Overview

• A set of phase modulation sidebands are imposed to the main laser beam for control of the mode cleaner cavity and the main interferometer. The frequency of the sidebands are determined from the signal extraction and control scheme: 11MHz, 23.5MHz, and 55MHz.
• We are investigating a multiply resonant circuit to be attached to EOM in order to create those three pairs of sidebands with a single crystal.
• (What is motivation? Why single crystal? Why three eoms are not enough? Why triple electrode EOM is not enough?)

• The feasibility and the basic ideas of the triple resonant circuit was investigated by Stephanie Erickson, a 40m SURF student in 2009 Summer. Link to Stephanie's descriptions (What did she demonstrated?)

Steps for Development

• studying the principle of LC circuit + transformer

• investigation of loss effect in LC circuit

• make a test circuit (single resonant) with highest impedance ( - Dec.20)
• make a new transformer for matching the impedance of the test circuit ( - Dec. 25)
• performance test by using optical spectrum analyzer ( - Dec. 31)
• study of triple resonant circuit (- Jan.5)
• investigation of loss effect in the multi-resonant circuit ( - Jan.12)
• make a prototype circuit with highest impedance ( - Jan.13)
• make a new transformer for prototype ( - Jan. 20)
• performance test of prototype by optical analyzer ( - Jan. 25)
• final design and ordering (- Jan.31)
• performance test with ordered circuit
• installation

1. Conceptual design .

2. Transformer

• The reason why we use a transformer are mainly follower;

• step up the voltage,

• impedance matching.

• In order to make a high efficient circuit, big number of step-up gain is required.
• The figure shows the equivalent circuit of transformer.

3. Loss ~ to make high impedance~

App. impedance measurement