Fiber Optic Tutorials

This is a continuation from the previous tutorial - infrared and visible semiconductor lasers based on other material systems.   Introduction The performance of semiconductor lasers can degrade during their operation. This degradation is usually characterized by an increase in the threshold current that is often accompanied by a decrease in the external differential quantum efficiency. The dominant mechanism responsible for this degradation is determined by one or several of the fabrication processes including epitaxy, device processing, and bonding. In addition, the degradation rate of lasers processed from a given wafer depends on the operating conditions, namely, the operating temperature...

This is a continuation from the previous tutorial - Lead-Salt Semiconductor Lasers.   We focused our attention on lead-salt lasers in the previous tutorial. In this tutorial we briefly mention some of the results on semiconductor lasers obtained using material systems other than the lead salts.   1. Infrared Semiconductor Lasers The wavelength of semiconductor lasers has been extended to about 100 μm using single crystals of Bi1-xSbx solid solutions. By varying the composition x in the range of 0.08-0.16, the band gap of this material can be varied from 2.7 to 22.6 meV at T = 4.2 K. For the...

This is a continuation from the previous tutorial - optoelectronic integrated circuits (OEICs).   1. Lead-Salt Lasers In previous tutorials we paid particular attention to GaAs and InGaAsP semiconductor lasers that emit light in the wavelength range of 0.8-1.6 μm in view of their important applications in optical data storage and optical fiber  communications systems. However, longer-wavelength semiconductor lasers have also been of considerable interest and have found applications in molecular spectroscopy among other things, because of their large spectral tuning range. Figure 1-3 [refer to the the history of semiconductor lasers tutorial] showed the wavelength range covered by various material...

This is a continuation from the previous tutorial - Photonic Integrated Circuits (PIC).   The first OEIC was reported in the mid 1970s by Yariv and coworkers. It was a simple device - A Gunn diode integrated with a laser. Since then, various types of integrated laser-driver and photodiode-amplifier with single and multichannel capability have been reported. So far, most of the OEIC developments have been towards lightwave transmitters and receivers.   1. Receiver OEIC The receiver OEIC generally consists of PIN photodiode integrated monolithically with an amplifier.  The amplifiers using FET- and HBT-based technologies have been fabricated. The first...

This is a continuation from the previous tutorial - optical amplifiers.   During the 1980s and early 1990s, there has been a significant number of developments in the technology of optical and electronic integration of semiconductor lasers and other related devices on a single chip. These chips allow higher levels of functionality than that achieved with single devices. For example, lasers and electronic drive circuits have been integrated, serving as simple monolithic lightwave transmitters. Similarly, optical detectors have been integrated with amplifier circuits based on field-effect transistors (FETs) or heterojunction bipolar transistors (HBTs). Such integrated devices serve as the front...