Subscribe free to our newsletters via your
. 24/7 Space News .




Subscribe free to our newsletters via your




















PHYSICS NEWS
Increasing the sensitivity of next-generation gravitational wave detectors
by Staff Writers
Washington DC (SPX) Feb 14, 2017


The researchers created a modified pre-mode cleaner (left) that compensates for astigmatism that affects a Laguerre-Gauss mode laser. The astigmatism arises when the laser hits curved mirrors at an angle. Using concave mirrors at position 1 and 2 and planar mirrors at positions 3 and 4 compensates for this optical error such that a clean Laguerre Gauss mode is transmitted (right). Image courtesy Andreas Noack, Albert Einstein Institute.

Nearly one year ago the LIGO Collaboration announced the detection of gravitational waves, once again confirming Einstein's theory of General Relativity. This important discovery by the Advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO) has spurred great interest in improving these advanced optical detectors.

The mission of gravitational wave scientists worldwide is to make gravitational wave detection a routine occurrence. Scientists from the institute that developed the lasers used in Advanced LIGO have made significant progress to support that goal.

Advanced LIGO is a 2.5-mile long optical device known as an interferometer that uses laser light to detect gravitational waves coming from distant cosmic events such as colliding black holes or collapsing stars. Improving the stability of the laser source and decreasing noise that can hide weak signals coming from gravitational waves could help improve the sensitivity of gravitational wave detectors.

"We have made significant progress towards stable laser sources for third-generation gravitational wave detectors and prototypes of those," said Benno Willke of the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) and Leibniz Universitat Hannover, leader of the research team.

"More stable lasers enable interferometers to sense gravitational waves that are weaker and from sources further away and thus reveal important insights into astrophysical events involving black holes and neutron stars."

The new work has been reported in two new papers in The Optical Society (OSA) journal Optics Letters.

Developing a more stable laser
Achieving stable and consistent laser power, with minimal noise, is crucial to the operation of sensitive laser-based instruments like gravitational wave detectors. The Advanced LIGO system uses a multiphotodetector array made up of photodiodes, which convert light into electrical current, to detect any power fluctuations in the laser and then correct these noise-inducing fluctuations using a feedback loop. A separate, identical multiphotodetector array is used to ensure the noise was reduced to the desired level.

"Although photodiodes are typically used to sense laser power noise, they can only accept around 50 milliwatts of light power each, rather than the 200 milliwatts a gravitational wave detector needs for sensitive noise measurements," said Willke. Albert Einstein Institute researchers overcame this problem by splitting the light beam among four photodiodes so that together, the array of photodiodes can accept the optimal amount of light and provide more sensitive noise detection.

To test the performance of the new multiphotodetector arrays, the researchers placed arrays identical to the ones used in Advanced LIGO into the AEI 10 meter prototype interferometer, a testbed instrument used for evaluating potential gravitational wave detector upgrades.

With the multiphotodetector arrays in the 10-meter prototype interferometer, the researchers demonstrated a laser power stability that was a factor of five better than what has been achieved by other groups. The stability matched closely to what they previously achieved in a tabletop laboratory experiment.

"This work shows that it's possible to transfer the stability level from the well-isolated environment of an optical table to a complicated experimental setup like this 10 meter prototype," said Willke. "We show that these photodiode arrays work as expected, meaning it should also be possible to achieve this high stability with the identical multiphotodetector arrays used in Advanced LIGO."

Laser beam shaping to reduce noise
Willke's research group also demonstrated that with a few minor modifications, gravitational wave detectors could be made more sensitive by using a laser in what is called a Laguerre-Gauss mode.

Advanced LIGO uses lasers in the standard Gaussian mode, which produce a solid circular beam like a laser pointer. Laguerre-Gauss mode lasers produce a beam that looks like a bullseye. Researchers have proposed using Laguerre-Gauss mode lasers in design concepts for a third-generation gravitational wave detector, known as the Einstein Telescope, which is expected to be 10 times more sensitive than today's instruments.

"The design of next-generation gravitational wave detectors is not fixed," said Willke. "Therefore, we are testing different types of lasers and demonstrating whether such lasers are available options for new gravitational wave detectors."

