Detector Arrays for Digital Holographic Storage Applications

This chapter discusses detectors for holographic data storage applications. While it may be possible to use a single detector or linear array of detectors, the focus here is on 2-D arrays of pixels. There are many considerations for the detector array when designing a complete system that arise from the intimate relationship between the holographic storage system, optical readout technique, and the sensor pixels. The chapter begins with a discussion of these considerations, based on the assumption that commercially viable digital holographic data storage (DHDS) systems must be “smaller than a breadbox,” be affordable, have data capacities in the hundreds of gigabytes arena, and have readout rates in the regime of hundreds of megabytes per second. Today there are two primary technology choices for realization of the sensor array: charge-coupled devices (CCDs) and CMOS (complementary metal-oxide-semiconductor) active pixel sensors (APS). Both will be introduced and their relative merits presented [1–6]. In fact the CMOS APS, a much newer technology, will be shown to offer significant advantages over its predecessor, the CCD, when applied to digital holographic data storage systems. An example of a recently-fabricated CMOS APS for use in a DHDS is shown in Fig. 1.