Advanced LIGO subsystems
are the organizational units of the overall project. Follow the links below to view the mission and progress of each subsystem.
Auxiliary Optics Core Optics
 
Data Acquisition Data and
Computing
Systems
 
Facilities
Modifications		 Input Optics
 
Interferometer
Control		 Pre-Stabilized
Laser
 
Seismic
Isolation		 Suspensions

Subsystem: Pre-Stabilized Laser

The pre-stabilized laser (PSL) provides frequency and intensity stabilized light for the Advanced LIGO interferometers at the specifications required for entrance to the Input Optics (IO) chain. The heart of the PSL is a three-stage laser system.

  • Stage one consists of a 2W non-planar ring-oscillator (NPRO) that uses a Nd:YAG crystal as the laser medium and resonator. The NPRO is pumped by laser diodes at 808 nm and produces a 1064nm beam. The PSL is able to meet LIGO's frequency stability requirement for the laser light in part through the performance of the NPRO's monolithic resonator.
  • The second stage delivers an output power of 35 W. Here the NPRO beam passes through four Nd:YVO4 crystals, also pumped at 808 nm.
  • The third stage, the high-power oscillator, contains an injection-locked ring oscillator that delivers roughly 220 W. Four Nd:YAG crystals are pumped at 808 nm, with the pump light traveling to the PSL table through optical fibers from a room dozens of meters away. A feedback loop locks stage three to stage two. Light produced in the latter two stages retains the extraordinary stability imparted by the NPRO at stage one.

The PSL contains a number of other components for control and further stabilization of the light, including a pre-mode cleaner, an electro-optic modulator that places sidebands on the main beam, and a resonant optical cavity that serves as a frequency reference.

 
      Photos courtesy AEI-Max Planck/LZH

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      PSL Frequency servo circuit board

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    PSL intensity servo photodiode array

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  PSL intensity servo photodiodes

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      Reference cavity output

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    Electrooptic modulator (top view)

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  PSL intensity servo photodiode array

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      Laser system diagnostic breadboard

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    Temporary home for Faraday isolator

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  PSL reference cavity

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      ALS equipment on PSL table

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    Readouts of PSL servos

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  High power oscillator output port

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      Pump light entering the homogenizer

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    PSL assembly

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  PSL arrives at LHO

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      35 W Enhanced LIGO laser

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    200 W aLIGO laser at AEI

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  200 W aLIGO laser at AEI

Additional PSL Photos

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