Dynamically tunable transmissive color filters using ultra-thin phase change materials.

Qiang He,Zengguang Cheng,Nathan Youngblood,Harish Bhaskaran,Xiangshui Miao

doi:10.1364/oe.411874

Abstract

Structural color filters (i.e. plasmonics and nano-cavities) provide vivid and robust color filtering in applications such as CMOS image sensors but lack simplicity in fabrication and dynamic tuning. Here we report a dynamically tunable, transmissive color filter by incorporating an ultra-thin phase change layer inside a thin-film optical resonator. The transmitted color spectrum can be designed over the entire visible range and shifted by around 50 nm after phase transition. Angle dependence shows little color variation within a ±30° viewing angle. Crucially, only film deposition is required to fabricate our phase change color filter, showing great potential for large-scale and inexpensive production. The dynamically tunable color filter, described in this paper, could be a promising component in display, CMOS sensor, and solar cell technology.

Highlights

Color filters (CFs), either transmissive or reflective, have been regarded as vital components in CMOS image sensors, smart windows, solar-cells and nano-display applications [1,2,3,4]
We present a lithography free active color filter based on a incorporating a phase change material within an optical cavity
The color filters, which consist of a resonant cavity covered by an optimized anti-reflection coating (ARC), are designed on a transparent glass substrate

Summary

Introduction

Color filters (CFs), either transmissive or reflective, have been regarded as vital components in CMOS image sensors, smart windows, solar-cells and nano-display applications [1,2,3,4]. The wideband dynamic tuning of the transmissive light across the entire visible spectrum remains challenging, recent progresses have been obtained in the active reflective display featuring low energy operation and high resolution by our previous work [11,12] and others [13,14]. Previous work has shown the first GST-based reflective display device utilizing an optoelectronic framework with low-dimensional phase change layer [11], enabling higher resolution, faster switching and lower power consumption. Dynamically tunable transmissive color filters based on phase change materials have so far not been demonstrated Such filters are potentially useful for creating active pixels for imaging devices such as CMOS image sensors, which can be readily modulated across the entire visible wavelength at high speeds. Our color filters do not require any complicated lithographic methods during fabrication, which greatly reduces the cost and complexity of our device

Results and discussion

Conclusion

Experimental section