L BANDI DÖNGÜ TİPİ ERBİYUM KATKILI FİBER AMPLİFİKATÖR VE ASE KAYNAĞI Ahmet ALTUNCU Arif BAŞGÜMÜŞ Fotonik Araştırma Laboratuvarı mf.dumlupinar.edu.tr/~fotonik Dumlupınar Üniversitesi, Mühendislik Fakültesi Elektrik-Elektronik Mühendisliği, KÜTAHYA Aralık 2005 Hello everyone! I m Arif Başgümüş. I m going to present DESIGN AND CHARACTERIZATION OF HIGH PERFORMANCE C AND L BAND ERBIUM DOPED FIBER AMPLIFIERS. And this project was funded by State Planning Organization (DPT) in Turkey.

Tek Modlu Fiberde (SMF) İletim Bandları SMF zayıflama eğrisi 700 1300 1100 900 1700 nm 1500 Görülebilir Kızılötesi “L” Bandı ~ 1570 - 1610 nm “O” Bandı ~ 1270-1350 nm “C” Bandı ~ 1530 - 1565 nm “S” Bandı ~ 1470 - 1500 nm “E” Bandı ~ 1370 - 1440 nm First of all, I would like to mention about present transmission bands and attenuation spectrum in single mode fiber. The wavelength region of single mode fiber with the lowest attenuation is called third window or 1.55 µm window. Because of low attenuation, erbium doped fiber amplifiers have been initially developed for optical signal amplification in the conventional band (C band, 1525-1565 nm). And now, they are under investigation to cover the long wavelength band (L-band, 1565-1620 nm) with an inherent flat gain spectrum. A combined C and L bands will offer a much wider transmission window for the dense WDM systems. Şekil 1. Işık Spektrumu Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

İletim Bandlarının Kanal Kapasiteleri Tablo 1. Kanal Kapasiteleri DWDM Kanal Aralıkları 20 nm 12.5 GHz 25 GHz 50 GHz 100 GHz CWDM 18* “O” Band “S” Band** 320*** 160*** 80 40 “C” Band “L” Band “E” Band 530*** 280*** 140*** 70*** First of all, I would like to mention about present transmission bands and attenuation spectrum in single mode fiber. The wavelength region of single mode fiber with the lowest attenuation is called third window or 1.55 µm window. Because of low attenuation, erbium doped fiber amplifiers have been initially developed for optical signal amplification in the conventional band (C band, 1525-1565 nm). And now, they are under investigation to cover the long wavelength band (L-band, 1565-1620 nm) with an inherent flat gain spectrum. A combined C and L bands will offer a much wider transmission window for the dense WDM systems. * 1311 nm altındaki iki dalgaboyu şu anda sağlanamıyor. ** Bu bandda ticari olarak sağlanabilen amplifikatör mevcut değil. *** Teorik kanal sayısı Standartlar : DWDM : ITU G.694.1 CWDM : ITU G.694.2 Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

L Band EDFA’da Optik Sinyal Amplifikasyonunun Karakteristikleri Temel karakteristikler : L bandında düşük popülasyon tersbirikimi : ~ % 40 C bandında : > % 70 Daha uzun erbiyum katkılı fiber gereksinimi : 50 ~ 100 m C bandında : 5 ~ 10 m Daha yüksek pompalama gücü : 100 ~ 200 mW C bandında : 50 ~ 100 mW Pompa dönüşüm verimini (PCE) artırmak için kullanılan özel teknikler : L-EDFA’ya C bandı çekirdek sinyal enjeksiyonu C bandındaki geri yönlü ASE’nin L-EDFA’ya yeniden uygulanması L bandı sinyal için çift geçişli veya üç geçişli konfigürasyon kullanılması Döngü tipi L-EDFA konfigürasyonu kullanılması There are three fundamental requirements to provide sufficient gain in L band. Firstly……, secondly…. and thirdly…. In addition, in order to increase the power conversion efficiency (PCE) from pump to signal band, a number of special techniques can be used. Firstly……, secondly ………, and thirdly………… Some other techniques can also be used to increase gain in L band. Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

