Laser Physics & Types Flashcards

Which laser type uses a mixture of helium and neon gases to produce a red beam at 632.8 nm?

Answer: He-Ne laser

The helium-neon (He-Ne) laser emits a characteristic red beam at 632.8 nm by exciting neon atoms via energy transfer from metastable helium atoms.

What is the term for the process in which an excited atom releases a photon spontaneously without external stimulation?

Answer: Spontaneous emission

Spontaneous emission occurs when an excited atom returns to a lower energy state and releases a photon without any triggering event.

In a semiconductor diode laser, what confines the light within the active region?

Answer: The p-n junction's refractive index difference

The difference in refractive index between the active p-n junction layer and the surrounding cladding layers creates a waveguide that confines light.

Which laser medium produces emission in the mid-infrared range and is widely used for cutting and welding metals?

Answer: CO2 laser

The CO2 laser emits at 10.6 µm in the mid-infrared and is highly absorbed by metals, making it ideal for industrial cutting and welding.

What property distinguishes laser light from ordinary white light in terms of phase relationship?

Answer: Coherence

Laser light is coherent, meaning all photons share the same phase, frequency, and direction, unlike the random phases of ordinary light.

The gain bandwidth of a laser medium determines which of the following?

Answer: The range of wavelengths over which lasing can occur

Gain bandwidth is the spectral range over which the medium provides net amplification, setting the possible lasing wavelengths.

Which of the following best describes a four-level laser system compared to a three-level system?

Answer: Its lower laser level is rapidly depopulated, lowering threshold

In a four-level system the lower laser level is quickly emptied by fast relaxation, so population inversion is easier to achieve and threshold pump power is lower.