Building hybridized 28-baseline pupil-remapping photonic interferometers for future high-resolution imaging.

One key advantage of single-mode photonic technologies for interferometric use is their ability to easily scale to an ever-increasing number of inputs without a major increase in the overall device size, compared to traditional bulk optics. This is particularly important for the upcoming extremely large telescope (ELT) generation of telescopes currently under construction. We demonstrate the fabrication and characterization of a hybridized photonic interferometer, with eight simultaneous inputs, forming 28 baselines, which is the largest amount to date, to the best of our knowledge.

Scalable photonic-based nulling interferometry with the dispersed multi-baseline GLINT instrument.

Characterisation of exoplanets is key to understanding their formation, composition and potential for life. Nulling interferometry, combined with extreme adaptive optics, is among the most promising techniques to advance this goal. We present an integrated-optic nuller whose design is directly scalable to future science-ready interferometric nullers: the Guided-Light Interferometric Nulling Technology, deployed at the Subaru Telescope.

High-performance 3D waveguide architecture for astronomical pupil-remapping interferometry.

The detection and characterization of extra-solar planets is a major theme driving modern astronomy. Direct imaging of exoplanets allows access to a parameter space complementary to other detection methods, and potentially the characterization of exoplanetary atmospheres and surfaces. However achieving the required levels of performance with direct imaging from ground-based telescopes (subject to Earth's turbulent atmosphere) has been extremely challenging.

Integrated photonic building blocks for next-generation astronomical instrumentation II: the multimode to single mode transition.

There are numerous advantages to exploiting diffraction-limited instrumentation at astronomical observatories, which include smaller footprints, less mechanical and thermal instabilities and high levels of performance. To realize such instrumentation it is imperative to convert the atmospheric seeing-limited signal that is captured by the telescope into a diffraction-limited signal. This process can be achieved photonically by using a mode reformatting device known as a photonic lantern that performs a multimode to single-mode transition.

Design of optically path-length-matched, three-dimensional photonic circuits comprising uniquely routed waveguides.

A method for designing physically path-length-matched, three-dimensional photonic circuits is described. We focus specifically on the case in which all the waveguides are uniquely routed from the input to output-a problem that has not been addressed to date and that allows for the waveguides to be used in interferometric measurements. Circuit elements were fabricated via the femtosecond laser direct-write technique.

Exceptional astronomical seeing conditions above Dome C in Antarctica.

One of the most important considerations when planning the next generation of ground-based optical astronomical telescopes is to choose a site that has excellent 'seeing'--the jitter in the apparent position of a star that is caused by light bending as it passes through regions of differing refractive index in the Earth's atmosphere. The best mid-latitude sites have a median seeing ranging from 0.5 to 1.

Adaptive-optics performance of Antarctic telescopes.

The performance of natural guide star adaptive-optics systems for telescopes located on the Antarctic plateau is evaluated and compared with adaptive-optics systems operated with the characteristic mid-latitude atmosphere found at Mauna Kea. A 2-m telescope with tip-tilt correction and an 8-m telescope equipped with a high-order adaptive-optics system are considered. Because of the large isoplanatic angle of the South Pole atmosphere, the anisoplanatic error associated with an adaptive-optics correction is negligible, and the achievable resolution is determined only by the fitting error associated with the number of corrected wave-front modes, which depends on the number of actuators on the deformable mirror.