An optical fiber with a step-index profile has a core with a diameter of 4 µm. The core and shell indexes are approximately equal (¹~¹₂), and the difference between them, An=n-₂, is such that An/n, = 2%. Find the minimum wavelength inside the core, ^=¹/¹, for which the fiber operates as a single mode.

Problem 3. A Fabry-Perot laser cavity is made of two identical mirrors. Each miror has an optical power reflectance R=0.999. The distance between the two mirrors is d=10 cm. The laser cavity is filled a gas material as the gain medium with an index of refraction n=1.05. (a) What is the photon life time of this laser cavity? (b) In order to make a laser using this cavity, you need to pump the gain medium to have a gain for compensating the losses at two mirrors. What is the threshold gain coefficient for this laser?

Compute the 2(theta) values for the first 3 x-ray diffraction peaks of a BCC metal with an atomic radius of 0.19 nm. The x-ray wavelength is 0.17 nm.

The active volume of a laser constructed of the semiconductor GaAlAs is only 200 mm3 (smaller than a grain of sand), and yet the laser can continuously deliver 5.0 mW of power at a wavelength of 0.80 mm.At what rate does it generate photons?