- This topic has 11 replies, 4 voices, and was last updated 9 years, 5 months ago by Alessandro Festa.
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July 24, 2015 at 5:40 am #22693Taiwo Ambali AbiolaParticipant
What is the exact length of the fiber that can be used to create a time delay of 50ns between two optical signal. I am currently implementing a system that requires splitting the pulse light into two, delay one by 50ns and later recombine the signal (a form of MZI). Actually, I am suppose to use a phase modulator on the delayed harm but it seems the effect of phase modulator can only come through with high frequency RF signal. But since my Photo detectors at the receiver can not support high frequency, I resulted into using fiber delay. What is the length of the fiber that could be used to get exact 50ns time delay.
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July 24, 2015 at 5:45 am #22694Taiwo Ambali AbiolaParticipant
How then can we convert the time delay into delay angle difference. I am actually trying to make the delay between the two signals to be (pie or 180 degree) difference. How do I go about the calculations.
Thanks so much and hope to hear from you soonest,.
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July 24, 2015 at 6:54 am #22701Abhishek ShramaParticipant
Hi Taiwo
Have you tried to delay signal with time component from library? Or you can can only want to delay signal with fiber? -
July 24, 2015 at 8:01 am #22702Taiwo Ambali AbiolaParticipant
Actually I am talking about laboratory experimental setup not optisystem. Thanks
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July 24, 2015 at 11:45 am #22703Alessandro FestaParticipant
Hi Taiwo, since the speed of the optical signals into fiber is v=c/n, where c is the speed of light into vacuum and n is the effective index of the fiber (1.5 about), to create a delay = T you need an amount of fiber equal to L = v * T.
In your case T = 50ns, so L = 10m. Depending on the precision you need on the 50ns, you need to know very well the n of the fiber. -
July 24, 2015 at 5:52 pm #22704Taiwo Ambali AbiolaParticipant
whaooo, this is quite helpful. Thanks so much Alessandro. I now got the delay to be 50ns as attached in the image.
Really appreciate this.
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July 27, 2015 at 1:58 am #22723Alessandro FestaParticipant
You are very welcome, it is my pleasure to helpforum members whenever I can!
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July 24, 2015 at 6:42 pm #22706Taiwo Ambali AbiolaParticipant
I also got the method to convert it to angle to be = (360*time delay)/Period
where Period = 1/F(frequency).So with that, my 50 ns delay is equivalent to 180degree (Pie) delay since I am running on 10MHz frequency which means the period= 100ns
Thanks a lot.
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July 25, 2015 at 12:43 am #22708Ashu vermaParticipant
Hello Taiwo
Alessandro almost explained the concept of delay.I just want to add that you should be familiar to the fiber parameters for exact calculation.One important oint i want to add is delay also depends upon your wavelength.For examples for a specific fiber (for which i have calculated) gives me results 49.16nm for 1310nm and 49.21ns for 1550.So if you are looking for exact delay then consider this point also.Thank you -
July 25, 2015 at 2:32 am #22713Taiwo Ambali AbiolaParticipant
I see! Thanks alot Samsung. Actually I am working with 1550 nm windows and the problem has been solved by Alessandro suggestion. I think the refractive index also comes to play there. Perhaps the refractive index of the fiber I used coincides with the one that could give 50ns though I didn’t check the refractive index.
Thanks so much for you suggestions.
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July 25, 2015 at 4:40 am #22716Ashu vermaParticipant
Welcome Taiwo
I just explained the effect of wavelength,because some times delay should be accurate.Otherwise Alessandro made a very good point and explained all. -
July 25, 2015 at 10:05 am #22717Taiwo Ambali AbiolaParticipant
Yes, I understand. Thanks so much
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