Precise Measurementsof Time and Space
Artist’s rendering of an optical cavity with crystalline coatings Image courtesy of Brad Baxley, JILA Scientific Reports Office
Single-Crystal Coatings are the Key
Crystalline Mirror Solutions manufactures low-noise reflective optics using a proprietary coating technology.
High-performance optical coatings are critical for a variety of scientific endeavors and commercial industries, including broadband communication, navigation, and sensing. Our crystalline coatings represent an entirely new paradigm in optical coating technology impacting cavity end mirrors for state-of-the-art ultrastable lasers, cavity-ringdown systems, and ring-laser gyroscopes. Moreover, exploiting the high thermal conductivity and active electro-optic properties of the materials we employ, crystalline coatings promise to have a tremendous impact in ultra-fast and high-power laser systems.
Reduction of Brownian noise
Crystalline coatings enable a 10-100x reduction in mechanical dissipation.
CMS has developed a new “Crystalline Supermirror” technology, which addresses the technical limitations of excess thermal noise in sputtered coatings. Due to the unique properties of our semiconductor coating material, our Crystalline Supermirrors provide a 10×-100× reduction in mechanical dissipation, and thus corresponding reductions in Brownian noise, when compared with typical ion-beam sputtered films. Furthermore, this unique mirror technology exhibits additional advantages such as very low optical losses in the mid-infrared and high thermal conductivity, more than 50x greater than competing dielectric mirror technologies.
Substrate-transfer and bonding process
Building upon earlier work in high-performance AlGaAs-based optomechanical resonators, CMS has developed a groundbreaking coating technology that enables the transfer of monocrystalline multilayers onto essentially arbitrary (including curved) substrates. Exploiting this technique, we are able to bond single-crystal GaAs/AlGaAs semiconductor multilayers on a large variety of substrate materials including fused silica, sapphire, Si, SiC, diamond, and YAG.
– Low thermal noise
– High IR reflectivity
– High thermal conductivity
While AlGaAs-based distributed Bragg reflectors (DBRs) have been applied for the fabrication of optical interference coatings since the late 1970s, until the development of our substrate-transfer technology, these materials had not been employed as general optical coatings. With the ability to transfer AlGaAs onto arbitrary substrates, we can now generate ultrastable mirrors with low Brownian noise, high reflectivity MIR mirrors, and high-thermal conductivity active mirror systems.
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B. J. Bjork, T. Q. Bui, O. H. Heckl, P. B. Changala, B. Spaun, P. Heu, D. Follman, C. Deutsch, G. D. Cole, M. Aspelmeyer, M. Okumura, J. Ye, “Direct frequency comb measurement of OD + CO → DOCO kinetics”, Science, Vol. 354, Issue 6311, 444-448, 28 Oct 2016.
G. D. Cole, W. Zhang, B. J. Bjork, D. Follman, P. Heu, C. Deutsch, L. Sonderhouse, J. Robinson, C. Franz, A. Alexandrovski, M. Notcutt, O. H. Heckl, J. Ye, M. Aspelmeyer, “High-performance near- and mid-infrared crystalline coatings”, Optica, Vol. 3, No. 6, 647-656, June 2016.
“… achieved optical absorption values below 1 ppm in the NIR…”
“… experimentally verified a maximum cavity finesse of 3×10^5 near 1550 nm…”
A. Diebold, T. Zengerle, C. G. E. Alfieri, C. Schriber, F. Emaury, M. Mangold, M. Hoffmann, C. J. Saraceno, M. Golling, D. Follman, G. D. Cole, M. Aspelmeyer, T. Südmeyer, and U. Keller, “Optimized SESAMs for kilowatt-level ultrafast lasers,” Opt. Express 24, issue 10, 10512-10526, May 2016.
“Our best SESAMs are fabricated using a novel substrate-transfer direct bonding technique…”
“…show excellent surface flatness […], order-of-magnitude improved heat removal, and negligible deformation with absorbed power […] without altering the saturation behavior…”
T. Chalermsongsak, E. D. Hall, G. D. Cole, D. Follman, F. Seifert, K. Arai, E. K. Gustafson, J. R. Smith, M. Aspelmeyer, R. X. Adhikari, “Coherent cancellation of photothermal noise in GaAs/Al0.92Ga0.08As Bragg mirrors,” Metrologia, vol. 53, no. 2, 860, 9 March 2016.
“… demonstrated cancellation of photothermal noise in high-reflectivity substrate-transferred AlGaAs coatings… ”
“… cancellation was achieved by optimizing the coating layer structure […] hence minimizing the total coating thermo-optic noise…”
Mitrofanov Valery P., Chao Shiuh, Pan Huang-Wei, Kuo Ling-Chi, Cole Garrett, Degallaix Jerome & Willke Benno, “Technology for the next gravitational wave detectors”, Science China, Physics, Mechanics & Astronomy, vol. 58, no. 12: 120404, December 2015.
