INTUN Tunable Laser
12372-D02, 12/15/2007
Page 6
www.thorlabs.com
Part 3. System Description and Interfaces
This chapter is intended as an aid for designing a system that contains an INTUN TL-T. In order to
ensure that the INTUN TL-T will operate correctly and meet the stated specifications, requirements
regarding handling and operation stated within this manual must be met.
3.1. What is a Tunable Laser Source (TLS)?
A Tunable Laser Source (TLS) is a laser whose output wavelength can be swept (continuous or random
access) over a certain wavelength range. The INTUN TL-T laser’s tuning range typically varies from 3-
150 nm, depending on the model chosen. The TLS can be thought of as an optical equivalent to the
conventional electrical sweep oscillator. Although the acronym TLS is sometimes used interchangeably
with ECL (External Cavity Laser), ECL actually refers to the technical design of the laser itself.
Therefore, TLS encompasses a larger number of products than ECL since an ECL is not necessarily
tunable.
TLS’s are frequently used in various measurement applications to record some quantity (e.g., intensity)
as a function of wavelength. Each application requires detailed knowledge of some or all of the
parameters that characterize a TLS (e.g., wavelength range, side mode levels, spontaneous noise levels,
line width, sweep characteristics).
3.2. Brief System Overview
As shown in Figure 2, the INTUN TL-T is a TLS based on a semiconductor laser mounted in a Littrow
external cavity laser geometry. This tuning arrangement allows for high output power while maintaining
a large mode-hop-free tuning range.
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Figure 2: Schematic of the INTUN TL-T
The INTUN is based on a Littrow resonator: 1) diffraction grating, 2) intra-cavity collimating hybrid
(i.e., refractive and diffractive combination) achromatic lens, 3) laser diode, 4) output coupling optics
including an isolator, 5) optical fiber, and 6) motor.
