A single Fabry-Perot cavity with two input beams (1064/IR and 532
nm/G) and a moveable end mirror.

The input mirror transmissivity (T1) and input power can be tuned for each
wavelength independently to create an optical trap i.e. an optical
spring with restoring force and damping.

The first figure gives the transfer function of the end mirror in
metres/Newton. The second figure displays the optical spring constants
associated with each input beam and their sum (the total optical
spring).


Interesting parameters to explore are:

1. Zero detuning for both beams. No springs. Recovers the mechanical
transfer function of the ETM.

2. Equal and opposite detunings for each beam, T1IR=T1G, PG/PIR=0.5
(linewidth is the same in frequency but there is a factor of two when
converting to metres). Optical springs cancel.

3. IR detuning = 2, G detuning = -0.5, PG/PIR = 0.1,
T1IR=T1G=0.0008. Stable spring same T1.
	   
4. IR detuning = 1.7, G detuning = -0.14, PG/PIR = 1, T1IR=0.0008,
T1G=0.0013. Stable spring same P.

5. IR detuning = -0.5, G detuning = 0.5, PG/PIR = 2.5, T1IR=0.001,
T1G=0.002. Stable spring same det.

-John