VIRGO_LCGT MeetingLaser & Mirror

5 November, 2010

Norikatsu Mio

Laser MC1

MC2

MC3PRM PR1

PR2

BS

SR2

SR1

SRM

ITMX

ITMY

ETMX

ETMY

MT1

MT2

Schematic View of LCGT Optical System

780 W

75 W150 W

EOMFI

PD

PZT

Nd:YAG rod

Nd:YAG NPRO

quartz rotator

2W100W

BW

FI

QWP

PBS

WB-EOM

Intensity stabilization（ Injection Current Contro

l ）

150W

Frequency Stabilization

f < 10 kHzPZT, Crystal Temp.

10 kHz < f < 1 MHzWB-EOM

Injection Locked laserMaster: 2-W NPROSlave: Mitsubishi

Power Amplifier

High-Power Laser Modules

Mitsubishi

Laser for LCGT

Laser• Basic design has been tested with a prototype

laser.• Discussion with Mitsubishi that makes laser

modules for LCGT.– We will buy laser modules from Mitsubishi and

assemble a laser system from them by ourselves or by another company.

• Alternative choice?– Commercial fiber laser: 40W

Alternative design

Mitsubishi laser modules

Fiber laser amplifiers

NPRO(500mW)

40 W

40 W

80 W

200 W

Laser MC1

MC2

MC3PRM PR1

PR2BS

SR2

SR1

SRM

ITMX

ITMY

ETMX

ETMY

MT1

MT2

Size of these mirrors must be determined according to the design policy of the interferometer.

38cm

10cm

Mirrors for LCGT

Mirrors for Main cavitiesInitial: Silica

Final: Sapphire

Mirror

• Size of the mirrors for main cavities was determined as 25cm x t10cm in order to make full use of the iLIGO mirror substrates.

• Size of the beam splitter is 38cm x t12cm. The substrate will be prepared within this year.

• Concerning polishing and coating, several companies inquired the situations.

• We need to develop a new coating machine for large mirrors. Some Japanese companies may collaborate with us; this issue is under consideration.

• Polish: Collaboration with Riken Group– Details are not fixed.

Current Plan• For iLCGT, the size of the mirrors is chosen as that of iLIGO’s mirror.• BS and ITMs will be newly fabricated from Japanese Silica.

Laser MC1

MC2

MC3PRM PR1

PR2BS

SR2

SR1

SRM

ITMX

ITMY

ETMX

ETMY

MT1

MT2

LIGO mirrors(re-polishing and re-coating)25cm x t10cm

38cm x t12cm

10cm

New mirrors25 cm x t10cm

Sapphire• We need a C-axis mirror(25cm x t15cm).• Reply from GT Crystal systems

– Current Max size of • C-axis mirror: 20cm x t15cm• A-Plane mirror:25cm x t15cm• “With time we feel can develop larger C-axis sapphire slabs to

achieve your goal of 25cm x 15cm sapphire mirrors with our HEM growth process.”

• Inquiring– when we can obtain C-axis mirror of 20cm x t15cm?– price and delivery time of max size of C-axis mirror(20cm x t15cm) and

A-Plane mirror (25cm x t15cm).– No answer (the quotations will be made in this week!).

appendix

Laser module （ Mitsubishi ）

Two rods and rotator Diffusive reflector +LD