The laser absorption spectrometer approach offers the potential to provide the high-accuracy carbon dioxide mixing ratio measurements with the vertical and horizontal spatial resolution that is desired by the carbon cycle research community. It is generally agreed that 2.05 micron wavelength absorption band of carbon dioxide can offer good differential absorption optical depth. An amplifier with output power of 15W is needed to burst the output power for airborne and space applications. We propose to develop a high average power polarization maintaining single frequency Ho-doped 2.05 micron wavelength fiber amplifier with output power of 15W by developing innovative radiation hardened Ho/Tm-co-doped silicate glass fiber. In Phase I we will demonstrate radiation hardened Ho/Tm co-doped silicate glass fibers, and PM fiber amplifier with greater than 10W output power.