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Legal and Contact Information

Here you can find basic data on RP Photonics AG.

This page serves as an imprint, also for the following social media:

(We are no longer on Facebook and Twitter/X, as these are not compatible with our ethical standards.)

Contact Information

Mail address: RP Photonics AG
Bannhaldenstr. 38
8500 Frauenfeld
Note: We have moved to Switzerland in February 2022! The business is now done by the new Swiss company which we founded there. (The previous German company was: RP Photonics Consulting GmbH, Waldstr. 17, D-78073 Bad Dürrheim, trade register number HRB 706010, Amtsgericht Freiburg i. Br.; it is going to be liquidated.)
Managing director: Dr. Rüdiger Paschotta (also responsible for any content of the website; same postal address as the company)
Telephone: +41 52 720 8000
You can normally reach us 09:00 – 13:00 and 14:00 – 18:00 (central European time). For American customers: we are 6 h ahead of Eastern Time and 9 h ahead of Pacific Time.
Mobile phone: on request

For issues related to the RP Photonics Buyer's Guide, please use the following address:

Incoming e-mails are subject to “gray listing”, a spam filtering technique. In rare cases, where a server sending e-mails is not properly configured, this can cause technical problems; please use the phone in such a case.
You are encouraged to establish secure e-mail exchange for protecting your sensitive information!
In case that you have a problem with replying to digitally signed mails, just mail to our info@ address.
Video chat: We can arrange a contact via Skype,, Teams or Zoom. Please first make an appointment.
FTP: If you need to exchange larger amounts of data (more than a few megabytes) with RP Photonics, an FTP account can be provided.

Please also see our page on privacy.

Various Data

UID (company ID): CHE-141.173.265

Mass Mails and Fraudulent Mails from RP Photonics?

Occasionally, large amounts of spam (unwanted mass mails), phishing attempts and similar kinds of fraudulent mails are spread which are falsely claiming an e-mail address in the domain as the sender, sometimes even the sender address of the managing director. Some of those mails have attachments containing malware, and others try to make you click on a dubious link. Obviously, behind such activities there are criminals who try to gain trust from possible victims by pretending that their mails are from RP Photonics, a reputable source. Some of them are also abusing our company logo and further data, e.g. our telephone number.

Note that mails are never sent through our mailserver. Instead, criminals use their own mail server, on which we have no control whatsoever, and simply claim our domain to be the sender (e-mail spoofing). Unfortunately, the basic e-mail standards allow that without any checks. (By the way, our servers have so far never been hacked; we protect them very carefully.) However, there are several mechanisms which allow receiving mail servers to check for such abuse:

  • An SPF record, published through our domain (in the domain name system DNS), indicates that legitimate mails from RP Photonics are all sent through a server of our hoster. In other words, mails coming from other mail servers are all illegitimate, not from us.
  • Since October 2023, all our mails are digitally signed with DKIM. That certificate, when properly validated, proves (a) that the mails are from our server and (b) that they have not been modified on the way. In other words, any mails without a valid DKIM certificate cannot be from us.
  • Further, we have published a DMARC record, instructing receiving mail servers to strictly check SPF and DKIM, and reject all mails not passing both tests.

Therefore, you should no longer receive illegitimate mails abusing our domain, provided that your mail server is properly set up to make the mentioned tests. For any reasonable provider, that should be the case.

For the case that anything dubious still gets through, we can give some indications for checking whether such mails are from us:

  • Our mails are all properly formatted, written with decent language etc.; the style is usually very different from what spammers typically use. Fortunately, spammers normally invest very little time into optimizing such mails; they are mostly targeting easy victims, who do not critically check what to accept. However, that might soon change since fraudsters are starting to use artificial intelligence.
  • Of course, RP Photonics is never sending out mails concerning items which are totally unrelated to its business. However, some abuse has also happened in the context of photonics.
  • All our mails strictly come from the domain only, never e.g. from Gmail.
  • Messages from Dr. Paschotta, the founder and managing director of RP Photonics, and also those from (but not our newsletter mailings) are always digitally signed; the signature can be validated by your e-mail program and then confirms that a mail is really from the claimed sender.
  • RP Photonics may occasionally ask you to click on a link in our domain (, e.g. to view one of our web pages such as an encyclopedia or blog article, but not on dubious other domains.
  • In case of doubt, just forward such an alleged RP Photonics message to us, and we will tell you whether it was from us.

Please do not put our addresses or our domain on any e-mail blacklist. Indeed, you should be safe putting them on any e-mail whitelist, assuming that your mail server properly does the usual tests.