Effect of light feedback (OF)
Laser has been observed from the early stages of laser development.
Although OF will result in unpredictable and unpredictable operations in the laser system, it will also cause measurable disturbances to the operating parameters, which can be used for metering purposes.
In this work, we use this "self"
Mixing effect to infer the emission spectrum of a semiconductor laser using a laser
Feedback interferometer where coherent sampling of the reinjected field is performed using the end voltage of the laser.
We prove that the method uses a single-frequency quantum cascade laserand multiple-
Longitudinal mode states and can solve the spectral features that cannot be reliably distinguished by traditional Fourier transform spectra.
We also quantitatively studied the frequency perturbation of the single laser mode and found that it is very consistent with the prediction OF the excess phase equation at the center of the laser theory.
Light feedback (OF)
When the radiation emitted from the laser is reflected by the external target and partially re-injected into the laser cavity.
The influence of has been observed since the early development of the laser, and it is well known that it will cause adverse phenomena in the laser, including increased intensity noise, coherent collapse, chaotic behavior and transition between laser working states.
Nevertheless, optics (homodyne)
A mixture of re-injected radiation and interior
The cavity photon field can also cause predictable and measurable disturbances of laser operating parameters that depend on the phase and amplitude of the reinjection field.
In the case of semiconductor lasers, the laser response to the pair can be induced by the laser terminal voltage, thus encapsulating information about the external cavity and the optical properties of the target.
This leads to the concept of laser.
Feedback interference (LFI)
Mixing effect where a single laser device acts as source, local vibration, mixer, and bulk noise-
The limited detector thus forms a compact interference sensor.
The experimental simplicity of these protocols prompts them to be used in a range of sensing applications, including coherent imaging and microscopy, distance-
Measurement range, vibration measurement and displacement sensing, material analysis and Doppler flow measurement.
In addition, the applicability of LFI has been demonstrated in a wide range of classesA and class-
B. Laser systems from visible to microwave regions, including gas lasers
Vertical plane semiconductor diode laser
Cavity Surface Emitting Laser (VCSELs), mid-
Infrared and Hertz (THz)-
Frequency quantum cascade laser (QCLs)
, Inter-band cascade laser, fiber and fiber ring laser and solid-state lasers.
This remarkable universality of the self
The mixing phenomenon and its intrinsic dependence on laser electronics and optical properties also make it possible to measure basic laser parameters, including line width enhancement factors (LEF)
And laser line width.
In this work, we show a new mode of LFI in which, in response to the expansion of the external cavity, changes in the end voltage of the Hertz QCL are used to infer isolated lasers, for two singleand multiple-
Portrait mode running status.
Although our scheme is suitable for all types of semiconductor lasers, it provides a simple Fourier transform infrared (FTIR)
Spectral methods commonly used for mid spectral representationand far-
Infrared laser and avoid dependence on slow, insensitive or low temperature
Cooled Hertz detector
The core of our approach is the ability to recover interference voltage signals with high signals. to-
Noise ratio in weak of state;
In this case, the spectral properties of isolated laser are superior to those of external cavity, and the phenomenon of line splitting and mode hopping is suppressed.
The zero-beat nature of the LFI scheme makes this possible, which inherently provides a very high sensitivity, potentially at the limits of quantum noise.
As far as we know, we also measured for the first time the frequency change in the laser mode of placing an order in.
We confirm the observation of small perturbation of isolated laser emission frequency and find very consistent with the prediction of excess phase equation at the center of laser theory under.