ALMA Memo # 435

A Hybrid Option for the First LOs using Direct Photonic LO Driver

M. Ishiguro, Y. Sekimoto, A. Ueda, S. Iguchi, T. Noguchi (NAOJ)
J. M. Payne, L. R. D'Addario, W. Shillue (NRAO Tucson)

15/09/2002 

Keywords: Local Oscillator, Photomixer, Frontend

We propose a hybrid option for the first local oscillators (LOs) of ALMA 
in which a direct photonic LO driver is used to drive cold multipliers. 
The photomixer using NTT uni-travelling carrier photodiode has been demonstrated to have high power of 2 m W at 100 GHz and low amplitude noise of $< 7 - 17$ K/$\mu$W in the frequency range of $98 - 105$ GHz. This option simplifies the LO part of the cartridge in the baseline ALMA and retains a future possibility for a direct photonic option.