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International Summer Research Program in Gravitational-Wave Physics:
Research Experiences for Undergraduates around the world

• Stabilization of high power fiber amplifier:
  The AEI and the Laser Zentrum Hannover built and installed the the Advanced LIGO 200W Laser system and its stabilization. For the next generation of gravitational wave detectors, fiber based high power laser systems are a promising technology. The LZH has developed a 200W fiber amplifier system which is currently being operated at AEI in a long term test. In parallel, work is underway to reduce the power, frequency and pointing fluctuations of this laser to a level achieved for the Advanced LIGO system and if possible beyond. The IREU student will be involved in the characterization and testing of this high power fiber amplifier. She or he will learn about the design of the laser systems, will work with optical analyzer cavities, measure and optimize the various feedback systems, and help with the analysis of the long term measurements.
  Mentor: Benno Willke
  Related Project 2009: "Installation and Characterization of the AdvLIGO 200W PSL"
  Related Project 2013: "High Power Fibre Laser Development"
  
• Ranging and data transfer for LISA:
  LISA is a future space-based gravitational wave detector designed to measure gravitational waves in the mHz frequency range. The three LISA spacecraft forming the LISA constellation are separated by 5 million km. They have to measure and monitor their absolute distance with 30m accuracy to cancel the laser frequency noise. The spacecraft also have to exchange data between each other to keep the configuration aligned and collect the science data at one spacecraft before transmitting them to the ground. For this purpose ranging and data signals will be modulated and extracted from the main laser beam. The student will be involved in an experiment to validate the ranging and data transfer concept.
  Mentor: Gerhard Heinzel
  Related Project 2009: "Ranging Implementation: Signal Processing Development"
• Offset phase locking with fast digital phasemeter:
  The LISA lasers will all be phase locked to one master laser. These phase lock loops will use fast digital phasemeters which are compatible with the phase meter used for the science signals. The student will be involved in the design, optimization, and test of these phase lock loops.
  Mentor: Gerhard Heinzel
  Related Project 2012: "Building and Testing a Phase Modulated Homodyne Mach-Zender Interferometer"
  
• Testing the full clock noise transfer chain:
  LISA requires to measure the relative noise between the ultra-stable oscillators (USO) which provide the clock signals on each spacecraft. These measurements require to modulate the laser beam with a sidetone derived form the USO, to compare it with another sidetone generated by the USO on the other spacecraft. The performance of this relative noise measurement depends on the phase fidelity of the generation of the modulation tine, the modulators, as well as the receivers. The student will be involved in the design, testing, and simulation of the entire chain.
  Mentor: Gerhard Heinzel
  
• Triple-pendulum mirror suspensions for the AEI 10m prototype interferometer:
  Many optical components in the AEI 10m prototype interferometer need to be suspended by means of multiple pendula to provide the required seismic isolation. These suspension systems are mounted on actively-controlled, seimically-isolated benches inside a large ultra-high vacuum system. Each suspension needs to be electronically controlled in all six degrees of freedom. The suspension systems in use differ substantially according to their individual purpose. Steel wire triple pendula with two additional vertical stages support 5.6kg mirrors for the mode-cleaning/frequency-reference cavity. For the interferometer core optics, however, multiple cascaded pendula with an all-silica monolithic final stage carry 100g mirrors. One project would concern fabrication and installation of these suspension systems.
  Mentor: Stefan Goßler
  Related Project 2013: "Reference Cavity Suspension Commissioning Of the 10 m Prototype"
  
• Enhanced digital real-time control and data acquisition system for the AEI 10m prototype interferometer:
  All experiments that will be operated in the AEI 10m prototype interferometer envelope will be digitally controlled by a real-time computer system that runs the software package EPICS. Digital servo loops and filters will be implemented via SimuLink models. This digital control and data acquisition system (CDS) is currently being set up and tested. Among the controlled systems is the active seismic isolation of the 750kg suspended optical benches from 10mHz to 30Hz, the automatic beam alignment, and the global control of the 10m Michelson interferometer with Fabry Perot cavities in it's arms. Further development and adaption of the CDS system are ongoing tasks in this area.
  Mentor: Stefan Goßler
  Related Project 2008: "Designing Optical Layouts for the AEI 10 meter Prototype"
  Related Project 2010: "Reflectance of Coated Mirrors in the 10m Prototype Interferometer"
• Characterization of GEO600: This project is no longer available.
  The tasks performed in characterizing interferometric gravitational wave detectors for commissioning and for the analysis of data have a large overlap. Currently, GEO600 is undergoing an upgrade to surpass all current instruments in the regime above 1kHz. For a time, the new GEO-HF will be the only running interferometric gravitational wave detector in the world. Studies of the transients in the detector are especially important for the types of gravitational wave searches that are possible with a single, high frequency detector. Depending on a student's background and interests, possible projects could include investigating lock losses, developing new system monitors, engaging in noise hunting, or extending work on the state space model of the control systems started by a previous student.
  Mentor: Jonathan Leong
  Related Project 2010: "Building a State Space Model of the GEO600 Control Architechture"
  Related Project 2011: "Improvements to Data Characterization with Hierarchical Algorithm for Curves and Ridges (HACR)"
  
• AEI Project 2007: "Improving and characterizing the burst-hardware injection pipeline for GEO600"
  AEI Project 2008: "Back-Reflected Light and the Reduction of Nonreciprocal Phase Noise in the Fiber Back-Link on LISA"
  AEI Project 2009: "Progress Towards A Squeezed Light Enhanced Zero-Area Sagnac Interferometer"