Optics and Photonics Selim Jochim together with Dr. K. Simeonidis MPI für Kernphysik und Uni Heidelberg Email: selim.jochim@mpi-hd.mpg.de k.simeonidis@mpi-hd.mpg.de Website for this lecture: www.lithium6.de  teaching

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 in Heidelberg: 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: 11.4. Geometric optics, rays (Fermat’s principle) 18.4. No class 25.4. Wave optics, gaussian beams (paraxial Helmholtz eq.) 2.5. Polarization optics, optical coatings, wave guides, … 9.5. Atom-photon interaction 16.5. Lasers: Light amplification 23.5. Laser oscillation, optical resonators

Contents II 30.5. More lasers, solid state lasers, dye lasers, etc. 6.6. Pulsed lasers: Q-switching, mode locking, extremely short pulses 13.6. Semiconductor photonics: detectors, LEDs, Lasers 20.6. Fourier optics, holography 27.6. Nonlinear optics concepts 4.7. Nonlinear optics applications: Frequency doubling, mixing .. 11.7. Advanced applications: Frequency comb, optical synthesizer ... 18.7. Lab tour(s)

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

1. 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 Fermat’s principle: “Minimize” optical path length:

Fermat’s principle Phenomenologically: Hero of Alexandria (ca. 70 – 10 A.D.): Light always takes the shortest path when reflected from a surface:

Refraction A Zeichung B

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

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

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

Spherical mirror, paraxial rays Paraxial rays: Assume that all beams propagate “close” to optical axis. In most cases, this means that sin q≈ tan q ≈ q Rays are focused to F=R/2

Imaging with spherical mirrors

Thin lenses

Paraxial imaging Magnification

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 ….

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

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   All kinds of quality grades available Molded, plastic material

Precision machined … ASPHERIC LIMITS STANDARD HIGH PRECISION   STANDARD HIGH PRECISION Diameter (mm) 15-120 Length (mm) 10.5-85 Width (mm) Dimensional Tolerances (µm) 25 5 Center Thickness Tolerance (µm) 100 35 Wedge Tolerance (µm) 75 Surface Quality 60-40 10-5 Radius Limits (mm) LRC Limited Concave >30.0 Convex >5.0 Radius Tolerance (%) 0.1 0.05 Total SAG (mm) <25 Aspheric Surface Accuracy (wave)   1/4 1/10