Light splitter and optical transmitter configuration with a light splitter

#The present invention relates to light splitters as well as optical transmitter configuration with a light splitter.

#The present invention is based on problems such as were recognized when employing X-cubes and will be explained in the following. But the findings can, in principle, be transferred to optical light splitters which, as will yet be explained, are used in connection with light of different polarization. Regarding this topic, reference can be made to A. Thelen, “Nonpolarizing interference films inside a glass cube”, Appl. Optics, Vol. 15, No. 12, December 1976.

#For example, in DE 40 33 842 a cuboid optical structural component composed of single prisms with dichroic layers is referred to as a “dichroic prism”. WO98/20383 by the sage applicant.

#FIG. 1 is a schematic optical transmission configuration of an X-cube,

#FIG. 2 illustrates conditions occurring when replacing conventional light valves,

#FIGS. 3, 4, 5, 6 and 7 are each graphs plotting reflectants or intensity of light against wavelength.

#The results presented in the following in conjunction with FIGS. 8 to 12, were measured using a configuration such as is represented in principle in FIG. 2. An X-cube was provided with color-selective coating systems 5 or 7, respectively. The material with the higher refractive index in the coating systems 5, 7 was TiO2, the material with the lower refractive index was a mixed material comprising SiO2 and TiO2 in a mixing ratio of ASiO2/ATiO2=60/40. The body of the X-cube comprised quartz glass.

#The effects of the transmission, resulting in the reflection measurements on the particular noninvolved coating system—thus for blue light the red-selective system 7 and for red light the blue-selective system 5—in particular the transmission difference for S and P-polarized red or blue light, respectively, were negligible.

#On the configuration of FIG. 2, in analogy to FIG. 3, in an X-cube with TiO2 as the material with the higher refractive index and SiO2 as the material with the lower refractive index on the light splitter according to the invention, were measured spectra for reflected blue light B in S- and P-polarization, represented in FIG. 8, and analogously for red light R in FIG. 9. The refractive index NLS within the range