The optical theory of Fabry-Perot interferometers (FPIs) for x rays using dynamically diffracting thin perfect crystals as reflectors is developed. Application to a device using high diffraction orders in silicon crystals of thickness of the order of 100 μm or more shows that energy resolutions of the order of a tenth of a meV are achievable. The effect that various features, such as gap and mirror thickness, lattice mismatches, etc., have on the FPI resonances is studied.

We report on the optoelectronic (OE) mixing characteristics of a Schottky-enhanced InGaAs-based metal–semiconductor–metal photodetector (MSM–PD). The measured frequency bandwidth of such a mixer is less than that of a corresponding photodetector. The mixing efficiency depends on the light modulation, local oscillator, and mixed signal frequencies and decreases nonlinearly with decrease in optical power. This is not observed in GaAs-based and non-Schottky-enhanced InGaAs MSM–PDs. We present a circuit model of the OE mixer to explain the experimental results.

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Translational Doppler detection using a direct‐detect, chirped, amplitude‐modulated LADAR is demonstrated. A nonoptically coherent system is utilized to lower the target‐induced Doppler shift to tens of Hz, as opposed to several hundreds of megahertz for a coherent LADAR design. The Doppler shift is imposed on both the laser carrier and the intensity modulation impressed on the laser carrier. The data indicate that the LADAR is able to measure the Doppler shift due to the translational motion of a moving target. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 358–363, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20469

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