“…a new generation of crystalline optical coatings that offer a substantial reduction in thermal noise is reviewed…”
“…we have successfully demonstrated high-yield bonding of GaAs to fused silica at a diameter of 10 cm, with the process being immediately transferable to sizes up to 20 cm.”
J. Steinlechner, I. W. Martin, A. Bell, G. D. Cole, J. Hough, S. Penn, S. Rowan, S. Steinlechner, “Mapping the optical absorption of a substrate-transferred crystalline AlGaAs coating at 1.5 µm,” Classical and Quantum Gravity, vol. 32, no. 10, 105008, 21 May 2015.
“… an upper limit for the coating absorption [… ] of αHR ⩽ (3.6 ± 1.3) ppm […] at 1530 nm”
K. U. Schreiber, R. J. Thirkettle, R. B. Hurst, D. Follman, G. D. Cole, M. Aspelmeyer, J.-P. R. Wells, “Sensing Earth rotation with a helium-neon ring laser operating at 1.15 µm,” Optics Letters, vol. 40, no. 8, pp. 1705-1708, 15 April 2015.
“… first implementation of crystalline coatings in an active laser cavity…”
“… expands the core application area of these […] mirrors to inertial sensing systems…”
G. D. Cole, W. Zhang, M. J. Martin, J. Ye, M. Aspelmeyer, “Tenfold reduction of Brownian noise in high-reflectivity optical coatings,” Nature Photonics, vol. 7, no. 8, pp. 644-650, August 2013.
“… tenfold reduction in coating loss angle compared with state-of-the-art IBS-deposited multilayers … “
“… measurement […] yielded a cavity finesse of 150,000…”
G. D. Cole, “Cavity optomechanics with low-noise crystalline mirrors,” SPIE Optics & Photonics, Optical Trapping and Optical Micromanipulation IX, San Diego, CA, USA, 8458-07, 12–16 August 2012.
“…epitaxial AlGaAs multilayers exhibit extremely promising characteristics for […] ultra-low-Brownian-noise macroscopic mirror systems for precision measurement applications…”
“…devices demonstrate typical cryogenic [mechanical] Q values in excess of 10^5 […] with a maximum measured Q of 2.2×10^5 at 10 K …”
“…If a successful transfer process can be developed […] low-loss epitaxial AlGaAs Bragg mirrors would be an exciting alternative to current dielectric reflectors.”
G. D. Cole, I. Wilson-Rae, K. Werbach, M. R. Vanner, M. Aspelmeyer, “Phonon tunneling dissipation in mechanical resonators,” Nature Communications, vol. 2, article 231, 8 March 2011.
“…we develop and test an efficient method for calculating the clamping loss of high-Q mechanical resonators.”
G. D. Cole, Y. Bai, M. Aspelmeyer, E. A. Fitzgerald, “Free-standing AlxGa1-xAs heterostructures by gas-phase etching of germanium,” Applied Physics Letters, vol. 96, no. 26, 261102, 28 June 2010.
“We outline a facile fabrication technique for the realization of free-standing AlxGa1−xAs heterostructures of arbitrary aluminum content.”
“…we build upon recent advances in the growth of III–V/Ge heterostructures16 and demonstrate the feasibility of fabricating free-standing monocrystalline films…”
G. D. Cole, I. Wilson-Rae, M. R. Vanner, S. Gröblacher, J. Pohl, M. Zorn. M. Weyers, A. Peters, M. Aspelmeyer, “Megahertz monocrystalline optomechnaical resonators with minimal dissipation,” 23rd IEEE International Conference on MEMS, Hong Kong, China, TP133, 847-850, 24–28 January 2010.
“…We demonstrate high-performance monocrystalline optomechanical resonators employing a novel free-free support geometry.”
“These devices exhibit eigenfrequencies approaching 4 MHz, reflectivities exceeding 99.98% at 1064 nm, and mechanical quality factors (Q) of 0.8×10^5…”
G. D. Cole, S. Gröblacher, K. Gugler, S. Gigan, M. Aspelmeyer, “Monocrystalline AlxGa1-xAs heterostructures for high-reflectivity high-Q micromechanical resonators in the megahertz regime,” Applied Physics Letters, vol. 92, no. 26, 261108, 30 June 2008.
“…the use of compound semiconductor materials such as GaAs […] allows for the generation of arbitrary stacks of high index-contrast materials that maintain nearly perfect crystalline order, resulting in significant improvements in the achievable mechanical quality factor…”
“We observe optical reflectivities exceeding 99.98% combined with mechanical quality factors up to 20 000 at 4 K for mechanical modes as high as 2 MHz.”