Simülasyon Sonuçları (a) Kazanç Spektrumu In the simulations, the total bidirectionally applied pump power was 2x150 mW and the signal input power was -30 dBm for each channel assuming 100 WDM channels in total from 1520 nm to 1635 nm. Figures 4a and b show the gain and noise figure spectra of bidirectionally pumped EDFA with different fiber lengths varying from 5 m to 100 m. For short fiber lengths (5-10 m), the EDFA operates completely in C band. When the EDF length increases to longer than 30 m, the gain spectrum of the EDFA shifts to longer wavelength band (L band) and gives almost no gain in C band. The gain spectrum shift is nearly proportional to EDF length although the net gain decreases for longer lengths than 75 m due to insufficient pumping conditions. For short fiber lengths (5-10 m), the noise figure of the EDFA is as low as 4 dB due to high gain of the C band EDFA. On the other hand, the low noise region of the amplifier also shifts to longer wavelength region for longer lengths and the noise figure is higher with respect to C band. (a) Kazanç Spektrumu (b) Gürültü Faktörü Spektrumu Şekil 3. 980 nm’de çift yönlü pompalanan bir EDFA’da kazanç ve gürültü faktörü spektrumlarının fiber uzunluğu ile değişimi. (Pp = 2x 150 mW, Psig = -30 dBm, 1520-1635 nm arasında 100 WDM kanal varsayılmaktadır.) Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

Metro-12 EDF Parametreleri Tablo 2. Metro-12 erbiyum katkılı fiber parametreleri NA 0.21 Kesim Dalgaboyu 960 nm İyon Yoğunluğu 1.6e25 iyon/m3 Öz yarıçapı 1.75 µm Arkaplan Kaybı 8 dB/km @ 1310 nm Absorplama Kaybı 10.46 dB/m @ 980 nm 7.28 dB/m @ 1480 nm 17.70 dB/m @ 1530 nm Emisyon Kaybı 2.01 dB/m @ 1480 nm 16.59 dB/m @ 1530 nm (b) The most important parameters of Metro-12 erbium doped fiber manufactured by Fibercore Company used in both the simulations and the experiments are shown in Table 1. The parameters such as numeric aperture, Cutoff Wavelength, Ion Concentration, Core radius, Background loss, absorption loss and emission loss are given. Figure 2a shows absorption spectrum for 980 nm pumping band and figure 2b shows absorption and emission spectra for 1480 nm pumping and 1550 nm signal bands. Both figures are given for Metro-12 erbium doped fiber. Şekil 2. Metro-12 EDF için absorplama ve emisyon spektrumu a) 980 nm pompalama bandı için absorplama spektrumu b) 1480 nm pompalama ve 1550 nm sinyal bandları için absorplama ve emisyon spektrumu. Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

L Bandı Döngü Tipi EDFA The experimental setup of a bidirectionally pumped L band EDFA is shown in figure 10. Here, a fabry perot laser operating at 1550 nm was used as a C band seed signal source. TLS output signal and C-band seed signal are combined via a 90/10 coupler and this combined signal is applied to the L band EDFA pumped bidirectionally at 980 nm. Erbium doped fiber length used in L band EDFA was 50 m. The maximum pump power applied in L-EDFA was 205.6 mW with 114.8 mW in forward and 90.8 mW in backward directions giving a forward/total pumping ratio of 0.56. Şekil 4. Çift yönlü pompalamalı ve çekirdek sinyal uygulanan L bandı döngü tipi EDFA Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

Çekirdek Sinyal Enjeksiyonunun Etkileri The backward ASE spectrum of forward pumped conventional L band EDFA is shown in Fig.12 with the inset showing the backward ASE spectrum of the amplifier without applying a seed signal. Using forward seed signal, C band backward ASE generated at the input part of L-EDFA is used to amplify forward C band seed signal which is further used to pump L band signal. Specifically, C band backward ASE energy at around 1535 nm is mostly transferred to C band forward pump at around 1550 nm, and partly to C band backward ASE at around 1550 nm when the C band signal injection varied between 1540 nm to 1560 nm. Therefore, a C band seed signal injection provides the efficient use of pump power to amplify L band signal only. Şekil 5. İleri yönde pompalanan L-Bandı EDFA’da geri yönlü ASE spektrumunun çekirdek sinyal dalgaboyu ile değişimi. Üstteki şekil : Çekirdek sinyal uygulanmadan elde edilen geri yönlü ASE spektrumu. Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

L Bandı Döngü Tipi EDFA Deneysel Sonuçları-1 Fig.13 shows gain and noise figure performance of L band EDFA as a function of total pump power. The applied pump power was varied from 125 mW to 205 mW which was the maximum power provided in our setup. It can be seen from the figure that, the gain increases and begins to saturate at the maximum pump power applied. On the other hand , NF decreases with increasing pump power and takes its lowest value. Şekil 6. Klasik ve döngü tipi L-EDFA konfigürasyonları için kazanç ve gürültü faktörünün toplam pompa gücü ile değişimi. (Psig.in = -30 dBm, sig = 1585 nm) Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

