CLT Laser Physics & Types 3

Question 1

What is the primary gain medium in an erbium-doped fiber amplifier (EDFA), and at what wavelength does it operate?

Accepted Answer

Er³⁺ ions at ~1550 nm

Answer

EDFAs use erbium ions (Er³⁺) doped into silica fiber and amplify signals near 1550 nm, which coincides with the low-loss window of optical fiber.

Question 2

In a Q-switched laser, what happens when the Q-switch opens?

Accepted Answer

Cavity loss suddenly drops, releasing stored energy as a short intense pulse

Answer

Opening the Q-switch removes the artificially high intracavity loss, causing the large stored population inversion to deplete rapidly as a high-peak-power pulse.

Question 3

Which laser type uses an organic dye dissolved in a solvent as the gain medium?

Accepted Answer

Dye laser

Answer

Dye lasers use fluorescent organic dyes in liquid solution as the gain medium and are tunable over a broad wavelength range.

Question 4

What does the term 'TEM₀₀ mode' indicate about a laser beam?

Accepted Answer

The beam has a Gaussian intensity profile with the smallest beam waist

Answer

TEM₀₀ is the fundamental transverse electromagnetic mode, characterized by a Gaussian profile and the lowest beam divergence for a given aperture.

Question 5

Excimer lasers produce UV radiation by using which type of gain medium?

Accepted Answer

Unstable noble-gas halide molecules

Answer

Excimer lasers use excited dimers or exciplexes—bound excited states of noble-gas halides like ArF or KrF—that dissociate after emitting a UV photon.

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(CLT) Certified Laser Technician Practice Test

CLT Laser Physics & Types 3