Influence of the temporal fluctuations phenomena on the ECB LCoS performance

Liquid Crystal Displays (LCD) technology has shown to be very useful in numerous optical applications because of its capability to work as Spatial Light Modulators (SLM). The Liquid Crystal on Silicon (LCoS) displays are reflective LCDs that, because of the double pass of the incident beam through the device, give higher phase modulation than transmission LCDs with the same thickness of the LC layer. In recent works, we have thoroughly analyzed the response of a twisted nematic LCoS display working in normal incidence and we have detected that the kind of electrical signal addressed to our display produces fluctuations as a function of time of the LCoS display molecules optical axis orientation. Moreover, the temporal fluctuations produce two different physical effects that can adversely affect in optical applications. On one hand, the molecules fluctuations may produce changes at the reflected state of polarization as a function of time, introducing certain amount of effective depolarization. On the other hand, it has been demonstrated that the molecules fluctuations produce phase fluctuations that may affect the efficiency of diffractive optics elements. Here, we have characterized an Electrically Controlled Birrefrigence (ECB) LCoS display that allows us to manipulate the electrical signal addressed to it. Then, by selecting the appropriate electrical signal we can increase or decrease the fluctuation phenomena. Therefore, we have performed a polarimetric study of our (ECB) LCoS, analyzing its response dependence with different electrical addressed signals and taking special attention to the depolarization and retardance response of our device.