Prof. F. Martinache & Nick Cvetojevic
|Experimental Interferometric Recombination with Astro-photonics|
(S2, elective, 3 ECTS)
|Learning Outcomes:||State of the art photonic technologies can control, route, and manipulate light at microscopic scales with unprecedented precision. This new technology has been used to great effect to rev-olutionise broadband telecommunication networks, develop non-invasive biomedical sensing, and even used to create quantum-computing chips. Now this powerful tool is becoming an integral part of astronomical instrumentation, providing functionality not previously possible with traditional optics. From simple fiber-optics to advanced on-chip light circuits, this course will provide theory and hands-on experience with the future of astronomical instrumentation.|
|Knowledge and Understanding:||Students taking the Astrophotonics lecture will become competent in a wide range of photonic technologies that are currently used in astronomy. These include standard photonic devices such as optical fibers, optical waveguides, lasers, laser frequency combs, and photonic crystals, as well as more com-plicated devices designed for as-tronomical use such as photonic lanterns, pupil remappers, andon-chip interferometers. They Will also become familiar with the unique ways these devices are integrated into astronomical instrumentation. Photonic technologies bend and manipulate light on fundamental scales. In addition to learning about the theory of photonic devices and astronomical instrumenta-tion, students will gain hands-on experience in the KERNEL-laboratory working with ad-vanced interferometric photonic chips. They will gain real-world experience working with lasers,deformable mirrors, optical fi-bres, spectrographs, integrated waveguide circuitry, and on-chip thermo-optic modulation.|
|Applying Knowledge and Understanding:||Students taking the Astropho-tonics lecture will become competent in a wide range of photonic technologies that are currently used in astronomy.These include standard photonic devices such as optical fibers, optical waveguides, lasers, laser frequency combs, and photonic crystals, as well as more com-plicated devices designed for as-tronomical use such as photonic lanterns, pupil remappers, andon-chip interferometers. They Will also become familiar with the unique ways these devices are integrated into astronomical instrumentation.|
|Prerequisites||General Astrophysics, Fourier optics|
|Program||THEORY: When light is focused and con-fined in a small area, and begins to interact with materials on mi-croscopic scales, a different language of electro-magnetism needs to be used to better understand what’s happening. The framework of lightrays used to explain traditional op-tics (lenses/mirrors), gives way to dis-cussing ’mode-structure’ and ’photonic band-gaps’ at these scales. For mod-ern state-of-the-art astronomical in-strumentation, understanding this the-oretical background is becoming criti-cal.At microscopic scales the modalnature of light propagation becomesimportant.As part of this course, students will get an introduction to the underlying theoretical framework that underpins the microscopic guiding of light, includ-ing waveguiding theory, mode theory,and photonic structures. In addition,we will cover the creation and manip-ulation of coherent sources, including laser fundamentals and nonlinear optics, from an astronomical instrumen-tation perspective. Building on this, students will get an overview of how these technolo-gies are used in the context of state-of-the-art astronomical instrumenta-tion. These include Multi-Object Wide-Field Spectrographs, Laser guide star & Adaptive Optics, Laser frequency combs & high-resolution spectroscopy,High-angular resolution & long baseline interferometry. While not exhaustive, this course will provide a high-level overview to the theory behind the operation of a wide array of photonic technology|
APPLICATIONS: The Kernel Nulling photonic chip the students will characterize.During the second-half of this course, students will take part in the characterization of a new astrophotonics device in the KERNEL laboratory.This photonic-chip is a novel kind of interferometer, called a ’Kernel-Nuller’, which enables high-contrast and high-resolution imaging of exoplan-ets. The chip contains photonic waveg-uides, beam-combiners, and thermo-optic phase controllers, whose proper-ties must be measured before deploy-ment on a telescope.Students will use the photonic char-acterization bench to probe and mea-sure the chip. They will learn how to operate lasers safely, the fundamentals of wavefront control, how to efficiently couple light into waveguides and fibers,and how to measure key properties of an astronomical interferometer. In ad-dition, they will gain real-world experi-ence operating high-precision multi ax-ial alignment stages, a skill which is in-tegral to working with photonic devices.Students will keep a comprehensive lab book to track their experiments and progress, and will learn how to analyze and present experimental data.
|Description of how the course is conducted||In addition to learning about the theory of photonic devices and astronomical instrumenta-tion, students will gain hands-on experience in the KERNEL-laboratory working with ad-vanced interferometric photonic chips. They will gain real-world experience working with lasers,deformable mirrors, optical fi-bres, spectrographs, integrated waveguide circuits, and on-chip thermo-optic modulation.|
|Description of the didactic methods||Theory and practise|
|Description of the evaluation methods||The theoretical part will be controlled by an oral exam.|
The laboratory characterization will culminate in an oral presentation by the students explaining the measured results.