Related Experiment Video
Updated: Jul 8, 2025
15:58
Measurement of Coherence Decay in GaMnAs Using Femtosecond Four-wave Mixing
Published on: December 3, 2013
5.8K
Frequency noise measurements using coherent self-heterodyne detection
Optics Letters
|December 15, 2023
Summary
We present a new method for measuring laser frequency noise (FN) spectrum by adjusting the delay in a self-heterodyne setup. This technique offers a cost-effective and simpler alternative for determining laser linewidth.
Area of Science:
- Optics and Photonics
- Laser Physics
- Metrology
Background:
- Accurate characterization of laser frequency noise (FN) is crucial for various applications.
- Conventional methods for measuring FN spectrum and laser linewidth can be complex and costly.
Purpose of the Study:
- To develop a refined and cost-effective method for extracting the frequency noise spectrum of lasers.
- To provide a simpler alternative to existing state-of-the-art techniques for FN measurements.
Main Methods:
- Tailoring the delay in a conventional delayed self-heterodyne setup to sub-coherence lengths.
- Utilizing electrical spectrum analyzer traces for direct proportionality to the FN spectrum.
- Validating the proposed method against a commercial frequency noise analyzer.
Main Results:
- Achieved direct proportionality between electrical spectrum analyzer traces and the frequency noise spectrum.
- Successfully determined the intrinsic linewidth of the lasers.
- Demonstrated comparable results to a commercial frequency noise analyzer.
Conclusions:
- The proposed method offers a cost-effective and simplified approach for measuring laser frequency noise spectrum.
- Minimal post-processing is required compared to current state-of-the-art techniques.
- This technique provides a valuable tool for laser characterization.
Related Concept Videos
01:08Determination of Expected Frequency
2.2K
Suppose one wants to test independence between the two variables of a contingency table. The values in the table constitute the observed frequencies of the dataset. But how does one determine the expected frequency of the dataset? One of the important assumptions is that the two variables are independent, which means the variables do not influence each other. For independent variables, the statistical probability of any event involving both variables is calculated by multiplying the individual...
2.2K
01:08IR Spectrum Peak Splitting: Symmetric vs Asymmetric Vibrations
1.0K
Identical bonds within a polyatomic group can stretch symmetrically (in-phase) or asymmetrically (out-of-phase). Similar to hydrogen bonding, these vibrations also influence the shape of the IR peak. Generally, asymmetric stretching frequencies are higher than symmetric stretching frequencies. For example, primary amines exhibit two distinct IR peaks between 3300–3500 cm−1 corresponding to the symmetric and asymmetric N-H stretching, while secondary amines exhibit a single...
1.0K
01:17NMR Spectrometers: Radiofrequency Pulses and Pulse Sequences
809
A pulse is a short burst of radio waves distributed over a range of frequencies that simultaneously excites all the nuclei in the sample. Upon passing a radio frequency pulse along the x-axis, the nuclei absorb energy corresponding to their Larmor frequencies and achieve resonance. This shifts the net magnetization vector from the z-axis toward the transverse plane. This angle of rotation of the magnetization vector, or the flip angle, is proportional to the duration and intensity of the pulse.
809
01:30Electronic Distance Measuring Instruments
37
Electronic Distance Measuring Instruments (EDMs) are essential tools in modern surveying, offering precise distance measurements by emitting electromagnetic signals and calculating the time required for these signals to travel to a target and return. Two primary types of signals are used in EDMs — light waves and microwaves — each suited to specific environmental and distance requirements. Light-wave-based EDMs utilize either infrared or laser light, providing high accuracy over short...
37
01:11Sampling Continuous Time Signal
251
In signal processing, a continuous-time signal can be sampled using an impulse-train sampling technique, followed by the zero-order hold method. Impulse-train sampling involves the use of a periodic impulse train, which consists of a series of delta functions spaced at regular intervals determined by the sampling period. When a continuous-time signal is multiplied by this impulse train, it generates impulses with amplitudes corresponding to the signal's values at the sampling points.
In the...
In the...
251
01:11Atomic Nuclei: Larmor Precession Frequency
1.4K
The earth's gravitational field produces a 'twisting force' perpendicular to the angular momentum of a spinning mass (such as a spinning top) that causes the mass to 'wobble' around the gravitational field axis in a phenomenon called precession. Similarly, the magnetic moment (μ) of a spinning nucleus precesses due to an external magnetic field directed along the z-axis. The precession of the magnetic moment vector about the magnetic field is called Larmor precession,...
1.4K