Re: Help with adjustment of a New Focus Electro-optic Modulator

What are you driving it with?
I am driving it with a microwave oscillator (fixed frequency 9.2 GHz)
+ power oscillator (up to 2 Watts). At the output of the power
amplifier, a circulator is mounted to deliver the signal to the EOM and
monitor the reflected signal with a power meter. The adjustement knob
of the EOM is tuned to the resonant frequency of the oscillator (the
reflected power is > 20 dB below the power delivered to the EOM). I
tried to drive the EOM up to 2 watts without observing any sidebands.

What is the FWHM of your Fabry-Perot?
The FWHM is around 100 MHz.

Is the Fabry-Perot tuned properly? Is the beam mode-matched with
the F-P?

it's property tuned since all transversal modes are supressed. Using
another laser diode, I set its frequency 9.2 GHz higher than the
frequency of the first laser diode (I look at the mixing signal in a
photodetector with an spectrum analyser), so that I can observe both
peaks in the FP. By this method I can estimate the position in The FP
where I expect one sideband.

About the beam entering the EOM, its diameter is 1/3 of the smallest
EOM aperture dimensions and its polarization is horizontal (as the
manufacturer requires). The EOM is mounted on a 4 axis tilt aligner.
What is your experience adjusting the EOM? Is it really so tricky?

.

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