Link to Relevant documents
- As of April 2019
Official reviews
March 2018 Material by Yokogawa et al.,
August 2017 Material by Kambara et al.,
Past Considerations (mostly back in 2012)
Auxiliary Lock System
Also known as green laser lock, this scheme will make use of auxiliary lasers to lock the arm cavities first.
Servo simulation
Optical Table Layout
Purchase List
SVN archive
Oscillator phase noise requirement for PLL local oscillator
See here.
Overview of Green Lock Scheme
Lock procedure
Block diagram
Description of the blocks
Phase Comparison
When you combine two beams with power P, we get the beat note with amplitude of 2 alpha P Sin phi, where alpha is the contrast (0~1) and phi is the relative phase between the fields. Thus, the phase sensitivity is 2 alpha P [W/rad]. e.g. Two 1mW beams geneartes 4mWpp beat if the contrast is 1. The slope is 0.002 alpha W/rad.
For the broadband PD, InGaAs is not relevant because of the high junction capacitance. If we use Si PD (like FFD-100 phi=2.5mm), the responsivity is eta = 0.08 [A/W].
- BBPD Transimepedance and the shotnoise intercept current are assumed to be 1e3 [V/A] and 0.3 [mA], from the experience of LIGO BBPD.
Total gain is 1 [V/rad] if we assume alpha and P to be 0.5 and 12.5mW respectively.
- Shot noise
Shot noise of the modulated beam is described by <in^2> = 2 e [I0+1/2 dI Sin(phi)], according to N. Mio and K. Tsubono, Physics LettersA 164 (1992) 255-258.　Does nonstationary part cancel because of the orthogonality of the RF and LO signals???
- Consider only the stationary part, in = sqrt(2 e I0). Thus in/eta/(2 alpha P) = sqrt(e / eta / alpha / P) [rad/rtHz]. This corresponds to 2.5e-8 rad/rtHz.
Frequency noise of NPRO
- 1e4/f [Hz/rtHz] according to R. Adhikari's PhD thesis.
