The RP Photonics Encyclopedia

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This comprehensive open-access encyclopedia, authored by Dr. Rüdiger Paschotta and provided by RP Photonics Consulting GmbH, covers much of the areas of optics and photonics. In particular, it explains the physical principles and techniques in laser technology, while also covering major areas of fiber-optic technology and nonlinear optics, and addressing supplementary topics like ultrashort pulses, optical communications, optoelectronics and quantum optics. It contains 890 full articles – not only definitions as in a dictionary or a glossary. Many references to selected scientific articles and textbooks aid further studies. Substantial work has been invested and is further invested to provide all information with advanced textbook quality. With this work, RP Photonics provides a much appreciated service to both the photonics industry and the academic community.

The encyclopedia is freely accessible via this website – without registration, and with full privacy. Simply click on one of the letters in the table above in order to display the keywords beginning with that letter. For conveniently finding this resource again, please bookmark the page in your browser.

The encyclopedia has also become available as a two-volume book, published via Wiley-VCH in 2008. The print version has a carefully designed layout and can be considered a must-have for any institute library, laser research group, or laser company.

Since mid 2012, the encyclopedia is intimately linked with the RP Photonics Buyer's Guide, a resource for finding suppliers of optics and photonics products.

Dr. Rüdiger Paschotta, the author of the encyclopedia, offers a broad range of consulting services in topical areas like lasers, amplifiers, nonlinear optics and fiber optics via RP Photonics. Utilize his competence for your development projects, or for a tailored staff training course for your company! Also, you may be interested in the simulation software which he has developed.

Besides the encyclopedia articles, there are related pages, which you can reach via the menu on the top of this page:

• Grouping of the articles into categories
• Glossary of photonics terms and list of formula symbols
• RP Photonics Buyer's Guide, the ideal place for informing experts on photonics products
• The Photonics Spotlight, a blog with interesting news in photonics and laser technology (also available as a newsletter)
• The Photonics Quiz with a number of questions on lasers and related areas
• Opportunities for advertising in the encyclopedia
• Suggestions concerning the use of the encyclopedia
• Hints for making links on your own web page and for citing encyclopedia articles
• Feedback: send comments and suggestions to RP Photonics

Here you can get an overview on the topics which are covered by this encyclopedia.

• General optics: geometrical optics, imaging, optical aberrations, entrance and exit pupil, Kramers–Kronig relations, Fourier spectrum, Gaussian beams, Hermite–Gaussian modes, Gouy phase shift, beam quality, brightness, optical resonators, waveguide dispersion, finesse, coherence, phase velocity and group velocity, superluminal transmission and causality
• Optical instruments and devices: photo cameras, loupes, microscopes, telescopes, interferometers, Bragg mirrors, beam shapers, optical filters, electro-optic modulators, acousto-optic modulators, optical tweezers, arrayed waveguide gratings, integrating spheres, mode cleaner cavities, Lyot filters, optical spectrum analyzers
• Optoelectronics: photodiodes, avalanche photodiodes, phototransistors, photocathodes, photomultipliers, photon counting, laser diodes, quantum cascade lasers, light-emitting diodes, superluminescent diodes, photonic integrated circuits, silicon photonics, electroabsorption modulators, opto-isolators, image sensors
• Nonlinear optics: nonlinear crystal materials, intracavity or resonant frequency doubling, sum and difference frequency generation, optical parametric oscillators, parametric generators and amplifiers, Brillouin and Raman scattering, self- and cross-phase modulation, four-wave mixing, quasi-phase matching
• Fiber optics: high power fiber lasers and amplifiers, Raman amplifiers, single-mode and multi-mode fibers, rare-earth-doped fibers, double-clad fibers, dispersion-shifted fibers, photonic crystal fibers, fiber Bragg gratings, adiabatic soliton compression, nonlinear polarization rotation
• Lasers and amplifiers: laser design and development, laser resonators, laser and amplifier noise, erbium-doped fiber amplifiers, broad area laser diodes, fiber-coupled diode lasers, diode-pumped lasers, fiber lasers and amplifiers, power scaling, distributed feedback lasers, upconversion, gain media, amplified spontaneous emission, beam pointing fluctuations, single-frequency operation, spatial hole burning, relaxation oscillations, red, green and blue lasers, cryogenic lasers, laser modeling, beam quality, laser safety, laser specifications
• Light pulses: bandwidth-limited pulses, parabolic pulses, mode-locked lasers, additive-pulse mode locking, regenerative amplifiers, chirped-pulse amplification, transform limit, pulse characterization, time–bandwidth product, frequency combs, timing jitter, pulse duration measurements, Kelly sidebands, parabolic pulses, Q-switched lasers
• Optical communications: optical fiber communications, fiber-optic links and networks, telecom windows, free-space optical communications, space division multiplexing, amplifier noise, bit error rate, bandwidth–distance product, optical modulators, photonic integrated circuits
• Optical spectroscopy: laser absorption spectroscopy, time-resolved spectroscopy, Raman spectroscopy, multipass gas cells, spectrometers, spectrophotometers, tunable lasers, mid-infrared laser sources
• Quantum optics and quantum effects: squeezed states of light, Glauber states, quantum wells, quantum dots, light forces, laser cooling, quantum noise, shot noise, Schawlow–Townes linewidth, quantum cryptography
• Noise in optics: noise specifications, power spectral density, timing jitter, Gordon–Haus jitter, quantum noise, squeezed states of light, standard quantum limit, shot noise, relative intensity noise, phase noise, noise eaters, linewidth, stabilization of lasers

This encyclopedia is not a static resource, but is constantly further extended to cover more topics and more details. Here you find the latest articles:

• retardance
• microlens arrays
• Shack–Hartmann wavefront sensors
• quantum photonics
• deformable mirrors
• fluorescence spectroscopy
• wavefronts
• Berek compensators
• Babinet–Soleil compensators
• common-path interferometers
• liquid crystal modulators
• liquid crystal displays
• dichroism
• pulse shapers
• first surface mirrors
• electro-optics
• optical tables
• optical breadboards
• tapered laser diodes
• high brightness laser diodes

See also: RSS-Feed for new articles

The following encyclopedia articles have recently been substantially improved:

• optics
• achromatic optics
• numerical aperture
• polarization of light
• beam splitters
• lenses
• laser microscopy
• optical power meters
• resonator design
• resonant frequency doubling
• photomultipliers

Here are some randomly selected articles – just to make you curious:

• optical modulators
• objectives
• nonlinear polarization
• collimated beams
• nodal points
• tapered amplifiers
• modal bandwidth
• fiber-coupled diode lasers
• vertical cavity surface-emitting lasers
• reflectivity
• bend losses
• principal dispersion
• fiber launch systems
• object and image space
• saturable absorbers
• optical data transmission
• optical metrology
• bandwidth–distance product
• fluoride glasses
• ultrafast lasers

Note that articles from the Photonics Spotlight and the RP Software News are not listed here; check them separately!