How do other types of optical spectrum analyzers work?

In summary, optical spectrum analyzers use an optical grating to separate out the wavelengths, and probably a linear high-speed CCD array to pick up the optical signals. There are a lot of websites out there selling OSAs, but their product descriptions are really vague, so it's been a bit difficult to get the info I wanted.
  • #1
Malibu
3
0
Okay, I'm writing about optical spectrum analysers as part of my AS coursework, but I've been having some problems finding more in depth information on how they work.

Can anyone explain to me how they work?
Or link me to a website that can tell me?

Thanks,
 
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  • #3
Thank's a lot!
That's just want I needed.

I'm not sure if there are other ways to make OSAs,
I've just stated that I was going to use one in my experiment plan (I don't actually have to DO the experiment, I just have to write a plan for it), but my tutor said I needed to give a bit more detail about how they work, and stuff.
There are a lot of websites out there selling OSAs, but their product descriptions are really vague, so it's been a bit difficult to get the info I wanted.

Thank's again! :)
 
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  • #5
Lol, I'm still thankful, because I'd been struggling, lol.

That link's of more use to me than the last, so I should be able to get my work finished in the next few minutes :)
 
  • #6
berkeman said:
Are there other ways to make optical spectrum analyzers?

I know two others. The fist one, even from the historical point of view, into use a prism, and the dispersive power of glass. There have been lots of different designs with prisms.
But the resolving power is low. That is, it is hard to separate very near wavelengths.
Grating spectroscopes have a far bigger resolution.
But the biggest resolution is obtained with FFT spectrometers. FFT stands for Fast Fourier Transform. It is done using a double Michelson and Morley interferometer with a mobile arm. One stage is used for a very precise distance measurement with a known wavelength and the other for the unknown one. The intensity of interferences is measured in function of the arms length and then, with a computer, the Fourier transform is computed. This transform is the spectrum of the unknown light. The precision of this kind on interferometer is equal to the precision of the length measure. If you made the measure for a variation of 1 meter of arm length with a precision of 1000 nm, you will obtain a resolution of 10^-6

By the way, you can make a primitive grating spectroscope, using a CD as grating.
 

1. What is an Optical Spectrum Analyser?

An Optical Spectrum Analyser (OSA) is a scientific instrument used to measure and analyze the spectral content of light. It can detect and measure the intensity of different wavelengths of light present in a beam of light.

2. How does an Optical Spectrum Analyser work?

An OSA works by splitting a beam of light into different wavelengths using a diffraction grating or a prism. The separated wavelengths are then directed onto a photodetector, which measures the intensity of each wavelength. The resulting data is then displayed on a graph, showing the intensity of each wavelength present in the light.

3. What are the applications of Optical Spectrum Analysers?

OSAs are commonly used in various fields such as telecommunications, spectroscopy, and optical fiber technology. They are also used in research and development for analyzing and testing the spectral characteristics of new materials and devices.

4. How is an Optical Spectrum Analyser different from a Spectrophotometer?

While both instruments measure the spectral content of light, they differ in their range and resolution. OSAs have a wider range and higher resolution, making them more suitable for analyzing complex spectra with multiple peaks. Spectrophotometers, on the other hand, have a narrower range and lower resolution, which makes them more suitable for measuring specific wavelengths with high precision.

5. What factors should be considered when choosing an Optical Spectrum Analyser?

The main factors to consider when choosing an OSA are its wavelength range, resolution, and sensitivity. Other important factors include the type of detector used, measurement speed, and the availability of additional features such as polarization measurement or built-in light sources. The intended application and budget should also be taken into account when selecting an OSA.

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