Optics and Photonics Selim Jochim MPI für Kernphysik und Uni Heidelberg Website for this lecture:

What will you learn in this course? How to use advanced photonics instruments and technology in the laboratory Learn to develop your own ideas on how to make use of photonics for (precision) experiments Knowlegde that is widely needed in many labs here: –Biomedical research –Laser spectroscopy –High-power ultrafast lasers for atomic physics –Laser cooling and trapping, (quantum) manipulation of atoms, molecules or ions

Motivation We make (increasingly) heavy use of photonics in our daily life: Two interesting examples: Green laser pointers emit bright light at 532 nm: How are they made? make use of almost anything you will learn in this course!! DVD reader/writer ( resolution of a microscope for a few !!)

Contents Preliminary list: geometric optics, rays wave optics, gaussian beams, 4.5. fourier optics, holography Polarization, linear, circular birefringence Optical coatings, wave guides, fibers Atom-photon interactions

Contents II 1.6. Lasers: principle, optical resonators, eigenmodes 8.6. More lasers, solid state lasers, dye lasers, etc Pulsed lasers: Q-swtiching, mode locking, extremely short pulses Semiconductor photonics: detectors, LEDs, Lasers Nonlinear optics concepts

Contents III 6.7. Nonlinear optics applications: Frequency doubling, mixing Advanced applications: Frequency comb, optical synthesizer accoustooptical and electrooptical tools: AOM EOM etc Reserved for special topics, extra time that certain subjects may require

Recommended literature Davis: Lasers and Electro-Optics: Fundamentals and Engineering Saleh, Teich: Fundamentals of Photonics Demtröder: Laserspektroskopie Hecht, Optics (Especially the first few lectures)

Geometric (ray) optics Light propagates as rays with speed of light, c in vacuum In a medium, the light is slowed down by the refractive index n In an inhomogeneous system, propagation is governed by Fermats principle: Minimize optical path length:

Reflection and Refraction Easily derived from Fermats principle

Parabolic mirror Parallel beams are focused onto a single spot: Car headlight!

Spherical mirror Paraxial rays: Close to optical axis, rays will be focused to F=R/2

Imaging with spherical mirrors

Thin lenses

Paraxial imaging Magnification

Interfaces between dielectrics … n2>n1 … Total internal reflection …. critical angle:

Where total internal reflection is used Prisms, e.g. binoculars, camera viewfinder Optical fibers:

Matrix formalism for parax. rays Use it to describe a complex optical system with a single (2,2)-matrix Define state of a ray by a 2-comp. vector: valid if

Example matrices Free space propagation Refraction at a surface

Optical system ….

Where the paraxial approx. fails … Focussing of a laser beam: Minimize non-paraxial distortions: Plano-convex lens, also best form lens

Spherical aberration … Can we make all parallel rays incident on a lens end up in a single spot??

Aspheric lens? Optical path length should be the same for all angles ….

Aspheric lenses All kinds of quality grades available Molded, plastic material

Precision machined … ASPHERIC LIMITS STANDA RD HIGH PRECISIO N Diameter (mm) Length (mm) Width (mm) Dimensional Tolerances (µm) 255 Center Thickness Tolerance (µm) Wedge Tolerance (µm) 7525 Surface Quality Radius Limits (mm) LRC Limited Concave >30.0 Convex >5.0 Radius Tolerance (%) Total SAG (mm) <25 Aspheric Surface Accuracy (wave) 1/41/10