The configuration of the distributed feedback dye laser (DFDL) system is shown in Fig. 1, and consis — Physical Chemistry Chemistry Question
Spectral Analyzer
The configuration of the distributed feedback dye laser (DFDL) system is shown in Fig. 1, and consists of an oscillator and a preamplifier.
The oscillator is made of a quartz cuvette (dye cell–1) equipped with a dye circulation pump. The detailed construction of the oscillator is shown in Fig. 2.
[VISUAL]
Two laser beams (λP = 355.00 nm) are reflected by two rotating dielectric mirrors and subsequently focused onto the dye solution to form an interference pattern, the spacing of which determines the wavelength of the laser emission. The wavelength of the laser emission, λDFDL, can be calculated using the following equations:
λDFDL = 2 n Λ
Λ = λP / (2 sin θ)
where n is the refractive index of the medium; Λ, the fringe spacing; and θ, the angle from the normal surface. The laser wavelength can also be determined from the fringe spacing, which, in turn, can be determined from the angle of incidence of the pump beam. The DFDL beams come from two sides of the cell. The wavelength of the DFDL can be measured by a Wavemeter. The power of the DFDL can also be amplifier by passing it through a preamplifier (the second dye cell; dye cell–2).
What would be the wavelength of the DFDL when the angle of θ is 60.00 and the refractive index of the medium is 1.40?
(a) 374 nm
(b) 474 nm
(c) 574 nm
(d) 674 nm
(e) 774 nm
Model Answer
Option (c) 574 nm.
Solution:
Λ = 355.00 / (2 * sin 60.00) = 204.96 nm
λDFDL = 2 * n * Λ = 2 * 1.40 * 204.96 = 573.89 nm (rounds to 574 nm)