Silicon optical modulator ya FMCW

Silicon kuwala modulatorya FMCW

Monga tonse tikudziwa, chimodzi mwazinthu zofunika kwambiri mu machitidwe a Lidar ochokera ku FMCW ndi modulator yolunjika kwambiri. Mfundo yake yogwirira ntchito ikuwonetsedwa pachithunzi chotsatirachi: Kugwiritsa ntchitoModulator ya DP-IQzochokerakusintha kwa mbali imodzi (SSB), chapamwamba ndi chapansiMZMKugwira ntchito pa null point, pamsewu ndi pansi pa gulu la mbali la wc+wm ndi WC-WM, wm ndiye ma modulation frequency, koma nthawi yomweyo njira yotsika imayambitsa kusiyana kwa gawo la madigiri 90, ndipo pamapeto pake kuwala kwa WC-WM kumazimitsidwa, nthawi yosinthira pafupipafupi ya wc+wm imachotsedwa. Mu Chithunzi b, LR blue ndiye chizindikiro cha FM chirp chapafupi, RX orange ndiye chizindikiro chowonetsedwa, ndipo chifukwa cha Doppler effect, chizindikiro chomaliza cha beat chimapanga f1 ndi f2.

Mtunda ndi liwiro lake ndi izi:

Nkhani yotsatirayi ndi yofalitsidwa ndi Shanghai Jiaotong University mu 2021, yokhudzaSSBmajenereta omwe amagwiritsa ntchito FMCW kutengerama modulators a kuwala kwa silicon.

Kagwiridwe ka ntchito ka MZM kakuonetsedwa motere: Kusiyana kwa magwiridwe antchito a ma modulators apamwamba ndi otsika a mkono ndi kwakukulu. Chiŵerengero cha kukana kwa carrier sideband ndi chosiyana ndi kuchuluka kwa ma frequency modulation, ndipo zotsatira zake zimakhala zoyipa kwambiri pamene ma frequency akuwonjezeka.

Mu chithunzi chotsatirachi, zotsatira za mayeso a dongosolo la Lidar zikusonyeza kuti a/b ndiye chizindikiro cha beat pa liwiro lomwelo komanso mtunda wosiyana, ndipo c/d ndiye chizindikiro cha beat pa mtunda womwewo komanso pa liwiro losiyana. Zotsatira za mayeso zinafika pa 15mm ndi 0.775m / s.

Apa, kugwiritsa ntchito silicon kokhamodulator yowalaza FMCW zikukambidwa. Zoona zake n'zakuti, zotsatira za silicon optical modulator si zabwino ngati zaLiNO3 modulator, makamaka chifukwa mu silicon optical modulator, phase change/absorption coefficient/junction capacitance siili yolunjika ndi kusintha kwa voltage, monga momwe chithunzi chili pansipa chikusonyezera:

Ndiko kuti,

Ubale wa mphamvu yotulutsa yamodulatordongosolo lili motere
Zotsatira zake ndi kuchotsedwa kwa dongosolo lapamwamba:

Izi zipangitsa kuti chizindikiro cha ma beat frequency chiwonjezeke komanso kuti chiŵerengero cha ma signal-to-noise chichepe. Ndiye njira yowonjezerera linearity ya silicon light modulator ndi iti? Pano tikungokambirana za makhalidwe a chipangizocho chokha, ndipo sitikambirana za njira yolipirira pogwiritsa ntchito zida zina zothandizira.
Chimodzi mwa zifukwa zomwe zimapangitsa kuti gawo la modulation lisakhale lolunjika ndi voltage ndikuti gawo la kuwala mu waveguide lili ndi magawo osiyanasiyana a magawo olemera ndi owala ndipo kuchuluka kwa kusintha kwa gawo kumakhala kosiyana ndi kusintha kwa voltage. Monga momwe chithunzichi chikusonyezera. Dera lochepa lomwe lili ndi kusokonezeka kwakukulu limasintha pang'ono kuposa lomwe lili ndi kusokonezeka kwa kuwala.

Chithunzi chotsatirachi chikuwonetsa ma curve osinthika a TID ya third-order intermodulation ndi harmonic distortion ya second-order SHD yokhala ndi kuchuluka kwa clutter, ndiko kuti, modulation frequency. Zitha kuwoneka kuti mphamvu yoletsa ya detuning ya heavy clutter ndi yayikulu kuposa ya clutter yopepuka. Chifukwa chake, remixing imathandiza kukonza linearity.

Zomwe zili pamwambapa zikufanana ndi kuganizira C mu RC model ya MZM, ndipo mphamvu ya R iyeneranso kuganiziridwa. Chotsatira ndi kusintha kwa CDR3 ndi kukana kwa mndandanda. Zitha kuwoneka kuti kukana kwa mndandanda kukakhala kochepa, CDR3 imakhala yayikulu.

Chomaliza koma chofunika kwambiri, zotsatira za silicon modulator sizili zoyipa kwambiri kuposa za LiNbO3. Monga momwe chithunzi chili pansipa chikusonyezera, CDR3 yamodulator ya siliconZidzakhala zapamwamba kuposa za LiNbO3 ngati pali kusiyana kwakukulu kudzera mu kapangidwe koyenera ka kapangidwe ndi kutalika kwa modulator. Mikhalidwe yoyesera imakhalabe yofanana.

Mwachidule, kapangidwe kake ka modulator ya kuwala kwa silicon kangathe kuchepetsedwa kokha, osati kuchiritsidwa, ndipo ngati kangagwiritsidwe ntchito mu dongosolo la FMCW kumafunika kutsimikiziridwa koyesera, ngati kungakhaledi, ndiye kuti kangathe kuphatikiza ma transceiver, komwe kuli ndi ubwino wochepetsera ndalama zambiri.