Lecture

Amplitude and Phase Modulation

Graph Chat

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.

Description

This lecture covers the basics of laser operation, including dispersion theory, gain and resonators, different types of lasers, noise characteristics, optical fibers, ultrafast lasers, and nonlinear frequency conversion. It also delves into amplitude modulation, explaining the theory, frequency doubling, and optical parametric amplification. The content progresses to phase modulation, discussing the principle of phase modulators, phase noise, and sideband picture. The lecture concludes with a detailed exploration of detectors, focusing on phototubes, photodiodes, and photomultiplier tubes, as well as the photoelectric effect and photoconductive detectors.

Official source

Ontological neighbourhood

Physics

Optics: Lasers

Related concepts (32)

Amplitude modulation

Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to that of the message signal, such as an audio signal. This technique contrasts with angle modulation, in which either the frequency of the carrier wave is varied, as in frequency modulation, or its phase, as in phase modulation.

Phase modulation

Phase modulation (PM) is a modulation pattern for conditioning communication signals for transmission. It encodes a message signal as variations in the instantaneous phase of a carrier wave. Phase modulation is one of the two principal forms of angle modulation, together with frequency modulation. In phase modulation, the instantaneous amplitude of the baseband signal modifies the phase of the carrier signal keeping its amplitude and frequency constant.

Modulation

In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a separate signal called the modulation signal that typically contains information to be transmitted. For example, the modulation signal might be an audio signal representing sound from a microphone, a video signal representing moving images from a video camera, or a digital signal representing a sequence of binary digits, a bitstream from a computer.

Quadrature amplitude modulation

Quadrature amplitude modulation (QAM) is the name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information. It conveys two analog message signals, or two digital bit streams, by changing (modulating) the amplitudes of two carrier waves, using the amplitude-shift keying (ASK) digital modulation scheme or amplitude modulation (AM) analog modulation scheme.

Frequency modulation

Frequency modulation (FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave. The technology is used in telecommunications, radio broadcasting, signal processing, and computing. In analog frequency modulation, such as radio broadcasting, of an audio signal representing voice or music, the instantaneous frequency deviation, i.e. the difference between the frequency of the carrier and its center frequency, has a functional relation to the modulating signal amplitude.

Related lectures (64)

Nonlinear Effects in Laser Systems

Explores nonlinear effects in laser systems, focusing on pulse generation and frequency modulation using gas and dye lasers.

Laser Systems and Atomic Transitions

Covers laser systems, atomic transitions, and light attenuation in lasers, focusing on the electron oscillator model and absorption coefficient.

Nonlinear Optics: Light-Matter Interaction

Explores nonlinear optics, covering light-matter interaction, second and third order effects, phase modulation, and frequency conversion processes.

Amplified Spontaneous Emission Noise in Fiber Amplifiers

Explores amplitude and phase modulation, noise figures, and detector noise in fiber amplifiers.

Laser as Light Source