduced, bringing a new dawn to high-speed, energy-efficient optical communication systems.
Traditional MEMS optical modulators have a number of performance limitations. For example, micromirror-based modulators often only work at lower frequencies and are difficult to meet the needs of modern high-speed data transmission. Grating modulators, on the other hand, have some advantages, but they face the problems of bending distortion and unsatisfactory optical efficiency. In addition, the large aperture, which is essential for high-power optical communication systems, is also difficult to achieve due to mechanical limitations, which seriously restricts the development of optical communication systems.
Researchers from Northwestern Polytechnical University published their research results in the journal Microsystems & Nanoengineering, which provide innovative solutions to these problems. They developed a new MEMS encoder modulator that integrates a tunable sinusoidal grating with a wide-side confined continuous band to achieve a large aperture of 30×30mm. This dimensional breakthrough is significant, providing a wider space for the transmission of high-power optical signals.
With an optical efficiency of up to 90% and a dynamic modulation contrast ratio of more than 95%, this modulator shows great potential for applications in the field of free-space optical communications and remote sensing. In free-space optical communication, high optical efficiency means that the signal is less lost during long-distance transmission, which can ensure signal integrity and achieve more stable and high-speed data transmission. Its excellent modulation contrast can effectively distinguish between the "0" and "1" states of the signal, reducing the bit error rate and improving the communication quality.
In terms of modulation speed, the modulator supports high-speed modulation up to 250kHz with an extremely fast response time of nearly 1.1 microseconds. This feature makes it useful in areas such as light detection and ranging (LiDAR) and adaptive optics. In LiDAR systems, fast modulation speeds enable more accurate and faster detection and imaging of target objects, improving the safety of autonomous vehicles and the accuracy of industrial inspections. In the adaptive optics system, it can quickly adjust the optical signal, compensate for the optical wavefront distortion caused by atmospheric turbulence and other factors, and improve the performance of astronomical observation and laser communication.
Figure: Large aperture MEMS modulators: an innovative breakthrough in optical communications
The dispersive properties of modulators also open up new horizons for wavelength sensing applications. In spectrometers and hyperspectral imaging systems, it can accurately modulate and analyze different wavelengths of light, help researchers obtain more detailed spectral information, and play an important role in environmental monitoring, biomedicine, material analysis and other fields.
From the point of view of technological innovation, the design of the wide-side constrained continuous belt is exquisite. Not only does it avoid bending distortion, but it also allows for an expandable expansion of the aperture without affecting the resonant frequency of about 460.0kHz. The sinusoidal grating design maximizes the fill factor to 96.6% and significantly improves the diffraction efficiency, achieving a 20dB extinction ratio and 98% modulation contrast at 100kHz. A through-hole array on the surface of the grating optimizes air damping, allowing the modulator to achieve a critical damping response, eliminating residual oscillations and further improving modulation performance.
The modulator's silicon-on-insulator (SOI) process ensures a reliable manufacturing process, laying the foundation for large-scale production. This means that in the future, the modulator is expected to be mass-produced at a lower cost, accelerating its wide range of applications in various fields.
As the study's corresponding author, Dr. Yongqian Li, highlighted, the modulator combines a scalable aperture design with superior optical efficiency, opening up new possibilities for high-power, high-speed applications ranging from LiDAR to next-generation communication networks. It eliminates the micromirror structure, reduces system complexity and cost, and makes this technology easier to apply on a large scale.
Going forward, this large-aperture MEMS modulator is expected to be further upgraded as technology continues to advance. For example, the multi-channel beam shaping function can be implemented to transmit more data at the same time and improve the capacity of the communication system. It is integrated with the quantum communication system to provide more efficient modulation means for the development of quantum communication, and promote the quantum communication technology from theoretical research to practical application.
