Home Forums SYSTEM saturation energy of soa

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    • #20321

      Hello everybody
      after going through tutorials related to gain saturation in semiconductor optical amplifier, I am unable to figure out how saturation energy in soa is calculated. In the tutorial it is mentioned that from the parameters of SOA saturation energy comes out to be 3.7PJ. .I would like to know the formulla for calculation of saturation energy in SOA.The tutoril link is

      SOA Gain Saturation – Gaussian Pulses

      Kindly copy paste above link in yr browser.saturation energy 3.7PJ is mentioned in first page of tutorial.
      I have checked in component help of soa and no saturation energy formulla is given. So if anybody can help me how saturation energy is calculated from soa parameters.

    • #20329
      Dr Rk Sethi

      Vipul Hi,
      After going through tutorials you are unable to figure out, how saturation energy in SOA is calculated. In the quoted tutorial the parameters of SOA saturation energy comes out to be 3.7PJ. The formula for calculation of saturation energy in SOA is:
      Esat = hv σm / σd

      σd the gain cross section, the differential gain
      h is planck’s constant
      σm = w d / Γ the cross-section area of the wave-guide mode
      Γ – the confinement factor
      w – width of SOA
      d – thickness
      You need to refer some standard text book on SEMICONDUCTOR OPTICAL AMPLIFIER to understand it completely.

    • #20564

      Hi Vipul,

      First, I would recommend you to read the detailed answer of Rk Sethi (which is basically answers your question). From myself I would just like to add that in most of design cases in practice we are dealing with the saturation input power which is the output optical power at which the amplifier gain decreases by a factor of two (or by 3 dB). For your further understanding, I am attaching you a short overview about SOA from Cornell University, which is in a free access online.

    • #20649
      Ashu verma

      Hi Ravil and RK sethi,in optisystem SOA model there is input facet reflectivity and output facet reflectivity is 0.Is it possible in practical SOA,s? As as far as reflectivity of SOA is concerned it may be reduced to min but can not be zero.Correct me if i am wrong somewhere.

      • #20744
        Damian Marek

        Hi Sam sung,

        Generally there is no explicit limit we place on parameters to keep the simulations realistic. The user is free to choose any value they would like, on the other hand some parameters are limited by the simulation model. As a simple example, the loss of a device may be limited to a positive number.

        I would have to agree that a 0 reflectivity is not exactly realistic. BUT, after a very quick search I found this article:


        which says they achieved an output reflectivity of -59.5dB. In linear form this is 0.000001.


    • #20652

      Hi Sam Sung,

      I agree with your point of view and don’t think that it is practically possible to make the reflectivity to be equal exactly zero. However, it is known that it can be reduced to some negligible value (is this what that “0” mean?). Dear Optiwave Team, please, let us know under what conditions such reflectivity is possible…

    • #20655
      Ashu verma

      Thank you Ravil,I have read many articles that faet reflectivity can be reduced by tilted active region or by doing anti reflective coatings. But achieving 0 value is ,i think no practical.may be Damian give this answer better.

    • #20760

      You are welcome, Sam Sung! The exact “0” is not achievable due to known physical reasons. However, please, take a look at Damian’s comment. He has highlighted a very interesting point. Thank you for your answer, Damian!

    • #20766
      Abhishek Shrama

      Thankyou for clearing my doubt too!!
      I am also using SOA with 0 facet reflectivity in my system setup for all optical t and d flip flop. and have been asked same question.
      I also took is as a reference from an article

    • #20775
      Ashu verma

      Thank you Damian for explaining this concept of SOA facet reflectivity.As i am working on the SOA non linearity and applications.Most important point is ,the paper you have given is clearly shows that tn can be possible to achieve value close to zero.So this will work as strong point me to prove,who soever may ask me question about this.
      Also tank you Ravil as you also supported my query,you are very helpful too 🙂

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