MIF's Interface with IOO

Carrier

iKAGRA

Wavelength

1064nm

Comment

Power

>500mW at PRM AR

Polarization

S

Complex beam radius at the PRM AR

9.8358048093144834+i*18.307397678406861

So called q-parameter in the unit of m. Although there is no PRM in iKAGRA, this is a beam parameter at the position where the AR surface of the PRM will be located in bKAGRA. This parameter gives the perfect mode match to the iKAGRA arm cavities. However, the MIF does not require IOO to provide 100% mode matching in iKAGRA phase.

Frequency Noise

To be calculated from the viewpoint of lock acquisition.

Residual frequency noise after the MC.

Relative Intensity Noise

To be calculated from the viewpoint of lock acquisition.

Beam Jitter

1e-6 rad RMS

Calculated by requiring that beam spot moves less than 1mm after traveling 3km.

bKAGRA

Wavelength

1064nm

Comment

Power

75W at PRM AR

Polarization

S

Complex beam radius at the PRM AR

-10.580258464886768+i*56.648923633432595

So called q-parameter in the unit of m.

Frequency Noise

BRSE, DRSE

Residual frequency noise after the MC. For more detailed discussion, see this.

Relative Intensity Noise

BRSE, DRSE

Beam Jitter

3e-11 rad/rtHz@10Hz, 7e-14 rad/rtHz@100Hz (Safety mergin of 20)

Detail

Modulations

iKAGRA

Name

Freqency

Type

Mod. index

Relative Amplitude to Carrier before PRM

Comment

f1

16.880961MHz

PM

0.1rad

bKAGRA

Name

Frequency

Type

Mod. index

Relative Amplitude to Carrier before PRM

Oscillator Phase Noise

Oscillator Amplitude Noise

Comment

f1

16.880961MHz

PM

0.15rad

BRSE, DRSE

BRSE, DRSE

f2

45.0159MHz

PM

0.05rad

f3

56.2699MHz

AM

0.05rad

Non-resonant sidebands to be used only for lock acquisition.

Assumed modulator arrangement

In the Optickle modeling, f1, f2 and f3 modulations are applied in series in this order. Optickle can properly handle the generation of sidebands on sidebands. So it is confirmed that series modulation is OK for bKAGRA. In practice, it may be better to apply f3 modulation first. This is to be discussed with IOO.

RFSB transmission servo

The RFSB frequencies (f1 and f2) should be set to maximize their power inside PRC, i.e. fully resonant in the central part of the interferometer. Therefore, at first, the MC length has to be adjusted to transmit the RFSBs optimized in frequency for the main interferometer. After the DC adjustment, however, small continuous adjustment to the RFSB frequencies to minimize the RFAM generation by the transmission through the MC should be performed by a RFSB transmission servo.