Frequently Ask Questions (FAQ)

Can fiberdesk be used for ns pulses or CW light?

In principle, the nonlinear Schrödinger equation permits the propagation of long pulses. However, Brillioun scattering is not implemented. Raman scattering can be simulated. For cw light, the repetition rate has to be set according the temporal dimensions so that the peak and average powers equal. From fiberdesk 5, this is a feature of the "create pulse" dialog offering "cw" option, which automatically equalizes repetition rate to the temporal window.


Additionally, one has to keep in mind that the spectral bandwidth is given by the temporal resolution (time window over number of datapoints). For instance, for the maximum number of datapoints a 80 ns pulse with an bandwidth of ~100 nm @ 1µm central wavelength can be handled, with the drawback of being very slow. Additionally, without the NLSE, ns and cw light can be used in the rate equation simulations provided by fiberdesk.

What to do if the software does not start or an error occurs due to the protection USB stick?

USB dongles after 2020 do not need to have a driver installed, it comes automatically with MS Windows.

However, if the USB dongle driver need to be installed, for instance, to access the information page required by the next FAQ, please do the following steps:


0. Remove the USB Stick and Start your computer with administration rights

1. download the Sentinel HASP/LDK - Command Line Run-time Installer at

2. please unzip and start the containing file haspdinst.exe from the command line to uninstall all previous drivers completely by:

   haspdinst -purge

3. again, from the command line, install the new driver by

   haspdinst -install

4. Insert the USB Stick and start fiberdesk


If you still have problems, contact the fiberdesk support including the reference to your license version.

You still get an error message?

Please use http://localhost:1947 in your web browser and send the screenshot or feature number of the key to the official fiberdesk email address.

If http://localhost:1947 is not running, please install the driver mentioned in the previous answer. 

fiberdesk does not start even when the USB dongle is working correctly. What can I do?

Firstly, please take a look in the folder


and send the file "_fiberdesk_0.log" to the support.

Additionally, please start fiberdesk from the command line (Windows Key and then type "cmd"+Enter, change to the fiberdesk folder and start fiberdesk). Then, please send a screenshot of the command line output to the support, see example in the picture.

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