Calculating Photodetector sensitivity

[Domail Singh]

Dear All

I need to calculate the photodetector sensitivity by using the parameters in PIN diode or APD component such as noise, dark current etc.
Can you guys please tell me how do i calculate the sensitivity?

Thanks
Regards

[Atul Sharma]

Hello Domail Singh. Greetings.

Why do you need to calculate the receiver sensitivity when you can set it in the global parameters itself. What for you need to calculate it?

With Regards
Atul Sharma

[Domail Singh]

Hello Atul Sharma

First of all thank you for the reply. I understand that we can set the sensitivity of the receiver in the global parameters. I am actually looking for the mathematical model to which i can compare the sensitivity. I hope you understand what i mean.
Regards

[nagesh kuknoor]

Hi Domail,
I think Atul is right. What for you need it. If you are looking for expression of receiver/photodiode sensitivity, you can google it and find it.

Thank you

[Domail Singh]

Hello Nagesh
I am designing a software defined network and i need to know the sensitivity mathematical model. I hope you got it.

Thanks

[Domail Singh]

Is the dark current, responsitivity etc all included in the receiver sensitivity ?

[Rajguru M. Mohan]

Hi Domail Singh,
Through Responsivity, we measures the input–output gain of a detector system. In the specific case of a photodetector, responsivity measures the electrical output per optical input.
It is the ratio of output current or voltage to the radiation energy.
The responsivity of a photodetector is usually expressed in units of either amperes or volts per watt of incident radiant power.

R = Eta* lambda (in micrometer)/1.24
eta is the quantum efficiency

The responsivity is generally defined for the steady state.

The term responsivity sensitivity are not same, the latter is the lowest detectable light level, which is typically determined by detection noise and significantly influenced by the required detection bandwidth.

A photodetector should ideally be operated in a spectral region where its responsivity is not far below the highest possible value.

Seeking your response.

Thanks and regards
Rajguru

[Domail Singh]

Hello Rajguru
Thank you for your efforts but the expression you have given represents responsitivity. I wan the mathematical model for sensitivity which is used in optisystem i mean some sort of idea regarding it. Hope you understand.

Thanks

[Kanwarjeet Singh]

Hello Rajguru,
You have provided an important information about the photodetector and as rightly pointed by other members the formula is for photo responsitivity not for sensitivity. Thanking you.

Regards
Kanwarjeet

[Ankita Sharma]

Hi Domail Singh,

What kind of mathematical model ? Can you please specify I don’t understand what you mean to ask ?

Regards
Ankita

[Domail Singh]

Hello Ankita
Thanks for your kind reply. I actually want the mathematical model for sensitivity which is used in optisystem. I hope you understand what i exactly need.
Regards

[nagesh kuknoor]

Hi all,

If Domail was looking for mathematical expression then i think Rajguru has just posted it for you. I hope your query is solved.

Thank you

[Domail Singh]

Hi Nagesh
It is the expression for responsitivity not sensitivity

[nagesh kuknoor]

Hello Domail,
Thank you for letting me know. I had confused it with Sensitivity. My mistake.

Regards

[shafeen al yasin]

Hello Domail

The formula for reciever sensitivity is given as:
Sensitivity=10×log10(kTB)+NF+C⁄N
You can refer to this link for more info
http://www.highfrequencyelectronics.com/index.php?option=com_content&view=article&id=553:receiver-sensitivity-and-equivalent-noise-bandwidth&catid=94:2014-06-june-articles&Itemid=189

I hope it will be useful.
Regards
Shafeen

[Domail Singh]

Hello Shafeen
Thank you for the expression. Are you sure the the sensitivity you chose in optisystem global parameters is given by the same formula?
Seeking your response.
Regards

[shafeen al yasin]

Hello Domail
I am not sure but i guess that must be the expression used because it is a general expression for receiver sensitivity. I hope it helps you.

Regards
Shafeen

[jyoti raina]

hi shafeen mam..
thanks for sharing the info..it will be very helpful indeed.

with regards
jyoti

[shafeen al yasin]

Hi jyoti
you are welcome. It is an immense pleasure to help.

Regards
Shafeen

[FAYIQA NAQSHBANDI]

HI DOMAIL..
I agree with Shafeen.. This is the correct formula for the Sensitivity. And i think optisystem uses the same.

Regards
FAYIQA

[Manoj Kumar]

Hi Shafeen,

I think you are correct about the formula for receiver sensitivity…
Thanks

Regards

[Domail Singh]

Hi Manoj
Are you sure it is the formula used in optisystem for derivation of sensitivity

[Domail Singh]

Hi Manoj
Are you sure it is the formula used in optisystem for derivation of sensitivity?

[shafeen al yasin]

Hi Manoj
Thank you for your appreciation. I hope it is helpful to Domail
Regards
Shafeen

[gaurav rajput]

Hi Shafeen,

Thanks for the link.. It is indeed very useful…

Regards

[Domail Singh]

Thanks Gaurav for the concern

[shafeen al yasin]

Hello Gaurav

You are welcome. I hope Domail finds it helpful.
Shafeen

[Rajguru M. Mohan]

Thank you shafeen al yasin,
For sharing such important information.
Are you sure this formula is valid for photodiode as you have use formula for sensitivity of a receiver by using following performance parameters: the noise figure (NF), the ENBW, and the carrier to noise ratio (C/N) required to achieve the desired quality signal.