L Bandı Döngü Tipi EDFA Deneysel Sonuçları-2 Fig.14 shows gain and noise figure variations as a function of input signal power for L band EDFA. As seen in the figure, gain saturation occurs from approximately -20 dBm signal input power. At a saturating signal level of -5 dBm, the measured gain is 7.7 dB and noise figure 7.9 dB. Şekil 7. Klasik ve döngü tipi L-EDFA konfigürasyonları için kazanç ve gürültü faktörünün sinyal dalgaboyu ile değişimi. (Psig.in = -30 dBm, Pp.tot = 205.6 mW) Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

L Bandı Döngü Tipi EDFA Deneysel Sonuçları-3 Fig.15 shows the measured gain and noise figure spectra of L-EDFA between 1565-1585 nm. The spectral gain and NF measurements were limited to 1585 nm at L band due to unavailability of the TLS operation beyond this wavelength. It can be seen on the figure that the L-EDFA gain increases with increasing wavelength up to 1585 nm. Although the gain and NF performance of L-EDFA at 1565-1570 nm is worse, they become moderate at 1585 nm as 18.3 dB and 7.1 dB, respectively. From the output ASE spectrum of L-EDFA observed on OSA, the L-EDFA design is estimated to provide an approximately 40 nm gain bandwidth between 1570-1610 nm for saturating signal powers. Şekil 8. Klasik ve döngü tipi L-EDFA konfigürasyonları için kazanç ve gürültü faktörünün giriş sinyal gücü ile değişimi. (sig = 1585 nm, Pp.tot = 205.6 mW) Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

ASE (Amplified Spontaneous Emission) Işık Kaynakları Performans Kriterleri : Genişband çalışabilme Yüksek çıkış gücü Düşük spektral dalgalanma Kısa koherens uzunluğu Uzun dönemde kararlılık Uygulama Alanları : DWDM komponent ve EDFA karakterizasyonu Spektrum dilimlenmiş WDM kaynak Fiber optik jiraskop Optik sensör sistemleri Düşük koherensli tomografi The experimental setup of a bidirectionally pumped L band EDFA is shown in figure 10. Here, a fabry perot laser operating at 1550 nm was used as a C band seed signal source. TLS output signal and C-band seed signal are combined via a 90/10 coupler and this combined signal is applied to the L band EDFA pumped bidirectionally at 980 nm. Erbium doped fiber length used in L band EDFA was 50 m. The maximum pump power applied in L-EDFA was 205.6 mW with 114.8 mW in forward and 90.8 mW in backward directions giving a forward/total pumping ratio of 0.56. Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

Band Seçilebilir Genişband Döngü Tipi ASE Kaynağı The experimental setup of a bidirectionally pumped L band EDFA is shown in figure 10. Here, a fabry perot laser operating at 1550 nm was used as a C band seed signal source. TLS output signal and C-band seed signal are combined via a 90/10 coupler and this combined signal is applied to the L band EDFA pumped bidirectionally at 980 nm. Erbium doped fiber length used in L band EDFA was 50 m. The maximum pump power applied in L-EDFA was 205.6 mW with 114.8 mW in forward and 90.8 mW in backward directions giving a forward/total pumping ratio of 0.56. Şekil 9. Band seçilebilir genişband döngü tipi ASE kaynağı Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

Klasik Çift Geçişli Geniş Band ASE Kaynak Konfigürasyonları Şekil 10. Geniş band fiber yansıtıcılı klasik çift yönlü pompalamalı çift geçişli ASE kaynağı. The experimental setup of a bidirectionally pumped L band EDFA is shown in figure 10. Here, a fabry perot laser operating at 1550 nm was used as a C band seed signal source. TLS output signal and C-band seed signal are combined via a 90/10 coupler and this combined signal is applied to the L band EDFA pumped bidirectionally at 980 nm. Erbium doped fiber length used in L band EDFA was 50 m. The maximum pump power applied in L-EDFA was 205.6 mW with 114.8 mW in forward and 90.8 mW in backward directions giving a forward/total pumping ratio of 0.56. Şekil 11. C bandı fiber Bragg ızgarası yansıtıcılı klasik çift yönlü pompalamalı çift geçişli ASE kaynağı. Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

Band Seçilebilir Döngü Tipi ASE Kaynağı Deneysel Sonuçları-1 The experimental setup of a bidirectionally pumped L band EDFA is shown in figure 10. Here, a fabry perot laser operating at 1550 nm was used as a C band seed signal source. TLS output signal and C-band seed signal are combined via a 90/10 coupler and this combined signal is applied to the L band EDFA pumped bidirectionally at 980 nm. Erbium doped fiber length used in L band EDFA was 50 m. The maximum pump power applied in L-EDFA was 205.6 mW with 114.8 mW in forward and 90.8 mW in backward directions giving a forward/total pumping ratio of 0.56. Şekil 12. Döngü tipi ASE kaynakta çıkış ASE spektrumunun çekirdek sinyal gücü ile değişimi. Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

