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1.55 μm photomixer LO sources operating at cryogenic temperatures for heterodyne mm-wave receivers

Authors:
J. E. J. Warner, B. Alderman, P. G. Huggard, B. N. Ellison
Abstract:
Photomixing is a flexible and efficient method of providing the local oscillator input to mm-wave heterodyne receivers. Photodiode based photomixers have conventionally been characterised at room temperature, but for use with superconducting mixers for astronomy it is desirable to locate and operate them in a cryogenic environment close to the superconductor-insulator-superconductor junction. We have thus investigated the effects of cooling W-Band waveguide photomixers based upon 70 GHz bandwidth, [lambda] = 1.55 µm, photodiodes from u2t Photonics AG. Operation is maintained to ambient temperatures below 30 K, and optical to mm-wave power conversion efficiency is found to increase upon cooling. In contrast to 300 K operation, the photocurrent is found to depend strongly with reverse bias, Fig. 1, although the (photocurrent)2 dependence of output power is maintained. Maximum detected mm-wave powers are of are order 100 µW at 85 GHz, and have been limited by the capability of the bias current supply. Temperature cycling the photomixer to 300 K was found to restore the original room temperature photoresponse.
Categories:
Sources
Year:
2005
Session:
2
Full-text:
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Page Number(s):
24