Cascade Multi-Degree-of-Freedom Electromagnetic Micro-Grating: Achieving Amplified Scanning Angle Without Sacrificing Linearity

Micro-gratings have become pivotal components in advanced optical systems, offering precise light manipulation and analysis. However, achieving a high spectral resolution and enlarged scanning angles without sacrificing linearity remains a challenging endeavor. This article presents an electromagnetically driven micro-grating designed to address these challenges. To achieve these enhancements, our work employs a multi-degree-of-freedom resonator design that comprises a grating, an actuator coil frame, an integrated angle sensor, and four cantilever torsion springs. The scanning angle amplification effect is realized by optimizing the multiple-input-multiple-output (MIMO) behavior associated with the system’s second-order harmonic. With the amplification effect of the scanning angle, a minor displacement in the actuator coil frame can achieve a significant scanning angle on the grating. A theoretical model of the proposed multi-degree-of-freedom design has been established together with a finite-element simulation model. The potential optimization parameters have been analyzed and discussed in detail. We fabricated a demonstrator based on Flame-Retardant-4 material, and the experimental results showed that the device with mirror size
$12\times 12$
mm could reach a 6.94° scanning angle with a 75-mArms drive current. The amplification ratio of 1.84 (drive coil 3.77°) could be observed aligning well with the harmonic simulation’s prediction. Also, the micro-grating exhibits excellent linearity with a correlation coefficient of 0.99979.