Band Seçilebilir Döngü Tipi ASE Kaynağı Deneysel Sonuçları-2 The experimental setup of a bidirectionally pumped L band EDFA is shown in figure 10. Here, a fabry perot laser operating at 1550 nm was used as a C band seed signal source. TLS output signal and C-band seed signal are combined via a 90/10 coupler and this combined signal is applied to the L band EDFA pumped bidirectionally at 980 nm. Erbium doped fiber length used in L band EDFA was 50 m. The maximum pump power applied in L-EDFA was 205.6 mW with 114.8 mW in forward and 90.8 mW in backward directions giving a forward/total pumping ratio of 0.56. Şekil 13. Farklı ASE kaynak konfigürasyonları için ölçülen çıkış ASE spektrumları. a) Çekirdek sinyalsiz döngü ASE kaynağı b) Çekirdek sinyal ile döngü ASE kaynağı c) C bandı FBG yansıtıcılı klasik çift yönlü ASE kaynağı d) Genişband fiber yansıtıcılı klasik çift yönlü ASE kaynağı (optimize edilmiş yansıma oranı ile) (Tüm deneylerde Pp.tot = 230.6 mW) Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

Band Seçilebilir Döngü Tipi ASE Kaynağı Deneysel Sonuçları-3 The experimental setup of a bidirectionally pumped L band EDFA is shown in figure 10. Here, a fabry perot laser operating at 1550 nm was used as a C band seed signal source. TLS output signal and C-band seed signal are combined via a 90/10 coupler and this combined signal is applied to the L band EDFA pumped bidirectionally at 980 nm. Erbium doped fiber length used in L band EDFA was 50 m. The maximum pump power applied in L-EDFA was 205.6 mW with 114.8 mW in forward and 90.8 mW in backward directions giving a forward/total pumping ratio of 0.56. Şekil 14. Döngü tipi ASE kaynakta -10 dB çizgi genişliği ve ortalama dalgaboyunun çekirdek sinyal gücü ile değişimi. (Pp.tot = 230.6 mW) Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

Band Seçilebilir Döngü Tipi ASE Kaynağı Deneysel Sonuçları-4 Çekirdek sinyalsiz döngü ASE kaynağı Çekirdek sinyalli döngü ASE kaynağı C bandı FBG yansıtıcılı klasik DP ASE kaynağı Genişband fiber yansıtıcılı klasik DP ASE kaynağı P 6 dB 7.6 dB 11.2 dB 9 dB Po +11.3 dBm +10.5 dBm +15.27 dBm  41.2 nm 85 nm 79.8 nm 85.6 nm m 1545.8 nm 1566.4 nm 1564.8 nm 1566.6 nm The experimental setup of a bidirectionally pumped L band EDFA is shown in figure 10. Here, a fabry perot laser operating at 1550 nm was used as a C band seed signal source. TLS output signal and C-band seed signal are combined via a 90/10 coupler and this combined signal is applied to the L band EDFA pumped bidirectionally at 980 nm. Erbium doped fiber length used in L band EDFA was 50 m. The maximum pump power applied in L-EDFA was 205.6 mW with 114.8 mW in forward and 90.8 mW in backward directions giving a forward/total pumping ratio of 0.56. Tablo 3. Döngü tipi ASE kaynak ve klasik çift geçişli (DP) ASE kaynak konfigürasyonlarının kıyaslanması Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

Sonuçlar Döngü tipi L bandı EDFA’da : C bandı çekirdek sinyal enjeksiyonu, geri yönlü C bandı ASE’de önemli ölçüde azalmaya neden olmaktadır. Maksimum azalma, 1540-1560 nm çekirdek sinyal dalgaboyu aralığında ve -15 dBm ‘den daha yüksek çekirdek sinyal güçleri için gerçekleşmektedir. L bandı EDFA’da döngü konfigürasyonu ve C bandı çekirdek sinyali kullanılarak klasik L-EDFA tasarımına göre 1585 nm’de, 9.5 dB kazanç artışı ve 2.6 dB gürültü faktörü artışı elde edilmiştir. Döngü tipi genişband ASE kaynağı’nda : -12 dBm ‘den daha düşük, -12 dBm ile -3 dBm arası ve -3 dBm’den daha yüksek çekirdek sinyal güçleri için sırasıyla band seçilebilir C, C+L veya L bandı çalışma modları elde edilmiştir. C+L bandında yüksek bandgenişliği (~ 85 nm), yüksek çıkış gücü (~ +10.5 dBm) ve düşük güç salınımı (7.6 dB) elde edilmiştir. Ahmet Altuncu, Arif Başgümüş, Dumlupınar Üniversitesi

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