Short address: rpp-con.com
Dr. Paschotta, the founder of RP Photonics, supports your R & D with his deep expertise. Save time and money with efficient support!
Short address: rpp-soft.com
Powerful simulation software for fiber lasers and amplifiers, resonator design, pulse propagation and multilayer coating design.
Short address: rpp-enc.com
The famous Encyclopedia of Laser Physics and Technology provides a wealth of high-quality scientific and technical information.
Short address: rpp-bg.com
In the RP Photonics Buyer's Guide, you easily find suppliers for photonics products. As a supplier, you can profit from enhanced entries!
Learn on lasers and photonics every day!
||part of the|
In the RP Photonics Buyer's Guide you can find plenty of suppliers for hundreds of photonics products.
Definition: the minimum pulse duration possible for a given optical spectrum
In ultrafast optics, the transform limit (or Fourier limit, Fourier transform limit) is usually understood as the lower limit for the pulse duration which is possible for a given optical spectrum of a pulse.
A pulse at this limit is called transform limited.
The condition of being at the transform limit is essentially equivalent to the condition of a frequency-independent spectral phase (which leads to the maximum possible peak power), and basically implies that the time–bandwidth product is at its minimum and that there is no chirp.
The minimum time–bandwidth product depends on the pulse shape, and is e.g. ≈ 0.315 for bandwidth-limited sech2-shaped pulses and ≈ 0.44 for Gaussian-shaped pulses.
(These values hold when a full-width-at-half-maximum criterion is used for the temporal and spectral width.)
For a given pulse duration, transform-limited pulses are those with the minimum possible spectral width.
This is important e.g. in optical fiber communications: a transmitter emitting close to transform-limited pulses can minimize the effect of chromatic dispersion during propagation in the transmission fiber, and thus maximize the possible transmission distance.
Many mode-locked lasers, particularly soliton lasers, are able to generate close to transform-limited pulses.
During propagation e.g. in transparent media, phenomena such as chromatic dispersion and optical nonlinearities can cause chirp and thus can lead to non-transform-limited pulses.
Such pulses may be brought back to the transform limit (and thus temporally compressed) by modifying their spectral phase, e.g. by applying a proper amount of chromatic dispersion.
This is called dispersion compensation.
For not too broad spectra, compensation of second-order dispersion is often sufficient, whereas very broad spectra may require compensation also of higher-order dispersion in order to approach the transform limit.
See also: spectral phase, pulse duration, time–bandwidth product, dispersion, dispersion compensation, Spotlight article 2007-10-11, Spotlight article 2008-06-13
Have you seen the
RP Photonics Buyer's Guide?
It lists many hundreds of suppliers for photonics products, and is just one mouse click away from the extremely popular Encyclopedia of Laser Physics and Technology:
- In any product-related encyclopedia article, you find a box for the Buyer's Guide.
- Alternatively, click on the heading which your mouse pointer has just touched.
Our Buyer's Guide is what you need:
- easy handling, clear layout
- high-quality information
- additional technical information in the encyclopedia
And surely you will remember where to find this useful resource again!
Suppliers: get your free entries, and enhanced visibility with paid entries.
Free Fiber Optics Software!
RP Fiber Calculator – a convenient tool for calculations on optical fibers -- offered for free –
let us celebrate the 10-year anniversary of RP Photonics!
RP Photonics Buyer's Guide
Do you know a better place to find suppliers for photonics items?
Search by product or by supplier.
Suppliers, show your products with free or enhanced entries!
The Encyclopedia in Book Form
The two-volume print version of the encyclopedia would deserve a place in your institute or group library!
Click on the image to get to Wiley-VCH.
Laser Design Services
Fast and efficient laser development is possible with the competent design services of RP Photonics, based on extensive experience, deep scientific knowledge and advanced software.
Understand your devices, avoid wasting resources, minimize time to market!
Get into efficient modeling with RP Photonics software or utilize advanced technical expertise via consultancy.