Design and fabrication of stress-compensated optical coatings: Fabry–Perot filters for astronomical applications

Denus-Baillargeon, Marie-Maude de; Schmitt, Thomas; Larouche, Stéphane; Martinů, L.

doi:10.1364/ao.53.002616

Cited by 24 publications

(14 citation statements)

References 37 publications

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“…Secondly, layer materials with opposite stress can be employed to decrease the multilayer stress, although the available materials are very limited [7,11]. Thirdly, backside coatings and thermal annealing treatment have been commonly used to control stress-induced deformation, the corresponding operation and disadvantage of the approaches are reviewed in other literature [4,11,13,[17][18][19][20]. Besides, thermal oxide patterning and ion implantation have been successfully used to compensate film stress in thin silicon substrates for X-ray optical applications [21,22].…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Ultralow Stress TiO2/SiO2 Optical Coatings by Plasma Ion-Assisted Deposition

Guo

Kong

2020

Coatings

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Optical and mechanical properties of multilayer coatings depend on the selected layer materials and the deposition technology; therefore, knowledge of the performances of thin films is essential. In the present work, titanium dioxide (TiO2) and silicon dioxide (SiO2) thin films have been prepared by plasma ion-assisted deposition (PIAD). The optical, structural, and mechanical properties of thin films have been investigated using spectrometer/ellipsometer, X-ray diffraction (XRD), atomic force microscopy (AFM), and laser interferometer. The results show that TiO2 film fabricated by PIAD induces a high refractive index, wide optical band gap, amorphous structure, smooth surface, and tensile stress. In the case of SiO2 film, high bias voltage leads to dense structure and compressive stress. As an application, a three-wavelength high reflectance at 632.8, 808, and 1550 nm was optimized and deposited. The dependence of total stress in the multilayer on the substrate temperature was studied as well. In conclusion, it was demonstrated that PIAD is an effective method for the preparation of ultralow stress TiO2/SiO2 multilayer films. The achieved stress was as low as 1.4 MPa. The result could provide guidance to the stress optimization of most optical components without prefiguring, backside coating, and postdeposition treatments.

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Section: Introductionmentioning

confidence: 99%

Fabrication of Ultralow Stress TiO2/SiO2 Optical Coatings by Plasma Ion-Assisted Deposition

Guo

Kong

2020

Coatings

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“…Let us analyze the last two approaches. The first has already been implemented by several other research teams [14,15]. In their work, back surface coating was implemented in order to both perform stress-compensation but also to generate a specific optical function such as an antireflection or broadband rejection.…”

Section: Stress Compensation For Ir-based Mirrorsmentioning

confidence: 99%

Coating stress analysis and compensation for iridium-based x-ray mirrors

et al. 2018

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Iridium-based coatings for mirrors of X-ray telescopes are studied. In particular, stress induced deformation is characterized and shown to be compressive and equal to -1786 MPa. Two methods for stress compensation are then studied. One relies on the deposition of silica on the back surface of the substrate and a second one relies on the deposition of a chromium sublayer. Advantages and drawbacks of each of these techniques are presented.

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“…The former is minimized by avoiding any color-dependent optical elements. For the latter, mechanical stress (specific to coating process), aging, and lightinduced damage (mostly from high power lasers) are known to alter the reflectance of the mirror over time (Ennos 1966;de Denus-Baillargeon et al 2014). With an FP housed in a thermally controlled evacuated chamber, we believe dispersion vari-A&A proofs: manuscript no.…”

Section: The Fpi Transmission Spectrummentioning

confidence: 99%

A laser-lock concept to reach cm s^-1-precision in Doppler experiments with Fabry-Pérot wavelength calibrators

Reiners¹,

Banyal²,

Ulbrich

2014

A&A

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State-of-the-art Doppler experiments require wavelength calibration with precision at the cm s −1 level. A low-finesse Fabry-Pérot interferometer (FPI) can provide a wavelength comb with a very large bandwidth as required for astronomical experiments, but unavoidable spectral drifts are difficult to control. Instead of actively controlling the FPI cavity, we propose to passively stabilize the interferometer and track the time-dependent cavity length drift externally using the 87 Rb D 2 atomic line. A dual-finesse cavity allows drift tracking during observation. In the low-finesse spectral range, the cavity provides a comb transmission spectrum tailored to the astronomical spectrograph. The drift of the cavity length is monitored in the high-finesse range relative to an external standard: a single narrow transmission peak is locked to an external cavity diode laser and compared to an atomic frequency from a Doppler-free transition. Following standard locking schemes, tracking at sub-mm s −1 precision can be achieved. This is several orders of magnitude better than currently planned high-precision Doppler experiments, and it allows freedom for relaxed designs including the use of a single-finesse interferometer under certain conditions. All components for the proposed setup are readily available, rendering this approach particularly interesting for upcoming Doppler experiments. We also show that the large number of interference modes used in an astronomical FPI allows us to unambiguously identify the interference mode of each FPI transmission peak defining its absolute wavelength solution. The accuracy reached in each resonance with the laser concept is then defined by the cavity length that is determined from the one locked peak and by the group velocity dispersion. The latter can vary by several 100 m s −1 over the relevant frequency range and severely limits the accuracy of individual peak locations, although their interference modes are known. A potential way to determine the absolute peak positions is to externally measure the frequency of each individual peak with a laser frequency comb (LFC). Thus, the concept of laser-locked FPIs may be useful for applying the absolute accuracy of an LFC to astronomical spectrographs without the need for an LFC at the observatory.

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Design and fabrication of stress-compensated optical coatings: Fabry–Perot filters for astronomical applications

Cited by 24 publications

References 37 publications

Fabrication of Ultralow Stress TiO2/SiO2 Optical Coatings by Plasma Ion-Assisted Deposition

Fabrication of Ultralow Stress TiO2/SiO2 Optical Coatings by Plasma Ion-Assisted Deposition

Coating stress analysis and compensation for iridium-based x-ray mirrors

A laser-lock concept to reach cm s^-1-precision in Doppler experiments with Fabry-Pérot wavelength calibrators

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Design and fabrication of stress-compensated optical coatings: Fabry–Perot filters for astronomical applications

Cited by 24 publications

References 37 publications

Fabrication of Ultralow Stress TiO2/SiO2 Optical Coatings by Plasma Ion-Assisted Deposition

Fabrication of Ultralow Stress TiO2/SiO2 Optical Coatings by Plasma Ion-Assisted Deposition

Coating stress analysis and compensation for iridium-based x-ray mirrors

A laser-lock concept to reach cm s-1-precision in Doppler experiments with Fabry-Pérot wavelength calibrators

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Product

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A laser-lock concept to reach cm s^-1-precision in Doppler experiments with Fabry-Pérot wavelength calibrators