• 沒有找到結果。

115 Gbit/s downstream and 10 Gbit/s upstream TWDM-PON together with 11.25 Gbit/s wireless signal utilizing OFDM-QAM modulation

N/A
N/A
Protected

Academic year: 2021

Share "115 Gbit/s downstream and 10 Gbit/s upstream TWDM-PON together with 11.25 Gbit/s wireless signal utilizing OFDM-QAM modulation"

Copied!
6
0
0

加載中.... (立即查看全文)

全文

(1)

Regular Articles

115 Gbit/s downstream and 10 Gbit/s upstream TWDM-PON together

with 11.25 Gbit/s wireless signal utilizing OFDM-QAM modulation

C.H. Yeh

a,b,⇑

, C.W. Chow

c

, H.Y. Chen

a

, Y.L. Liu

a

aInformation and Communications Research Laboratories, Industrial Technology Research Institute (ITRI), Chutung, Hsinchu 31040, Taiwan b

Graduate Institute of Applied Science and Engineering, Fu Jen Catholic University, New Taipei 24205, Taiwan

c

Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan

a r t i c l e

i n f o

Article history:

Received 5 November 2013 Revised 10 December 2013 Available online 7 January 2014 Keywords: 40 Gbps PON Optical OFDM Multi-band Pre-chirp

a b s t r a c t

In this work, we propose and investigate a 115 Gbit/s (4  28.75 Gbit/s) downstream and 10 Gbit/s upstream time- and wavelength-division-multiplexing passive optical network (TWDM-PON) together with 11.25 Gbit/s wireless broadcasting signal using multi-band orthogonal-frequency-division-multiplexing (OFDM) modulation within 10 GHz bandwidth. Here, to compensate the power fading and chromatic dispersion in the higher frequency, we utilize a 0.7 chirp parameter Mach–Zehnder modulator (MZM) for the OFDM signal. Hence, negative power penalties of 0.3 and 0.4 dB in the downstream and broadcasting wireless signals; and power penalty of 0.3 dB in the upstream signal are measured at the bit error rate (BER) of 3.8  103after 20 km standard single mode fiber transmission

without dispersion compensation.

Ó 2013 Elsevier Inc. All rights reserved.

1. Introduction

High-speed and high-capacity passive optical networks (PONs) are promising access systems to provide wide bandwidth to end users economically [1,2]. However, in future next generation (NG)-PON, the downstream traffic rate of 40 Gbit/s or even beyond 100 Gbit/s is required owing to the requirement of different broad-band multi-service [3–5]. To achieve 40 Gbit/s passive access, using single wavelength with 40 Gbit/s orthogonal frequency divi-sion multiplexing (OFDM); and time- and wavelength-dividivi-sion- wavelength-division-multiplexing (TWDM) with 4  10 Gbit/s on–off keying (OOK) has been proposed[6,7]. Thus, for the 40 Gbit/s PON access, using OOK modulation on single wavelength in standard reach PON transmission (20 km) is no longer feasible due to the constrains of fiber chromatic dispersion, polarization mode dispersion (PMD), and expensive 40 GHz transceiver[5].

For the future 40–100 Gbit/s PON, to obtain higher traffic rate cost-effectively, the high spectral efficiency of OFDM-QAM modu-lation would be used[8,9]. Recently, 40 Gbit/s OFDM-PON has also been investigated by using broadband OFDM signal[10,11]. How-ever, they required the higher sampling rate of 12 GS/s of digital to analog/analog to digital (DA/AD) conversion for OFDM processing. Besides, the OFDM subcarriers would also be affected in the higher frequency due to the chromatic dispersion and RF power fading.

Therefore, using the positive chirp modulator would enhance the effect of the fiber dispersion and power fading.

OFDM-QAM is a spectral efficient modulation format in which the data is encoding on multiple subcarriers, and the subcarriers are orthogonal to one another. On the other hand, TDM and WDM allow time and wavelength multiplexing of different chan-nels respectively; hence allowing different users to access and share the same communication link. Besides TDM and WDM, OFDM can provide one more degree of freedom by providing sub-wavelength signal multiplexing via orthogonal frequency divi-sion multiple access (OFDMA)[12].

