Large calcium fluoride (CaF2) single crystals are required for the fabrication of lenses in so‐called wafer‐steppers of future IC‐lithography technologies operating at 193 nm and 157 nm. Numerical simulation plays an important role to design an adequate growth setup and processing conditions for the growth of high quality crystals. An important issue is the consideration of the internal heat transfer by radiation in the semitransparent CaF2 during the crystal growth process. Results of the numerical modeling of the heat transport are presented, which are obtained by using the software package CrysVUn++ with different models considering the internal heat transport in CaF2. To improve the availability of experimental data on CaF2 bulk growth, an especially designed R&D‐facility was built. This growth system is equipped with a variety of in‐situ measurement systems to detect the temperature distributions in the crystal and melt region. Calculated temperature distributions are compared with experimental data. Also first results on single crystal growth will be reported.
We demonstrate a novel and simple smart pixel which combines free space optics for the input signal and waveguide configuration for the output beam. Our monolithic smart pixels consist of a threshold switch with high photoconductive gain and a Franz–Keldysh waveguide modulator. The switch provides sufficiently high current to control directly the output beam via the modulator. A high switching contrast of ≳17 dB and a fan-out ≳230 at an optical output power of ≳130 μW has been achieved with our first monolithic smart pixels, which are still far from being optimized.
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