ABSTRAKSI: Raman optical amplifier (ROA) merupakan salah satu jenis penguat optik yang juga menghasilkan derau dalam proses penguatannya. Derau yang dimaksud salah satunya adalah amplified spontaneous emission(ASE), yang mana merupakan derau yang tidak bisa dihindari dan pasti muncul pada ROA. Karena itu, perlu adanya filter untuk meredam derau tersebut.
Pada tugas akhir ini, fiber Bragg grating (FBG) dipilih sebagai filter yang digunakan untuk meredam derau ASE pada ROA. Kemudian, analisis mengenai pengaruh yang disebabkan oleh parameter-parameter yang ada terhadap perubahan spektrum Raman gain serta perubahan spektrum daya derau ASE sebelum dan sesudah adanya filter FBG akan dilakukan.
Dengan p = 1450 nm, puncak Raman gain ada di pergeseran Raman 437 cm-1. Raman gain maksimum bernilai 43,3982 dB saat x = 100 mol%, bernilai 6,3433 dB saat L = 100 km, dan bernilai 30,5277 dB saat Pp = 1000 mW. PASE maksimum bernilai 0,098 mW di titik 429 cm-1 saat Pp = 1000 mW, bernilai 0,393 mW di titik 200 cm-1 saat L = 25 km, bernilai 0,2014 mW di titik 200 cm-1 saat x = 12 mol%. Kemudian, saat daya ASE yang muncul pada kondisi L = 100 km, Ps = 1 mW, Pp = 600 mW, dan x = 8,3 mol% diredam (diratakan) dengan filter FBG yang memiliki ng = 5x10-3, B =1545,9 nm, dan N = 180; dihasilkan spektrum derau yang rata dengan lebar pita 8,3352 nm atau 1,0493 THz.
KATA KUNCI: Raman optical amplifier, amplified spontaneous emission, fiber Bragg grating, Raman gainABSTRACT: Raman optical amplifier (ROA) is an optical amplifier that produces noise during the amplifying process. One of the noise is amplified spontaneous emission (ASE), which is a noise that cannot be prevented and is always present in ROA. Because of that reason, a filter is needed to reduce this noise.
In this final project, fiber Bragg grating is chosen to be the filter used to reduce ASE noise in ROA. Then, analysis of the effects caused by existing parameters to Raman gain spectrum change and ASE noise spectrum change before and after FBG filter is performed.
With p = 1450 nm, Raman gain peak is on Raman shift 437 cm-1. Maximum Raman gain is 43.3982 dB when x = 100 mol%, is 6.3433 dB when L = 100 km, and is 30.5277 dB when Pp = 1000 mW. Maximum PASE is 0.098 mW on 429 cm-1 when Pp = 1000 mW, is 0.393 mW on 200 cm-1 when L = 25 km, is 0.2014 mW on 200 cm-1 when x = 12 mol%. Then, when the arising ASE power in a condition of L = 100 km, Ps = 1 mW, Pp = 600 mW, and x = 8.3 mol% is reduced (flattened) with an FBG filter which has ng = 5x10-3, B =1545.9 nm, and N = 180; a flat noise power spectrum is made with a bandwidth of 8.3352 nm or 1.0493 THz.
KEYWORD: Raman optical amplifier, amplified spontaneous emission, fiber Bragg grating, Raman gain