Pehea e hōʻemi ai i ka walaʻau o nā photodetectors

Pehea e hōʻemi ai i ka walaʻau o nā photodetectors

ʻO ka walaʻau o nā photodetectors e komo pū ana me: ka walaʻau o kēia manawa, ka walaʻau wela, ka walaʻau pana, ka walaʻau 1/f a me ka walaʻau wideband, a pēlā aku. He ʻano paʻakikī wale nō kēia hoʻokaʻawale ʻana. I kēia manawa, e hoʻolauna mākou i nā ʻano walaʻau kikoʻī a me nā hoʻokaʻawale ʻana e kōkua i nā mea a pau e hoʻomaopopo maikaʻi i ka hopena o nā ʻano walaʻau like ʻole ma nā hōʻailona puka o nā photodetectors. Ma ka hoʻomaopopo wale ʻana i nā kumu o ka walaʻau hiki iā mākou ke hōʻemi maikaʻi a hoʻomaikaʻi i ka walaʻau o nā photodetectors, a laila e hoʻomaikaʻi i ka lakio hōʻailona-i-walaʻau o ka ʻōnaehana.

ʻO ka walaʻau pana he loli maʻamau i hoʻokumu ʻia e ke ʻano discrete o nā mea lawe ukana. ʻOi loa i ka hopena photoelectric, i ka wā e paʻi ai nā photons i nā ʻāpana photosensitive e hana i nā electrons, ʻo ka hanauna o kēia mau electrons he random a kūlike me ka hoʻolaha Poisson. ʻO nā ʻano spectral o ka walaʻau pana he pālahalaha a kūʻokoʻa i ka nui o ke alapine, a no laila ua kapa ʻia hoʻi he walaʻau keʻokeʻo. Wehewehe makemakika: Hiki ke hōʻike ʻia ka waiwai kumu awelika square (RMS) o ka walaʻau pana penei:

Ma waena o lākou:

e: Hoʻouka uila (ma kahi o 1.6 × 10-19 coulombs)

ʻIdark: Au pōʻeleʻele

Δf: Pākuʻi leo

Kūlike ka walaʻau pana me ka nui o ke au a paʻa i nā alapine (frequencies) āpau. Ma ke ʻano hana, hōʻike ʻo Idark i ke au pouli o ka photodiode. ʻO ia hoʻi, i ka nele o ka mālamalama, loaʻa i ka photodiode ka walaʻau au pouli i makemake ʻole ʻia. Ma ke ʻano he walaʻau kūlohelohe ma ka ʻaoʻao mua loa o ka photodetector, ʻo ka nui o ke au pouli, ʻo ka nui o ka walaʻau o ka photodetector. Hoʻopilikia pū ʻia ke au pouli e ka volta hana bias o ka photodiode, ʻo ia hoʻi, ʻo ka nui o ka volta hana bias, ʻo ka nui o ke au pouli. Eia naʻe, hoʻopilikia pū ka volta hana bias i ka capacitance junction o ka photodetector, a laila e hoʻopilikia ana i ka wikiwiki a me ka bandwidth o ka photodetector. Eia kekahi, ʻo ka nui o ka volta bias, ʻo ka nui o ka wikiwiki a me ka bandwidth. No laila, ma ke ʻano o ka walaʻau pana, ke au pouli a me ka hana bandwidth o nā photodiodes, pono e hoʻokō ʻia ka hoʻolālā kūpono e like me nā koi o ka papahana maoli.

2. 1/f Walaʻau ʻĀlohilohi

ʻO ka walaʻau 1/f, i ʻike ʻia hoʻi he walaʻau flicker, ʻike nui ʻia ma ka pae alapine haʻahaʻa a pili ia i nā mea e like me nā hemahema o nā mea a i ʻole ka maʻemaʻe o ka ʻili. Mai kāna kiʻikuhi hiʻohiʻona spectral, hiki ke ʻike ʻia he ʻoi aku ka liʻiliʻi o kona nui spectral mana ma ka pae alapine kiʻekiʻe ma mua o ka pae alapine haʻahaʻa, a no kēlā me kēia 100 manawa e piʻi ai ke alapine, e emi ana ka walaʻau spectral density ma ka 10 manawa. ʻO ka nui spectral mana o ka walaʻau 1/f he inversely proportional i ke alapine, ʻo ia hoʻi:

Ma waena o lākou:

SI(f): Ka nui o ka mana walaʻau

ʻO wau: I kēia manawa

f: Alapine (frequency)

He mea nui ka walaʻau 1/f ma ka pae alapine haʻahaʻa a nāwaliwali i ka piʻi ʻana o ke alapine. ʻO kēia ʻano e lilo ia i kumu nui o ka hoʻopilikia ʻana i nā noi alapine haʻahaʻa. ʻO ka walaʻau 1/f a me ka walaʻau wideband e hele mai ana mai ka walaʻau voltage o ka amplifier hana i loko o ka photodetector. Nui nā kumu walaʻau ʻē aʻe e hoʻopilikia i ka walaʻau o nā photodetectors, e like me ka walaʻau mana o nā amplifier hana, ka walaʻau o kēia manawa, a me ka walaʻau thermal o ka pūnaewele kū'ē i ka loaʻa o nā kaapuni amplifier hana.

3. Ka walaʻau uila a me ke au o ka mea hoʻonui hana: Ua hōʻike ʻia nā densities spectral voltage a me ke au ma ke kiʻi aʻe:

I loko o nā kaapuni hoʻonui hana, ua māhele ʻia ka walaʻau o ke au i ka walaʻau o ke au i loko o ka pae a me ka walaʻau o ke au hoʻohuli. Ke kahe nei ka walaʻau o ke au i loko o ka pae i+ ma o ke kū'ē kūloko kumu Rs, e hana ana i kahi walaʻau voltage like u1= i+*Rs. Ke kahe nei ka walaʻau o ke au hoʻohuli I- ma o ke kū'ē kūlike loaʻa R e hana i ka walaʻau voltage like u2= I-* R. No laila, i ka wā e nui ai ka RS o ka lako mana, nui loa hoʻi ka walaʻau voltage i hoʻololi ʻia mai ka walaʻau o ke au. No laila, no ka hoʻomaikaʻi ʻana no ka walaʻau maikaʻi aʻe, ʻo ka walaʻau o ka lako mana (me ke kū'ē kūloko) he kuhikuhi koʻikoʻi hoʻi no ka hoʻomaikaʻi ʻana. ʻAʻole loli ka nui o ka spectral o ka walaʻau o ke au me nā loli alapine. No laila, ma hope o ka hoʻonui ʻia ʻana e ke kaapuni, ʻo ia, e like me ke au pouli o ka photodiode, e hana piha i ka walaʻau pana o ka photodetector.

4. Hiki ke helu ʻia ka walaʻau wela o ka pūnaewele kū'ē no ka loaʻa (amplification factor) o ke kaapuni amplifier hana me ka hoʻohana ʻana i kēia ʻano hana:

Ma waena o lākou:

k: Paʻa Boltzmann (1.38 × 10-23J/K)

T: Mahana Loa (K)

R: Pili ka walaʻau wela o ke kū'ē (ohms) i ka mahana a me ka waiwai kū'ē, a he pālahalaha kona spectrum. Hiki ke ʻike ʻia mai ke ʻano hana ʻo ka nui o ka waiwai kū'ē loaʻa, ʻo ka nui o ka walaʻau wela. ʻO ka nui o ka bandwidth, ʻo ka nui nō hoʻi o ka walaʻau wela. No laila, i mea e hōʻoia ai e hoʻokō ka waiwai kū'ē a me ka waiwai bandwidth i nā koi loaʻa a me nā koi bandwidth, a i ka hopena e koi pū i ka walaʻau haʻahaʻa a i ʻole ka lakio signal-to-noise kiʻekiʻe, pono e noʻonoʻo pono ʻia a loiloi ʻia ke koho ʻana o nā resistors loaʻa ma muli o nā koi papahana maoli e hoʻokō ai i ka lakio signal-to-noise kūpono o ka ʻōnaehana.

Hōʻuluʻulu manaʻo

He kuleana koʻikoʻi ko ka ʻenehana hoʻomaikaʻi walaʻau i ka hoʻomaikaʻi ʻana i ka hana o nā photodetectors a me nā mea uila. ʻO ke kiko kiʻekiʻe ke ʻano o ka walaʻau haʻahaʻa. Ke koi nei ka ʻenehana i ka pololei kiʻekiʻe, ke piʻi aʻe nei nā koi no ka walaʻau, ka lakio signal-to-noise, a me ka mana walaʻau like o nā photodetectors.