Using free space optics research to teach optics and optoelectronics

Free space optics research encompasses a variety of optics and optoelectronics concepts making it an ideal educational venue. The research and development of a free space optics wireless link was used to teach optics and optoelectronics to undergraduate students. Essential to the educational component in the experiment was an actively mode locked ultrashort pulse laser system, designed for telecom research, which offered a clear visual correlation between the optically modulated data signal, displayed on a digital communication analyzer, and the received electrical signal, obtained by an Indium Gallium Arsenide detector, displayed on an oscilloscope. Data patterns generated by a bit error rate tester were modulated onto the laser using a Mach Zehnder Modulator. Optical taps on the laser allowed the students to view the mode locking of the laser and the output signal from the modulator. Both taps were crucial for teaching the students how changes made to the laser cavity, effect the performance of the laser and the modulated output. At the receive end of the link, students learn how the optical signal is transmitted, detected and converted from an optical signal to an electrical signal via the detector. The students can view the received data pattern on an oscilloscope and compare it to the transmitted data pattern. Using the error detector on a bit error rate tester, the students can also determine the bit error rate. This free space optics research project supports course instruction for optics courses, optoelectronics courses and undergraduate research.