Calculate critical angel and fundamental gaussian mode, Electrical Engineering

(1) An argon ion laser, emitting light at a wavelength of 488nm with a beam divergence of 150 firad, is used to illuminate the moon.

(i) Assuming the earth-to-moon distance is 3:8_108 m, estimate the diameter of the spot on the moon.

(ii) Calculate the waist of the beam in the laser, assuming that the beam is a fundamental Gaussian mode.

(iii) Suggest a way by which the spot diameter on the moon could be reduced by a factor of 100.

(2) The bandgap of GaAs is 1.4 eV.

(i) Calculate the probability of a valence electron being in the conduction band by thermal excitation at 0°C.

(ii) The donor binding energy in GaAs is 5.8 meV. Calculate the probability of finding a donor electron in the conduction band at 0°C.

(iii) From an electronic point of view, what is the difference between undoped and n-type GaAs?

(3) An optical fibre has a core refractive index of 1.52, and a numerical aperture of 0.12.

Calculate its:

(i) Critical angle.

(ii) Cladding refractive index.

(iii) Maximum acceptance angle in (a) air, and in (b) water (refractive index =1.3)

(4) (i) What is the primary reason that optical fibres are used for communicating information?

(ii) How can you maximise the amount of information transmitted?

(iii)Estimate the bandwidth of a fibre of core diameter 50°m, n1 = 1:50, n2 = 1:49, and length L = 50 km.

(iv) Identify 2 other things that optical fibres are useful for.

(5) The mean power launched into an optical fibre of length 10 km is 150 _W and the average power at the output is 5°W. Calculate the overall attenuation in dB, and the attenuation per kilometre, assuming there are no interface losses.

Each question is worth ten points.

Posted Date: 3/16/2013 5:17:03 AM | Location : United States

Related Discussions:- Calculate critical angel and fundamental gaussian mode, Assignment Help, Ask Question on Calculate critical angel and fundamental gaussian mode, Get Answer, Expert's Help, Calculate critical angel and fundamental gaussian mode Discussions

Write discussion on Calculate critical angel and fundamental gaussian mode
Your posts are moderated
Related Questions
Execution of Digital Logic Circuits A safety circuit is employed on a lathe to prevent the motor turning if it is not safe to operate. A series of 2 switches are used to check

Mention the categories of instruction and give two examples for each category The instructions of 8085 can be categorized into the following five Data transfer MOV Rd,Rs

Q. Show Applications for DC Machines? Dc motors find wide applications in which control of speed, voltage, or current is essential. Shunt motors with constant speed are used fo

Construction - UniJunction Transistor: Construction: The basic structure of uni junction transistor is shown in fig. (a). It essentially consists of a lightly doped N type s

Mutual inductance and coefficient of coupling: The equivalent inductance of two series connected coil (with mutual inductance among them) is 0.8 or 0.2 Henry based on the rela

Q. The external - characteristics data of two shunt generators in parallel are given as follows: Load Current, A: 0 5 10 15 20 25 30 Terminal voltage I, V: 270 263 254 240 22

Q. Explain the conditions to be satisfied for sustained oscillations in an oscillator circuit with the help of block diagram. The essential condition for sustained oscillations

can I get matlab code for out of band radiation reduction ofdm system

The Three-phase alternator In this case, three separate sets of coils are wound on the stator and connected to produce three separate outputs. Because of the physical displace

Q. For an RG-290/U aluminum rectangular wave - guide, a = 58.42 cm and b = 29.21 cm. Compute the theoretical and practical frequency ranges of operation for the guide.