Building blocks for future detectors: Silicon test masses and 1550 nm laser light

Schnabel, R.; Britzger, M.; Brückner, Frank; Burmeister, O.; Danzmann, K.; Duck, J.P.; Eberle, T.; Friedrich, Daniel; Lück, H.; Mehmet, M.; Nawrodt, R.; Steinlechner, S.; Willke, B.

doi:10.1088/1742-6596/228/1/012029

Cited by 22 publications

(21 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Results of multiple measurements of Q-factors of fused silica mechanical resonators obtained in different labs were [17,18]). collected for generating the empirical model of the room temperature loss in fused silica.…”

Section: Results Of Experimental Investigation Of Acoustic Losses In mentioning

confidence: 99%

Technology for the next gravitational wave detectors

Mitrofanov

Chao

Pan

et al. 2015

Sci. China Phys. Mech. Astron.

View full text Add to dashboard Cite

This paper reviews some of the key enabling technologies for advanced and future laser interferometer gravitational wave detectors, which must combine test masses with the lowest possible optical and acoustic losses, with high stability lasers and various techniques for suppressing noise. Sect. 1 of this paper presents a review of the acoustic properties of test masses. Sect. 2 reviews the technology of the amorphous dielectric coatings which are currently universally used for the mirrors in advanced laser interferometers, but for which lower acoustic loss would be very advantageous. In sect. 3 a new generation of crystalline optical coatings that offer a substantial reduction in thermal noise is reviewed. The optical properties of test masses are reviewed in sect. 4, with special focus on the properties of silicon, an important candidate material for future detectors. Sect. 5 of this paper presents the very low noise, high stability laser technology that underpins all advanced and next generation laser interferometers

show abstract

Section: Results Of Experimental Investigation Of Acoustic Losses In mentioning

confidence: 99%

Technology for the next gravitational wave detectors

Mitrofanov

Chao

Pan

et al. 2015

Sci. China Phys. Mech. Astron.

View full text Add to dashboard Cite

show abstract

“…An all-silicon interferometer can be made insensitive to temperature fluctuations as the coefficient of thermal expansion of silicon has a zero crossing near 124 K. In this temperature range the Q of silicon is orders of magnitude higher than in the conventional cavity glass materials such as Ultralow Expansion glass (ULE) or fused silica [23]. A similar approach has been used with relatively low-finesse optical Fabry-Perot interferometers [24] and has recently been proposed for gravitational wave detection [25]. A remaining issue to be solved in the future is the thermal noise associated with optical coating, but its contribution can be reduced with the use of a longer cavity spacer.…”

Section: Introductionmentioning

confidence: 99%

A sub-40-mHz-linewidth laser based on a silicon single-crystal optical cavity

et al. 2012

View full text Add to dashboard Cite

State-of-the-art optical oscillators based on lasers frequency stabilized to high finesse optical cavities are limited by thermal noise that causes fluctuations of the cavity length. Thermal noise represents a fundamental limit to the stability of an optical interferometer and plays a key role in modern optical metrology. We demonstrate a novel design to reduce the thermal noise limit for optical cavities by an order of magnitude and present an experimental realization of this new cavity system, demonstrating the most stable oscillator of any kind to date. The cavity spacer and the mirror substrates are both constructed from single crystal silicon and operated at 124 K where the silicon thermal expansion coefficient is zero and the silicon mechanical loss is small. The cavity is supported in a vibration-insensitive configuration, which, together with the superior stiffness of silicon crystal, reduces the vibration related noise. With rigorous analysis of heterodyne beat signals among three independent stable lasers, the silicon system demonstrates a fractional frequency stability of 1 × 10 −16 at short time scales and supports a laser linewidth of <40 mHz at 1.5 µm, representing an optical quality factor of 4 × 10 15 .

show abstract

“…Because of its high mechanical Q-factor at cryogenic temperatures [8,9], crystalline silicon (c-Si) is considered as a test-mass material [7] for future GWDs. c-Si shows a high optical absorption at 1064 nm.…”

Section: Introductionmentioning

confidence: 99%

Optical absorption measurement at 1550 nm on a highly-reflective Si/SiO ₂ coating stack

Steinlechner

Khalaidovski

Schnabel

2014

Class. Quantum Grav.

View full text Add to dashboard Cite

Future laser-interferometric gravitational wave detectors (GWDs) will potentially employ test mass mirrors from crystalline silicon and a laser wavelength of 1550 nm, which corresponds to a photon energy below the silicon bandgap. Silicon might also be an attractive high-refractive index material for the dielectric mirror coatings. Films of amorphous silicon (a-Si), however, have been found to be significantly more absorptive at 1550 nm than crystalline silicon (c-Si). Here, we investigate the optical absorption of a Si/SiO 2 dielectric coating produced with the ion plating technique. The ion plating technique is distinct from the standard state-of-the-art ion beam sputtering technique since it uses a higher processing temperature of about 250• C, higher particle energies, and generally results in higher refractive indices of the deposited films. Our coating stack was fabricated for a reflectivity of R = 99.95% for s-polarized light at 1550 nm and for an angle of incidence of 44• . We used the photothermal self-phase modulation technique to measure the coating absorption in s-polarization and p-polarization. We obtained α coat s = (1035 ± 42) ppm and α coat p = (1428 ± 97) ppm. These results correspond to an absorption coefficient which is lower than literature values for a-Si which vary from 100 cm −1 up to 2000 cm −1 . It is, however, still orders of magnitude higher than expected for c-Si and thus still too high for GWD applications.

show abstract

Building blocks for future detectors: Silicon test masses and 1550 nm laser light

Cited by 22 publications

References 46 publications

Technology for the next gravitational wave detectors

Technology for the next gravitational wave detectors

A sub-40-mHz-linewidth laser based on a silicon single-crystal optical cavity

Optical absorption measurement at 1550 nm on a highly-reflective Si/SiO ₂ coating stack

Contact Info

Product

Resources

About

Building blocks for future detectors: Silicon test masses and 1550 nm laser light

Cited by 22 publications

References 46 publications

Technology for the next gravitational wave detectors

Technology for the next gravitational wave detectors

A sub-40-mHz-linewidth laser based on a silicon single-crystal optical cavity

Optical absorption measurement at 1550 nm on a highly-reflective Si/SiO 2 coating stack

Contact Info

Product

Resources

About

Optical absorption measurement at 1550 nm on a highly-reflective Si/SiO ₂ coating stack