Optical Communications, 2nd Edition

PROBLEMS

2.1 A point source transmitter at λ = 1μm transmits toward a circular lens of diameter 5 em, as shown in Figure P2.1. The source field at the lens has an intensity of 10⁻⁶ W/cm².

1. (a) Show approximately where the source will image in the focal plane shown.
2. (b) What is the peak intensity and diameter of the imaged Airy pattern?

Figure P2.1.

2.2 A field at λ = 1μm in a 1-mm diameter fiber core is a plane wave at the output. A lens matching the fiber diameter is inserted at the output to focus the fiber output field on to a detector located 2 mm from the fiber output. What is the minimal diameter of the detecting area to collect the main hump Airy pattern of the focused fiber field?

2.3 A square array of individual detectors, each 1 mm in diameter, is placed in the focal plane of a 50-cm receiver aperture.

1. (a) Estimate the resolution angle (radian field of view) of each detector.
2. (b) How large must the array be to cover an overall 2 degree by 2 degree field of view?

2.4 An optical receiver at λ = 1 μm uses a 3-in. aperture lens and a 1 cm detector.

1. (a) Estimate its diffraction-limited field of view.
2. (b) Estimate its receiver field of view.
3. (c) How many field modes (directions of arrival) can the receiver resolve?
4. (d) Approximately how far off the normal ax1s in angle can a point source be before it is not detectable?

2.5 Five lasers transmit a plane wave to an optical ...