Low Power Compact 3D-Constructed AlScN Piezoelectric MEMS Mirrors for Various Scanning Strategies

Abstract

In this paper, the newly developed 3D-constructed AlScN piezoelectric MEMS mirror is presented. This paper describes the structure and driving mechanism of the proposed mirror device, covering its driving characteristics in both quasi-static and resonant scan modes. Particularly, this paper deals with various achievable scan patterns including 1D line scan and 2D area scan capabilities and driving methods to realize each scanning strategy. Bidirectional quasi-static actuation along horizontal, vertical, and diagonal scanning directions was experimentally characterized and even under a low voltage level of ±20 V, a total optical scan angle of 10.4° was achieved. In addition, 1D line scanning methods using both resonant and non-resonant frequencies were included and a total optical scan angle of 14° was obtained with 100 mVpp under out-of-phase actuation condition. Furthermore, 2D scan patterns including Lissajous, circular and spiral, and raster scans were realized. Diverse scan patterns were realized with the presented AlScN-based MEMS mirror device even under a low level of applied voltage. Further experiments using high voltage up to ±120 V to achieve an enhanced quasi-static scan angle of more than 20° are ongoing to ensure repeatability. This multi-functional MEMS mirror possesses the potential to implement multiple scanning strategies suitable for various application purposes.

Low-power multi-scan patterns capable 3D-constructed piezoelectric MEMS mirrors

“…The mirror devices consist of total four piezo actuators (Q1 to Q4), and each electrode is separated allowing for individual drive control. Available piezoelectric materials are AlN and AlScN which are competitive piezoelectric thin film materials showcasing linear response, bipolar actuation, and complementary metaloxide-semiconductor (CMOS) compatible with batch fabrication capabilities [15][16]. Two different poly Si thicknesses of 15 μm and 50 μm are currently available.…”

“…When the thickness of the structural layer and thus the piezo actuator cantilever is 15 μm, improved quasi-static characteristics can be expected. The detailed analysis of AlScN MEMS mirrors is presented in [15]. Table 1.…”

“…Previously, the development of the mirror device was primarily focused on increasing mirror diameter, scan angle, or resonant frequency. The detailed content dealing with changes in mirror design specifications is presented in [15]. The trend has shifted towards application-oriented goals, with a specific focus on determining the most effective scanning strategies and optimizing scan patterns.…”

Biaxial resonant MEMS mirrors with large field of view for LiDAR systems

“…The vacuum-encapsulated MEMS mirrors of Design 1 and 2 have been characterized experimentally with a home-built optical set up, which has been described in detail in Ref. 11 The piezoelectric layers were electrically driven by a sinusoidal voltage, generated by a conventional function generator (Agilent 33500B, Keysight) and 20X-Falco systems amplifiers. Here, only half of the piezoelectric layers were actuated electrically, since the other piezoelectric layers were used for the sensing of the mirror position (cf.…”