The current status of Photon Calibrator in KAGRA Bin-Hua Hsieh On - - PowerPoint PPT Presentation

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The current status of Photon Calibrator in KAGRA Bin-Hua Hsieh On - - PowerPoint PPT Presentation

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The current status of Photon Calibrator in KAGRA Bin-Hua Hsieh On behalf of Calibration group ICRR, The University of Tokyo Feb. 23 rd , 2018 2018 ICRR Thesis Workshop @ ICRR 1 Outline Overview Instruments of Photon Calibrator

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SLIDE 1

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

The current status of Photon Calibrator in KAGRA

Bin-Hua Hsieh On behalf of Calibration group

1

ICRR, The University of Tokyo

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SLIDE 2

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Outline

  • Overview
  • Instruments of Photon Calibrator
  • Requirements
  • Optical Follower Servo and feedback loop
  • Measurement plan
  • Results
  • Summary

2

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SLIDE 3

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018
  • LIGO and Virgo have already detected gravitational wave,

we need the calibration to extract parameters accurately from gravitational wave signal.

3

Why Calibration is important?

Goal of accuracy

  • 1% in amplitude
  • 1 degree in phase
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SLIDE 4

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Why we need Photon Calibrator?

4

  • 1. Characterize the displacement of

mirror

  • 2. Understand the parameter in

realtime interferometer control in

  • rder to reconstruct the

gravitational wave signal.

Laser Tx Rx Tx Rx

displacement

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SLIDE 5

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

ETM: End Test Mass Photodetector Beam Splitter

Pcal: Photon Calibrator PCal

Laser

ETM

Tx Rx Tx Rx

EXA EYA

5

Where is Photon Calibrator in KAGRA?

3km 36m

Tx

Transmitter module

Rx

Receiver module

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SLIDE 6

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

6

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SLIDE 7

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Transmitter Module

OFSPD OFSPD

7

900m m 900mm

20W

2 innovations compared to LIGO:

  • 1. 20 watts high power laser
  • 2. 2 Acousic optic modulator
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SLIDE 8

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Receiver Module

8

RxPD QPD

Integrating sphere at Rx Quadrant Photo Diode: Monitoring the beam position

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SLIDE 9

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Relative Power Noise Requirements

9 Force

Force to length transfer function strain sensitivity curve of KAGRA

∆L(f) = 2∆P cos(θ) c 1 M(2πf)2 < 1 10∆h(f)L

RPN = ∆P P = Mc(2πf)2∆h(f)L 20P cos(θ)

M: ETM Mass (23kg) c: Speed of light L: Arm length of Interferometer (3km) P: Laser Power (10W)

Frequency(Hz) 10

2

10

3

10 ) Hz Sensitivity(1/

24 −

10

23 −

10

22 −

10

21 −

10

20 −

10

19 −

10

KAGRA strain sensitivity

Frequency(Hz) 10

2

10

3

10 ) Hz Magnitude(dB RPN/ 140 − 120 − 100 − 80 − 60 − 40 − 20 −

Pcal requirement

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SLIDE 10

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Calibration Lines

10

Frequency(Hz) 10

2

10

3

10 ) Hz Magnitude(dB/ 140 − 120 − 100 − 80 − 60 − 40 − 20 −

OFS 1 OFS 2

7Hz 35Hz 330Hz 1kHz 3kHz

Preliminary

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SLIDE 11

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Harmonic Noise Requirements

11

FFT

35Hz modulation

To decide whether the peak is within requirements or not, first we need to define the noise requirement of Photon Calibrator.

70Hz 35Hz 105Hz 140Hz

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SLIDE 12

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

12

Mirror

Injected Signal

OFS AOM

Power stabilization

PD

  • 1

Laser Offset Gain

We use Optical Follower Servo and photodetector to make a closed-loop in order to reduce the noise of laser.

Optical Follower Servo OFS AOM Acoustic Optic Modulator PD Photodetector

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SLIDE 13

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Optical Follower Servo

OFS Front Board

  • Ver. 4

OFS Back Board

  • Ver. 1

13

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SLIDE 14

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

OFS & Interface Chassis

OFS Chassis Back Board

14

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SLIDE 15

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Measurement Plan

15

Lab test: KEK

Kamioka test: KAGRA site

  • Develop Photon Calibrator
  • Measurement:
  • 1. Transfer function
  • 2. Relative Power Noise
  • 3. Higher Harmonic Noise
  • 4. Peak stability
  • Assemble Photon Calibrator
  • Measurement:
  • 1. Transfer function
  • 2. Relative Power Noise
  • 3. Higher Harmonic Noise
  • 4. Peak stability

Ｗe are here!

Analysis is still ongoing

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SLIDE 16

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

16

Tx module Rx module OFS & Interface module Laser From/To DGS Laser beam Lab test in KEK

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SLIDE 17

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

17

Tx module Rx module OFS & Interface module Lab test in KEK

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SLIDE 18

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

18

Bin-Hua Hsieh Yu-Kuang Chu (Cory) Takaaki Yokozawa Takayuki Tomaru Sadakazu Haino Yuki Inoue Takahiro Yamamoto Nobuyuki Kanda

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SLIDE 19

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

19

OFS AOM

Gain budget diagram

PD Laser 31.808dB

OFS1:56.91dB OFS2:56.07dB

Open-loop TF

Beam Sampler 0.004 NDF 2.3OD =0.005 OFS AOM PD 31.808dB Beam Sampler 0.004 NDF 2.3OD =0.005 20.70 20.39 0.87 0.90 26.31dB 26.18dB

  • 1.21dB
  • 0.92dB

DAC

injected signal Gain Offset

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SLIDE 20

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Transfer function

Frequency(Hz) 10

2

10

3

10 Magnitude(dB) 10 20 30 40 50 60

Closed loop simulation Closed loop observed Open loop simulation Open loop observed

Simulation vs. Observed (amplitude)

Frequency(Hz) 10

2

10

3

10 Phase (degree) 80 − 70 − 60 − 50 − 40 − 30 − 20 − 10 −

Closed loop simulation Closed loop observed Open loop observed Open loop observed

Simulation vs. Observed (phase)

Gclosed = Gopen 1 + Gopen Observed results consist with simulation result.

