Fiber Optic Tutorials

This is a continuation from the last tutorial - Timing Synchronization in Coherent Optical Transmission Systems.   1. INTRODUCTION The electro-optic effect is one of several means to impose information on, or modulate, a light wave carrier. Electro-optic devices have been developed for application in communications , analog and digital signal processing, information processing, optical computing, and sensing. Example devices include phase and amplitude modulators, multiplexers, switch arrays, couplers, polarization controllers, deflectors, Givens rotation devices, correlators, A/D converters, multichannel processors, matrix-matrix and matrix-vector multipliers, and sensors for detecting temperature, humidity, and radio frequency electrical signals. The electro-optic effect allows for...

This is a continuation from the previous tutorial - an introduction to optical beams and resonators.   1. Introduction A fundamental building block of modern coherent optical transport system is the timing recovery or timing synchronization circuit. Recovering the transmitted clock from the received signal is a first step in recovering the data. Only when the receive-side VCO (voltage-controlled oscillator) is phase-locked to the transmit-side VCO, the other DSP functions such as equalization and carrier recovery can commence. A typical receiver acquisition sequence will start with locking the receive VCO, followed by blind equalization (such as the constant modulus algorithm,...

This is a continuation from the previous tutorial - metal-coated fibers.   1. Transverse Modes in Optical Resonators Laser cavities differ in several significant ways from the closed microwave cavities that are commonly treated in electromagnetic theory tutorial. Optical resonators first of all usually have open sides, and hence always have diffraction losses because of energy leaking out the sides of the resonator to infinity. Optical resonators are also usually described in scalar or quasi plane-wave terms, with emphasis on the diffraction effects at apertures and mirror edges, rather than in vector terms with emphasis on matching boundary conditions. The...

This is a continuation from the previous tutorial - acousto-optic devices and applications.   1. Introduction An optical fiber has to be defended by some protective coating from mechanical damage during handling and from environmental factors during its use. In many cases, a polymer coating is appropriate for enough protection. However, there are a number of special applications of optical fibers in which ordinary polymer-coated fibers cannot be used. These applications can be divided into several groups: Increased reliability (hermeticity of the coating is important) High vacuum (when outgassing from the coating is undesirable) Possibility of soldering (embedded fibers, pigtails,...

This is a continuation from the previous tutorial - nonlinear compensation for digital coherent transmission.   1. Introduction When an acoustic wave propagates in an optically transparent medium, it produces a periodic modulation of the index of refraction via the elasto-optical effect. This provides a moving phase grating which may diffract portions of an incident light into one or more directions. This phenomenon, known as the acousto-optic (AO) diffraction, has led to a variety of optical devices that perform spatial, temporal, and spectral modulations of light. These devices have been used in optical systems for light-beam control and signal-processing applications....