An infrared integrated optic astronomical beam combiner for stellar interferometry at 3-4 μm

Hsiao, Hsien Kai; Winick, Kim A.; Berger, J. P.

doi:10.1364/oe.17.018489

Cited by 39 publications

(19 citation statements)

References 28 publications

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“…One of the most popular materials for active integrated optics is Lithium Niobate, where high contrast (36dB) rejection ratios have been obtained in the mid-IR 62 . The transparency range of this material allows to cover from mid-infrared (L-band) 70 down to visible 71 . One of the main issues concerning interferometry applications in astronomy is the chromatic dispersion of the fringes and the high propagation losses in the mid-IR due to low field confinement.…”

Section: Active Integrated Opticsmentioning

confidence: 99%

Astronomical photonics in the context of infrared interferometry and high-resolution spectroscopy

et al. 2016

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We review the potential of Astrophotonics, a relatively young field at the interface between photonics and astronomical instrumentation, for spectro-interferometry. We review some fundamental aspects of photonic science that drove the emergence of astrophotonics, and highlight the achievements in observational astrophysics. We analyze the prospects for further technological development also considering the potential synergies with other fields of physics (e.g. non-linear optics in condensed matter physics). We also stress the central role of fiber optics in routing and transporting light, delivering complex filters, or interfacing instruments and telescopes, more specifically in the context of a growing usage of adaptive optics.

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Section: Active Integrated Opticsmentioning

confidence: 99%

Astronomical photonics in the context of infrared interferometry and high-resolution spectroscopy

et al. 2016

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“…The three main technological platforms that have been explored for midinfrared IO technologies are based on ion exchange/diffusion, chemical etching/lithography, and ultrafast laser writing. Ion diffusion in lithium niobate glass has demonstrated the feasibility of active IO beam combiners in the 3.2−3.8 µm range (Hsiao et al 2009;Heidmann et al 2012). However, broadband operation by Martin et al (2014) has evidenced large chromatic dispersion and low-confinement of the modes, which resulted in propagation losses as high as 16 dB/cm.…”

Section: Introductionmentioning

confidence: 99%

Integrated optics prototype beam combiner for long baseline interferometry in the L and M bands

Tepper

Labadie

Diener

et al. 2017

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Context. Optical long baseline interferometry is a unique way to study astronomical objects at milli-arcsecond resolutions not attainable with current single-dish telescopes. Yet, the significance of its scientfic return strongly depends on a dense coverage of the uv-plane and a highly stable transfer function of the interferometric instrument. In the last few years, integrated optics (IO) beam combiners have facilitated the emergence of 4-telescope interferometers such as PIONIER or GRAVITY, boosting the imaging capabilities of the VLTI. However, the spectral range beyond 2.2 µm is not ideally covered by the conventional silica based IO. Here, we consider new laser-written IO prototypes made of gallium lanthanum sulfide (GLS) glass, a material that permits access to the mid-infrared spectral regime. Aims. Our goal is to conduct a full characterization of our mid-IR IO two-telescope coupler in order to measure the performance levels directly relevant for long-baseline interferometry. We focus in particular on the exploitation of the L and M astronomical bands. Methods. We use a dedicated Michelson-interferometer setup to perform Fourier transform spectroscopy on the coupler and measure its broadband interferometric performance. We also analyze the polarization properties of the coupler, the differential dispersion and phase degradation, as well as the modal behavior and the total throughput. Results. We measure broadband interferometric contrasts of 94.9% and 92.1% for unpolarized light in the L and M bands. Spectrally integrated splitting ratios are close to 50%, but show chromatic dependence over the considered bandwidths. Additionally, the phase variation due to the combiner is measured and does not exceed 0.04 rad and 0.07 rad across the L and M band, respectively. The total throughput of the coupler including Fresnel and injection losses from free-space is 25.4%. Furthermore, differential birefringence is low (<0.2 rad), in line with the high contrasts reported for unpolarized light. Conclusions. The laser-written IO GLS prototype combiners prove to be a reliable technological solution with promising performance for mid-infrared long-baseline interferometry. In the next steps, we will consider more advanced optical functions, as well as a fiberfed input, and we will revise the optical design parameters in order to further enhance the total throughput and achromatic behavior.

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“…A multielement photonic circuit such as an on-chip beam combiner [8] may be composed of numerous passive and active elements, such as tunable phase shifters, optical modulators, passive routers and spectrum filters, and possibly wavelength conversion elements for accessing more efficient detectors. The materials available on the platform determine the means available to achieve these effects.…”

Section: Introductionmentioning

confidence: 99%

Mid-infrared integrated waveguide modulators based on silicon-on-lithium-niobate photonics

Chiles

Fathpour

2014

Optica

120

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Heterogeneous integration techniques, such as direct bonding, have enabled solutions to many problems facing integrated photonics. In particular, the relatively new field of mid-infrared (mid-IR) integrated photonics has been hindered by the availability of functional, transparent substrates in this wavelength range.The key to achieving compact, high-performance optical modulation and frequency conversion is the monolithic integration of silicon photonics with a material with high second-order nonlinear susceptibility. By transferring large areas of thin, monocrystalline silicon to bulk lithium niobate (LiNbO 3 ) substrates, the first silicon-based platform to exploit the Pockels or linear electro-optic effect in the mid-IR range is achieved. Integrated Mach-Zehnder interferometer modulators with an extinction ratio of ∼8 dB, a half-wave voltage-length product of 26 V · cm, and an on-chip insertion loss of 3.3 dB are demonstrated at a wavelength of 3.39 μm. Ultrathin optical waveguides fabricated and characterized on this platform exhibit a low transverse electric mode linear propagation loss of 2.5 dB∕cm. Future capabilities such as wideband difference frequency generation for integrated mid-IR sources are envisioned for the demonstrated silicon-on-lithium-niobate platform.

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An infrared integrated optic astronomical beam combiner for stellar interferometry at 3-4 μm

Cited by 39 publications

References 28 publications

Astronomical photonics in the context of infrared interferometry and high-resolution spectroscopy

Astronomical photonics in the context of infrared interferometry and high-resolution spectroscopy

Integrated optics prototype beam combiner for long baseline interferometry in the L and M bands

Mid-infrared integrated waveguide modulators based on silicon-on-lithium-niobate photonics

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