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SLIDE 21

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Gclosed = Gopen 1 + Gopen Path 1 result consists with Path2 result.

Frequency(Hz) 10

2

10

3

10 Magnitude(dB) 1 − 0.8 − 0.6 − 0.4 − 0.2 − 0.2 0.4 0.6 0.8 1

Path1 Path2

Closed Loop (amplitude)

Frequency(Hz) 10

2

10

3

10 Phase (degree) 10 − 8 − 6 − 4 − 2 − 2 4 6 8 10

Path1 Path2

Closed Loop (phase)

Frequency(Hz) 10

2

10

3

10 Magnitude(dB) 50 51 52 53 54 55 56 57 58 59 60

Path1 Path2

Open Loop (amplitude)

Frequency(Hz) 10

2

10

3

10 Phase (degree) 80 − 70 − 60 − 50 − 40 − 30 − 20 − 10 −

Path1 Path2

Open Loop (phase)

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SLIDE 22

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Summary

22

  • We built a Photon Calibrator with 20W laser for the

reconstruction of gravitational wave.

  • We used Optical Follower Servo to make a closed-

loop feedback control in order to decrease the noise

  • f laser power.
  • We finished the lab test in KEK, and we are going to

move on to KAGRA site test.

  • The measurement results of transfer function consist

with simulation results, and each paths also consists with each other.

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SLIDE 23

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Future Plan

23

  • We are assembling Photon Calibrator and will characterize it in

KAGRA site.

  • We will measure the
  • transfer function,
  • relative power noise,
  • higher harmonic noise
  • peak stability

in KAGRA site, and compare the result with lab test.

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SLIDE 24

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Supplementary

24

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SLIDE 25

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

AOM transmittance

AOM transmittance divided by the peak value at 0.5V input

Input voltage (V) 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 Ratio to value at 0.5V (%) 10 20 30 40 50 60 70 80 90 100

Path1 Path2

AOM Transmittance

working point

working point: input voltage at 0.23V

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SLIDE 26

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

26

Setup

HPF 0.03Hz pole 100 gain

P = P0 + n P0 = P0

0 + n0 ≈ gn(P0 0 ≈ 0)

RPN = n P0 = n0 gP0

g = 100

In our measurement, P0 comes after PD. Therefore,

P’ OFS AOM PD Laser Beam Sampler NDF ADC P

DAC

injected signal Gain Offset

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SLIDE 27

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

DAC noise

  • I use spectrum analyzer and g=1000 (60dB) amplifier to

check the noise level of DAC. The noise level of DAC is -130Vrms/rtHz. In our measurement which DC signal of PD is around 3V, this DAC noise is around -140dB/rtHz.

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SLIDE 28

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Noise floor by changing Offset and Gain (Open loop)

  • I measured closed loop noise level and open loop noise

level of OFSPD1 with different gain and offset using spectrum analyzer.

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SLIDE 29

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Noise floor by changing Offset and Gain (Open loop)

To AOM(V) Gain (dB) OFS1 Offset OFS2 Offset OFS1 RPN OFS2 RPN 0.1 0.12 0.12

  • 108.73
  • 108.73

15.174 0.042 0.04

  • 97.73
  • 97.73

31.808 0.0288 0.0277

  • 77.73
  • 77.73

0.2 0.22 0.22

  • 112.6
  • 112.96

31.808 0.0314 0.0302

  • 87.6
  • 87.95

0.225 0.246 0.246

  • 114.13
  • 114.43

31.808 0.032 0.0308

  • 89.13
  • 89.43

0.3 0.325 0.32

  • 115.67
  • 115.67

31.808 0.0342 0.033

  • 92.67
  • 92.67

0.4 0.43 0.424

  • 114.82
  • 115.22

31.808 0.037 0.0356

  • 99.82
  • 100.22
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SLIDE 30

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Noise floor by changing Offset and Gain (Closed loop)

To AOM(V) Gain (dB) OFS1 Offset OFS2 Offset OFS1 RPN OFS2 RPN 0.1 31.808 0.8 0.8

  • 127.73
  • 127.73

0.2 31.808 2.5 2.6

  • 124.60
  • 124.96

0.225 31.808 3 3.1

  • 124.40
  • 124.71

0.3 31.808 4.3 4.5

  • 122.61
  • 122.87

0.4 31.808 5.5 5.8

  • 127.74
  • 125.19
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SLIDE 31

2018 ICRR Thesis Workshop @ ICRR

  • Feb. 23rd, 2018

Discussion

  • 1. From closed Loop measurement, change the offset

doesn’t effect the noise level too much.

  • 2. From open loop measurement, we can see that if the

gain increases, the noise also increases. If we decrease the gain in close loop measurement, then the noise level might decrease. Then we need to sacrifice the high gain in close loop feedback control.