Related Experiment Video
Updated: Jul 12, 2026
11:44
Real-Time DC-dynamic Biasing Method for Switching Time Improvement in Severely Underdamped Fringing-field Electrostatic MEMS Actuators
Published on: August 15, 2014
Spatiotemporal coherent control of lattice vibrational waves
T Feurer1, Joshua C Vaughan, Keith A Nelson
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Science (New York, N.Y.)
|January 18, 2003
Summary
Scientists achieved precise optical control over crystal lattice vibrations using shaped femtosecond laser pulses. This enabled the generation and manipulation of terahertz waves for advanced material studies.
Area of Science:
- Solid State Physics
- Optics
- Materials Science
Background:
- Controlling lattice dynamics in materials is crucial for understanding their properties.
- Previous methods lacked precise spatiotemporal control over lattice responses.
Purpose of the Study:
- To demonstrate automated optical control over coherent lattice responses.
- To generate and manipulate terahertz-frequency lattice vibrational waves.
Main Methods:
- Utilizing spatiotemporal femtosecond pulse shaping to create tailored excitation light fields.
- Directing light fields to specific regions within crystalline samples.
- Observing the resulting terahertz waves and their interference patterns.
Main Results:
- Achieved time- and position-dependent control over lattice responses across macroscopic scales.
- Generated terahertz waves emanating from multiple origins at lightlike speeds.
- Demonstrated control over wavefronts (tilted, focusing, amplified) through wave interference.
- Showcased terahertz traveling wave generation, amplification, and phased-array capabilities.
Conclusions:
- Spatiotemporal optical control offers a powerful new method for manipulating lattice dynamics.
- This technique enables the generation of complex terahertz wave phenomena.
- Potential applications in advanced materials characterization and terahertz technologies.
Related Concept Videos
01:24BIBO stability of continuous and discrete -time systems
System stability is a fundamental concept in signal processing, often assessed using convolution. For a system to be considered bounded-input bounded-output (BIBO) stable, any bounded input signal must produce a bounded output signal. A bounded input signal is one where the modulus does not exceed a certain constant at any point in time.
To determine the BIBO stability, the convolution integral is utilized when a bounded continuous-time input is applied to a Linear Time-Invariant (LTI) system.
To determine the BIBO stability, the convolution integral is utilized when a bounded continuous-time input is applied to a Linear Time-Invariant (LTI) system.
01:27State Space Representation
The frequency-domain technique, commonly used in analyzing and designing feedback control systems, is effective for linear, time-invariant systems. However, it falls short when dealing with nonlinear, time-varying, and multiple-input multiple-output systems. The time-domain or state-space approach addresses these limitations by utilizing state variables to construct simultaneous, first-order differential equations, known as state equations, for an nth-order system.
Consider an RLC circuit, a...
Consider an RLC circuit, a...
01:21State Space to Transfer Function
The conversion of state-space representation to a transfer function is a fundamental process in system analysis. It provides a method for transitioning from a time-domain description to a frequency-domain representation, which is crucial for simplifying the analysis and design of control systems.
The transformation process begins with the state-space representation, characterized by the state equation and the output equation. These equations are typically represented as:
The transformation process begins with the state-space representation, characterized by the state equation and the output equation. These equations are typically represented as:
01:27Time and frequency -Domain Interpretation of PI Control
Proportional-Integral (PI) controllers are essential in many control systems to improve stability and performance. They are commonly used in everyday devices like thermostats to enhance system damping and reduce steady-state error. When the zero in the controller's transfer function is optimally placed, the system benefits significantly in terms of stability and accuracy.
Acting as a low-pass filter, the PI controller slows the system's response and extends settling times. This requires careful...
Acting as a low-pass filter, the PI controller slows the system's response and extends settling times. This requires careful...
01:24Time and frequency -Domain Interpretation of Phase-lead Control
Phase-lead controllers are commonly used in various control systems to enhance response speed and stability. Adjusting the brightness on a television screen offers a practical example of phase-lead control. When contrast is enhanced, a phase-lead controller is employed. Mathematically, phase-lead control is identified when the first parameter is smaller than the second.
The design of phase-lead control involves the strategic placement of poles and zeros to balance steady-state error and system...
The design of phase-lead control involves the strategic placement of poles and zeros to balance steady-state error and system...
01:21Time and frequency -Domain Interpretation of Phase-lag Control
Phase-lag controllers are widely used in control systems to improve stability and reduce steady-state errors. A dimmer switch controlling the brightness of a light bulb serves as a practical example of phase-lag control, gradually adjusting the bulb's brightness. Mathematically, phase-lag control or low-pass filtering is represented when the factor 'a' is less than 1.
Phase-lag controllers do not place a pole at zero, but instead influence the steady-state error by amplifying any finite,...
Phase-lag controllers do not place a pole at zero, but instead influence the steady-state error by amplifying any finite,...