Multi-color infrared (IR) focal planes are highly desirable for next generation advanced IR systems for space and the missile defense applications. Multi-color focal plane arrays (FPA) in long wavelength that can operate at higher temperatures thanextrinsic silicon devices are needed to meet future space and missile defense applications.The objective of the proposed Phase I effort is to explore LW/LW, HgCdTe based focal plane arrays covering the spectral bands between 8-25 microns. To cover the spectral region, the device designs will be explored and modeled with either one or twodistinct HgCdTe based FPA's that can cover 8 to 14, 14-18, 18-22, and 22-25 micron bands. The trade-offs will be performed to evaluate the feasibility of building a single multi-color FPA or two distinct FPA covering the broad band for 8 to 25 microns.IR photo-detectors and FPA's are useful in a wide variety of industrial, military, and scientific applications where detection of IR radiation plays a role. Most of these applications for detection and/or measurement require high performance IR detectorseither as linear arrays or as two-dimensional arrays. The market for non-defense based IR photo-detectors is expected to grow rapidly over the next 10 years.Within the Department of Defense, there are several possible applications for IR FPA's in MWIR, LWIR and VLWIR bands. In addition to the boost phase missile detection applications, space sensors and tactical sensors / seekers, IR photo-detectors and FPA'scan be used in surveillance and IR detection applications.The characteristics that make multi-color IR photo-detectors suitable for defense applications also benefit many industrial and scientific applications. Several applications in environmental monitoring and control use IR sensors. For example, IR basedsystems can be used for chem.-bio detection. In addition, IR spectroscopy plays an important role in several medical and scientific applications.