Subwavelength diffractive features etched into a substrate lead to form birefringence that can produce polarization sensitive elements such as wave plates. Using etched features allows for the development of pixelated devices to be used in conjunction with focal plane arrays in polarimetric imaging systems. Form birefringence exhibits dispersion that can be advantageous to the design of wave plates with an achromatic response. Taking advantage of this dispersion, diffractive wave plates with good achromatic characteristics can be designed for the spectral region. Previous work in this area has produced good results over a subset of this wavelength band, but designing for this extended band is particularly challenging. The fabrication processes for the subwavelength features will be discussed and fabricated devices with a measured average phase retardation of and rms variation of will be presented.