High-precision alignment of optoelectronic devices for optical phase conjugation

Digital optical phase conjugation (DOPC) is considered as a promising solution to achieve optical focusing against scattering. The implementation of DOPC based on the digital micromirror device (DMD) has been proven to have great potential, supporting a large number of modulation modes and a high modulation rate. However, the accuracy of optical alignment seriously affects the focusing contrast, limiting the applications of DMD-based DOPC systems. Here we demonstrate a simple alignment protocol including a marker-assisted tuning and an embedded compensation. Our approach can realize an exact pixelwise optical conjugation between the DMD and detector, as well as a rapid compensation for aberrations and minor misalignment. Experimental results show that the proposed alignment protocol improves the focusing contrast to 66% of the highest value predicted in the theory.