Millimeter-wave signal generation device based on difference frequency generation in a LiTaO3 rectangular waveguide
We have proposed a new DFG-based signal generation device in a LiTaO3 rectangular waveguide. 15 GHz signal was successfully generated from the fabricated device. In this paper, its application for higher-frequency signal generation is discussed.
Generation of continuous-wave millimeter-wave signals in a nonlinear lithium niobate optical waveguide
We demonstrate the generation of cw millimeter-wave signals in LN optical channel waveguides using optical technology. The spectral linewidth of the generated millimeter-wave signals is 2 kHz. The power of the measured cw millimeter-wave signals is almost in proportion to the power multiplication of two input optical signals. In this experiment, the frequency difference of two optical signals is 10 to 40 GHz, and the power of millimeter-wave signals showed variation within 4 dBm.
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.