The researchers found that Laguerre-Gauss lasers are not compatible with devices known as "pre-mode cleaners" that Advanced LIGO uses to improve the stability of the laser beam. Andreas Noack, first author of the paper, discovered that the mirrors used in the mode cleaners cause a refractive error called astigmatism.

Utilizing a geometric trick to compensate for this error, the researchers built a modified pre-mode cleaner and showed that it compensated for the astigmatism and transmitted the Laguerre-Gauss mode even at the high laser power level used by gravitational wave detectors.

"This new type of pre-mode cleaner will make designs such as the Einstein telescope possible," said Willke. "We can only build these types of third generation gravitational wave detectors if we can build a laser source that can be used with those designs. We demonstrate here an additional step in the feasibility study for a light source that could be used in future gravitational wave detectors."

Papers: J. Junker, P. Oppermann, B. Willke, "Shot-noise-limited laser power stabilization for the AEI 10m Prototype interferometer," Opt. Lett., Vol. 42, Issue 4, 755-758, (2017). DOI: 10.1364/OL.42.000755. and Andreas Noack, C. Bogan, B. Willke, "Higher-Order Laguerre-Gauss Modes in (Non-) Planar Four-Mirror Cavities for Future Gravitational Wave Detectors," Opt. Lett., Vol. 42, Issue 4, 751-754, (2017). DOI: 10.1364/OL.42.000751.


Comment on this article using your Disqus, Facebook, Google or Twitter login.

Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
Advanced Laser Interferometer Gravitational-Wave Observatory
The Physics of Time and Space






Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
PHYSICS NEWS
New laser technology from Hannover enables more sensitive gravitational-wave detectors
Munich, Germany (SPX) Feb 10, 2017
One year ago, the first direct detection of gravitational waves was announced. Laser experts from the Max Planck Institute for Gravitational Physics (Albert Einstein Institute; AEI), from the Leibniz Universitat Hannover, and from the Laser Zentrum Hannover e.V. (LZH) played leading roles in this discovery, because their super-precise laser technology at the heart of the LIGO instruments in the ... read more


PHYSICS NEWS
NASA to develop oxygen recovery technologies for future deep space missions

Art and space enter a new dimension

Russia's first private space tourism craft flight test set for 2020

Next SpaceX mission will deliver slew of experiment payloads to ISS

PHYSICS NEWS
Airbus Safran Launchers: 77th consecutive successful launch for Ariane 5

SpaceX poised to launch cargo from historic NASA pad

Airbus Safran Launchers: 77th consecutive successful launch for Ariane 5

India puts record 104 satellites into orbit

PHYSICS NEWS
Opportunity passes 44 kilometers of surface travel after 13 years

Scientists shortlist three landing sites for Mars 2020

Scientists say Mars valley was flooded with water not long ago

ISRO saves its Mars mission spacecraft from eclipse

PHYSICS NEWS
Chinese cargo spacecraft set for liftoff in April

China looks to Mars, Jupiter exploration

China's first cargo spacecraft to leave factory

China launches commercial rocket mission Kuaizhou-1A

PHYSICS NEWS
Iridium Announces Target Date for Second Launch of Iridium NEXT

Italy, Russia working closely on Mars exploration, Earth monitoring satellites

NASA seeks partnerships with US companies to advance commercial space technologies

A New Space Paradigm

PHYSICS NEWS
Most stretchable elastomer for 3-D printing

After 15 years, SABER on TIMED Still Breaks Ground from Space

ANU scientists make new high-tech liquid materials

Curtiss-Wright offers COTS Module for measuring microgravity acceleration

PHYSICS NEWS
Exoplanetary moons formed by giant impacts could be detected by Kepler

The heart of a far-off star beats for its planet

Astronomy team finds more than 100 exoplanet candidates

Possibility of Silicon-Based Life Grows

PHYSICS NEWS
NASA receives science report on Europa lander concept

New Horizons Refines Course for Next Flyby

It's Never 'Groundhog Day' at Jupiter

Public to Choose Jupiter Picture Sites for NASA Juno




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News








The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement