Formal Invitation Letters

Persons who complete a registration and submit payment will be able to request an official invitation letter on workshop letterhead. The letter will be a PDF file delivered by email upon request per the instructions shown in the registration confirmation email. There is no additional cost for the emailed invitation letter.

If a hardcopy/physical invitation letter is required, you will be able to order one during the registration process. There is a fee associated with the hardcopy invitation, in order to cover the express-mail postage. This fee will be added to the registration total if you order the hardcopy express-mail invitation letter.

Authors of accepted papers can also request an "Official Acceptance Letter", which does not confirm registration, but does confirm that the paper is accepted into the technical program and invites the selected author to attend in order to give the paper presentation.

Official Invitation Letter for Registered Attendees

If you would like an invitation confirming registration on SLT 2016 letterhead in order to begin the travel-visa application process, you may request such a letter by clicking on the link below. Invitation Letters can be sent by email at no cost, or a hardcopy sent by express-post can be requested during registration. A fee is charged for the express-mailed invitation in order to cover the postage costs.

Request an Invitation Letter (confirming an existing registration)

Formal Acceptance Letter for Accepted Authors

If you would like a formal letter of acceptance on SLT 2016 letterhead in order to begin the travel-visa application process, you may request such a letter by clicking on the link below. Formal Acceptance Letters will be sent only by email.

Request a Formal Acceptance Letter (confirming an accepted paper)

Entry Requirements - Visas, Visa Waiver Program and ESTA

All international attendees must have a valid passport. We would like to advise all participants, who may be required to apply for a visa, that the application process requires time and may take up to a few months. Please visit the U.S. Department of State website for full visa acquisition information -

Participants under the Visa Waiver Program countries (see below) will still be eligible to travel without a visa, but will have to obtain an approved travel authorization prior to their travel to the U.S. (see ESTA information below).

Visa Waiver Program - Participating Countries as of March 10, 2014

Travelers coming to the U.S. for tourism or business for 90 days or less from qualified countries may be eligible to visit the U.S. without a visa, if they meet the visa waiver program requirements. Please visit the following website to learn more, and find out if you meet the visa waiver requirements - h Currently, 38 countries participate in the Visa Waiver Program.

New For International Visitors - ESTA

Electronic System for Travel Authorization (ESTA) - As of January 12, 2009, a valid ESTA approval is required for all Visa Waiver Program (VWP) to travel to the United States. The Department of Homeland Security, Electronic System for Travel Authorization (ESTA) is a free, automated system used to determine the eligibility of visitors to travel to the United States under the VWP. It collects the same information as the paper I-94 form that VWP travelers fill out en route to the United States. ESTA application may be submitted at any time prior to travel. An ESTA authorization generally will be valid for up to two years. Authorizations will be valid for multiple entries in the United States. DNS recommends that travelers submit and ESTA application as soon as they begin making travel plans. For further details about the new system, please visit the following website -

Please do not apply through a third-party website, which may not comply with ESTA regulations.