I think this formula is used for photodetector as: The responsivity of a photodetector is usually expressed in units of either amperes or volts per watt of incident radiant power.

R = Eta* lambda (in micrometer)/1.24
eta is the quantum efficiency.

Seeking your response.

[Domail Singh]

HI Rajguru
As i mentioned above that this is expression for responsitivity. You are confusing responsitivtiy with sensitivity. The expression given by Shafeen is the actual expression for sensitivity but i am in doubt if it is used in optisystem to derive the value of sensitivity.
Hope you got my point.
Thanks

[jyoti raina]

hi rajguru sir..
i agree with domail sir..it is expression of responsitivity of photodiode..

with regards
jyoti

[shafeen al yasin]

Hello Rajguru,
You are welcome. You had mentioned the formula for responsitivity as mentioned by other members. You can look the receiver sensitivity formula. I hope it will be helpful to you too.

Regards
Shafeen

[Remo De Suza]

Hello Domail.

You have already the value for receiver sensitivity available in the global layout parameters. What is the purpose of recalculating it. You may check the dialog box for receiver sensitivity. I hope it is helpful.

Regards
Remo

[Domail Singh]

hi Remo
Thank you for the suggestion. I will look after it. This should help.

Regards
Domail

[Ankita Sharma]

Hi Domail,

Well I hope you got the desired information..

Regards
Ankita

[Domail Singh]

Hi Ankita
Thank you for the concern i appreciate.

Regards
Domail

[Manoj Kumar]

Hello Domail.

I agree with Domail that you have already have the value for receiver sensitivity available in the global layout parameters…. You may check the dialog box for receiver sensitivity. I hope it is helpful.

Regards

[Domail Singh]

Hello Manoj
firstly please correct the statement. You have written the wrong name. Anyway yes it is so i shall look into that

Regards
Domail

[deepak jha]

Hi all,

Thanks for the information..

Indeed a very nice discussion…

[Domail Singh]

Hello Deepak
You are welcome. I hope it is helpful and beneficial to all.

Regards
Domail

[Rajguru M. Mohan]

Hi Jyoti,
As we know a system’s sensitivity is the inverse of the stimulus level required to produce a threshold response, with the threshold typically chosen just above the noise level.
I think in case of photodetector, we only calculate responsivity not sensitivity.

As Responsivity measures the amount of output swing produced by a specified input swing while how “sensitive” a detector is, because you can always take an electrical signal and boost it with an low-noise amplifier. If you did this, your responsivity would go up, but the noise intrinsic to the detector would also be boosted (i.e., your signal-to-noise ratio would remain the same). There are multiple definitions for sensitivity; one common one is the noise-equivalent power, which is the amount of power required on the photodetector to produce a signal-to-noise ratio of 1.

So, it is confusion between them.

[Domail Singh]

Hi Rajguru
Thank you for the valuable information. It indeed is very very helpful. Thanks.

regards
Domail

[FAYIQA NAQSHBANDI]

HELLO RAJGURU..

Actually i would disagree here..I think sensitivity is more important in terms of simulation..I hope you would agree..

Regards

[syed fareed]

Hi Domail
Responsivity R of a photodiode is a measure of the sensitivity
to light, and it is defined as the ratio of the photocurrent IP to the
incident light power P at a given wavelength:
R = Ip/P

With Regards
Syed

[Domail Singh]

Hello Syed
I agree with you. Thank you for the info

Regards
Domail

[Manoj Kumar]

HI Domail,

I agree that in case of photodetector, we only calculate responsivity not sensitivity… The formula for calculating responsivity is mentioned by fareed.. Hope this helps

[Domail Singh]

Hi
Thank you Manoj for your suggestion i appreciate .

Regards
Domail

[Manoj Kumar]

Hi Domail,

You are welcome..

Thanks and regards

[shafeen al yasin]

Hi All,
It was an informative discussion. Thank you All.

Regards
Shafeen

[Rahul Tiwari]

Hi Shafeen,

Yes I agree it was an informative discussion..

Regards
Rahul Tiwari

[Kanwarjeet Singh]

Hi All,
This has been a good discussion indeed. Keep it up. This way one gets a booster i appreciate you all.

Regards
Kanwarjeet

[PHAM Van Dung]

The receiver sensitivity can be defined as the minimum average
optical power at given BER. There is a lot of parameters which contribute to the optical receiver sensitivity by following equation:
Optical sensitivity is given by:
Sen (dBm) = 10log[(OMA*(re+1))/((re-1)*2000)]
– re is the extinction ratio of the received optical signal
– OMA is the optical modulation amplitude:
OMA = Ipp/ρ (in μW)
– ρ is the photodetector responsivity (A/W)
Hope it can be useful for you

Ref: Accurately Estimating Optical Receiver Sensitivity – MAXIM intergrated

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