Optical wavelength test measurement equipment - wavelength meter
The basic principle of a wavelength meter is to utilise the resonant properties of a resonant cavity to achieve wavelength measurements. A resonant cavity is a space with specific geometry and dimensions, which can generate a stable electromagnetic field within a certain frequency range. When the external electromagnetic wave enters the resonant cavity, if its frequency is equal to or close to the intrinsic frequency of the resonant cavity, it will form a strong resonance phenomenon inside the cavity, so that the electromagnetic field strength inside the cavity reaches the maximum. On the contrary, if the frequency of the external electromagnetic wave differs greatly from the intrinsic frequency of the resonant cavity, a weak or no resonance phenomenon will be formed in the cavity, so that the intensity of the electromagnetic field in the cavity is very small or zero. Therefore, by adjusting the size or shape of the resonant cavity so that its intrinsic frequency matches the frequency of the signal to be measured, the wavelength of the signal to be measured can be measured.
Wavelength meters can be divided into two types according to their coupling method: pass-through and absorption. Through the type wavelength meter through the two coupling structure (input and output) connected in series in the measurement system. Measurement, as long as the adjustment of the wavelength meter tuning rod or piston, so that the resonant frequency of the resonant cavity is equal to the frequency of the signal to be measured, at this time the cavity to produce resonance, so that the strongest electromagnetic field in the cavity, so that through the output coupling structure coupling the output of the power is maximum, and thus through the oscilloscope output of the detector current (amplitude) is also the largest. When adjusting the wavelength meter tuning rod or piston to make the cavity detuned, the electromagnetic field in the cavity is very weak, and thus the detector current is correspondingly small or even zero. Absorption wavelength meter cavity only a coupling structure. When adjusting the wavelength meter tuning piston so that the resonant frequency of the cavity is equal to the frequency of the signal to be measured, the cavity resonates, at this time, part of the energy in the system into the cavity, so that the detector output of the detector current is reduced to a minimum. When the cavity is detuned, the electromagnetic field in the cavity is very weak, almost no absorption of energy in the system, the indicator has a normal output.
The advantages of wavelength meter are mainly as follows:
- Measurement speed is fast, generally only a few seconds to complete the wavelength measurement.
- High measurement accuracy, generally can reach 0.01% or higher.
- Wide measurement range, generally can cover the frequency band from microwave to visible light.
- Simple measurement method, only need to adjust the parameters of the resonant cavity, without complex calibration and calculation.
The main disadvantages of wavelength meters are as follows:
- Measurement sensitivity is limited by the Q value of the resonant cavity, the higher the Q value, the higher the sensitivity, but also increases the loss and temperature sensitivity of the resonant cavity.
- Measurement stability is affected by environmental factors, temperature, humidity, air pressure and other factors will lead to changes in the size and shape of the resonant cavity, thus affecting the wavelength measurement results.
- Measurement resolution is limited by the bandwidth of the resonant cavity, the narrower the bandwidth, the higher the resolution, but also reduces the dynamic range and signal-to-noise ratio of the wavelength meter.
The main application areas of wavelength meters are as follows:
- Optical communication: wavelength meters can be used to measure the wavelength of optical signals in optical fibre communication, as well as the wavelength characteristics of optical devices, such as lasers, optical amplifiers, optical filters and so on.
- Photonics: Wavelength meters can be used to measure the wavelength of optical signals in photonics technology, as well as the wavelength characteristics of photonic devices, such as optical switches, optical modulators, optical sensors and so on.
- Spectroscopy: Wavelength meters can be used to measure the wavelength of optical signals in spectroscopy, as well as the spectral properties, such as absorption spectra, emission spectra, fluorescence spectra, and so on.
- Optical Measurement: Wavelength meters can be used to measure the wavelength of optical signals in optical measurement, as well as optical parameters such as refractive index, dispersion, phase, etc.
The basic principle of a wavelength meter is to utilise the resonant properties of a resonant cavity to achieve wavelength measurements. A resonant cavity is a space with specific geometry and dimensions, which can generate a stable electromagnetic field within a certain frequency range. When the external electromagnetic wave enters the resonant cavity, if its frequency is equal to or close to the intrinsic frequency of the resonant cavity, it will form a strong resonance phenomenon inside the cavity, so that the electromagnetic field strength inside the cavity reaches the maximum. On the contrary, if the frequency of the external electromagnetic wave differs greatly from the intrinsic frequency of the resonant cavity, a weak or no resonance phenomenon will be formed in the cavity, so that the intensity of the electromagnetic field in the cavity is very small or zero. Therefore, by adjusting the size or shape of the resonant cavity so that its intrinsic frequency matches the frequency of the signal to be measured, the wavelength of the signal to be measured can be measured.
Wavelength meters can be divided into two types according to their coupling method: pass-through and absorption. Through the type wavelength meter through the two coupling structure (input and output) connected in series in the measurement system. Measurement, as long as the adjustment of the wavelength meter tuning rod or piston, so that the resonant frequency of the resonant cavity is equal to the frequency of the signal to be measured, at this time the cavity to produce resonance, so that the strongest electromagnetic field in the cavity, so that through the output coupling structure coupling the output of the power is maximum, and thus through the oscilloscope output of the detector current (amplitude) is also the largest. When adjusting the wavelength meter tuning rod or piston to make the cavity detuned, the electromagnetic field in the cavity is very weak, and thus the detector current is correspondingly small or even zero. Absorption wavelength meter cavity only a coupling structure. When adjusting the wavelength meter tuning piston so that the resonant frequency of the cavity is equal to the frequency of the signal to be measured, the cavity resonates, at this time, part of the energy in the system into the cavity, so that the detector output of the detector current is reduced to a minimum. When the cavity is detuned, the electromagnetic field in the cavity is very weak, almost no absorption of energy in the system, the indicator has a normal output.
The advantages of wavelength meter are mainly as follows:
- Measurement speed is fast, generally only a few seconds to complete the wavelength measurement.
- High measurement accuracy, generally can reach 0.01% or higher.
- Wide measurement range, generally can cover the frequency band from microwave to visible light.
- Simple measurement method, only need to adjust the parameters of the resonant cavity, without complex calibration and calculation.
The main disadvantages of wavelength meters are as follows:
- Measurement sensitivity is limited by the Q value of the resonant cavity, the higher the Q value, the higher the sensitivity, but also increases the loss and temperature sensitivity of the resonant cavity.
- Measurement stability is affected by environmental factors, temperature, humidity, air pressure and other factors will lead to changes in the size and shape of the resonant cavity, thus affecting the wavelength measurement results.
- Measurement resolution is limited by the bandwidth of the resonant cavity, the narrower the bandwidth, the higher the resolution, but also reduces the dynamic range and signal-to-noise ratio of the wavelength meter.
The main application areas of wavelength meters are as follows:
- Optical communication: wavelength meters can be used to measure the wavelength of optical signals in optical fibre communication, as well as the wavelength characteristics of optical devices, such as lasers, optical amplifiers, optical filters and so on.
- Photonics: Wavelength meters can be used to measure the wavelength of optical signals in photonics technology, as well as the wavelength characteristics of photonic devices, such as optical switches, optical modulators, optical sensors and so on.
- Spectroscopy: Wavelength meters can be used to measure the wavelength of optical signals in spectroscopy, as well as the spectral properties, such as absorption spectra, emission spectra, fluorescence spectra, and so on.
- Optical Measurement: Wavelength meters can be used to measure the wavelength of optical signals in optical measurement, as well as optical parameters such as refractive index, dispersion, phase, etc.