Polarization Image Sensor for Highly Sensitive Polarization Modulation Imaging Based on Stacked Polarizers

Abstract

In this article, We demonstrated an image sensor for detecting changes in polarization with high sensitivity. For this purpose, we constructed an optical system with a two-layer structure, comprising an external polarizer and polarizers on a pixel array. An external polarizer is used to enhance the polarization rotation while reducing the intensity to avoid pixel saturation of the image sensor. Using a two-layer structure, the two polarizers can be arranged under optimal conditions and the image sensor can achieve high polarization-change detection performance. We fabricated the polarization image sensor using a 0.35-µm CMOS process and, by averaging 50 × 50 pixels and 96 frames, achieved a polarization rotation detection limit of 5.2 × 10 −4 • at a wavelength of 625 nm. We also demonstrated the applicability of electric-field distribution imaging using an electrooptic crystal (ZnTe) for weak-polarization-change distribution measurements.

THz near-field intensity distribution imaging in the 0.3 THz band using a highly sensitive polarization CMOS image sensor using a 0.35 μm CMOS process

“…5. [15][16][17] In general, the photodiodes of image sensors are small; thus, they are not suitable for detecting weak polarization changes owing to their low upper limit of incident light intensity. Furthermore, the extinction ratio of on-pixel polarizers fabricated on polarization image sensors is lower than that of uniform polarizers because polarizers with different polarization angles are arranged at each pixel.…”

Improvement of on-pixel polarizer with 0.35 μm CMOS process for electro-optic imaging systems

“…The proposed system has a double-polarizer structure composed of signal-selective and on-pixel-analyzing polarizers. 27,28) The image sensor was fabricated using a standard CMOS process based on Si. A light source with a wavelength of 780 nm was selected, which is detectable using Si photodiodes.…”

“…In our previous work, the sensitivity of the system was sufficiently high to enable electric-field measurements even with a 0.35 μm standard CMOS process. 27,28) The extinction ratio enables polarization-separation performance in the polarizers. Obtaining a high extinction ratio with an on-pixel polarizer is more difficult compared to a uniform polarizer.…”

“…The extinction ratio of on-pixel polarizers at 780 nm was only 1.5, and there remains much room to improve the performance of the electric-field imaging system. 27,28) In this study, we compared the characteristics of on-pixel polarizers based on their structure. Additionally, we presented an enhancement in the extinction ratio by multilayering the polarizers.…”

Polarization Reversal of Group IV–VI Semiconductors with Pucker‐Like Structure: Mechanism Dissecting and Function Demonstration

“…[10][11][12][13] However, despite the notable advantages of polarization imaging mentioned above, it still faces some limitations in further miniaturizing the sensor footprint and the implementation of image enhancement. For instance, achieving the recognition of band information of imaged objects and implementing image enhancement based on polarization imaging remains challenging, requiring the use of spectrometers or other components, [14] thereby increasing the complexity of the image processing system and hindering the trend of miniaturization. To overcome these limitations, future developments in polarizationsensitive image sensors need to focus on scaling down the footprint, improving the versatility and flexibility of imaging systems, as well as optimizing image processing algorithms.…”