In this demonstration, we proposed and investigate a 115 (4  28.75) Gbit/s downstream and 10 Gbit/s upstream TWDM-PON utilizing multi-band OFDM modulation together with 11.25 Gbit/s wireless broadcasting signal. Here, the proposed TWDM-PON with multi-band OFDM modulation is operated with-in 10 GHz bandwidth. Each OFDM band is modulated at 16-QAM format. Then, the multi-band OFDM channels of each downstream wavelength are employed in 10 GHz bandwidth Mach–Zehnder modulator (MZM) with 0.7 chirp parameter to generate the 28.75 Gbit/s downstream data and 11.25 Gbit/s wireless traffic in the central office (CO). Direct detection is employed to reduce the cost of receiver (Rx) module. Besides, each 16-QAM OFDM band only needs a 5 GS/s sampling rate and 8 bits resolution for DA and AD conversions in practical system to achieve cost-effectiveness. Furthermore, the continuous wave (CW) wavelength in the CO is distributed to the 2.5 GHz bandwidth Fabry–Perot laser diode (FP-LD)-based optical networking unit (ONU) for upstream 16-QAM OFDM modulation. From the experimental results, the

1068-5200/$ - see front matter Ó 2013 Elsevier Inc. All rights reserved.

http://dx.doi.org/10.1016/j.yofte.2013.12.004

⇑Corresponding author at: Information and Communications Research Labora-tories, Industrial Technology Research Institute (ITRI), Chutung, Hsinchu 31040, Taiwan.

E-mail address:yeh1974@gmail.com(C.H. Yeh).

Contents lists available atScienceDirect

Optical Fiber Technology

w w w . e l s e v i e r . c o m / l o c a t e / y o f t e

(2)

downstream and broadcasting wireless negative power penalties of 0.3 and 0.4 dB and upstream penalty of 0.3 dB are observed simultaneously, at the bit error rate (BER) of 3.8  103 after

20 km single mode fiber (SMF) transmission without dispersion compensation due to pre-chirp characteristic of MZM.

2. Experiment and discussions

Fig. 1shows the proposed TWDM-PON architecture using mul-ti-band OFDM modulation architecture. Here, in the CO, four WDM wavelengths (k1, k2, k3, and k4) are utilized for 115 Gbit/s

down-stream and 11.25 Gbit/s wireless broadcasting signals. Besides, four WDM CW wavelengths (k0 1; k 0 2; k 0 3, and k 0

4) are used to

distrib-ute into each ONU for upstream modulation to achieve colorless operation. In addition, the proposed wavelength assignment for the downstream (blue1-band) and upstream signal (red-band) is

also illustrated inFig. 1. The downstream wavelengths and the up-stream wavelengths are spaced by one free spectral range (FSR) of the arrayed waveguide grating in the C-band. Hence, one port of the arrayed waveguide grating can support the two wavelength sig-nals simultaneously due to the spectral periodicity property. There are two methods that can achieve single side band optical signal. The first is using optical IQ modulator which is much expensive then a MZM. The second method is using optical filter. And the signal needs guard band due to the non-ideal transition edge of the filter, it would reduce the bandwidth efficiency and increase the cost of the system.

Fig. 2presents the experimental setup of proposed TWDM-PON system together with wireless broadcasting. In this measurement, a 1540.2 nm wavelength is used to connect to MZM for down-stream modulation. The downdown-stream wavelength will transmit through a blue-/red-band filter (BRF), erbium-doped fiber amplifier (EDFA), a 20 km SMF and a BRF, and then is received by 10 GHz PIN Rx for signal demodulation, as seen inFig. 2.

Fig. 2also shows the schematic spectra of the four-band OFDM modulation for downstream and wireless traffics. Here, the band1

OFDM signal has the bandwidth of 1.526 GHz. The band2to band4

are with the same bandwidths of 2.813 GHz and are up-converted to the frequencies of 3.164, 6.055 and 8.945 GHz by using I-Q mod-ulation, respectively. Here, we used the 4-port IQ mixer from Hit-tite. The RF bandwidths and conversion losses of IQ mixers from band2 to band4are 1 MHz-6 GHz, 4–8.5 GHz and 6–10 GHz, and

7, 7.5 and 7 dB, respectively. Besides, the OFDM band separations are 0.1315, 0.078 and 0.077 GHz respectively.

In this experiment, owing to the limitation of available equip-ment, the measurement of the four-band OFDM signals are sepa-rated into two parts, as illustsepa-rated in Fig. 2. In the first part, band1and band2are generated by the arbitrary waveform

genera-tor1 (AWG1) and arbitrary waveform generator2 (AWG2). In the

second part, band3 and band4 employ the same AWG2. Hence,

the total multi-band OFDM bandwidth is 10.3515 GHz, which can fit into the modulation bandwidth of our 10 GHz MZM. Besides, since each band is set to be orthogonal with one another, there is almost no interference among the adjacent band.

Fig. 2indicates that the first part includes band1and band2(Ch1

and Ch2) signals, and the second part includes band3and band4

sig-nals for the practical downstream OFDM measurements. Here, the band1to band3are utilized for the downstream data, and the band4

is used for broadcasting wireless signal. Moreover, the four-band OFDM signals are using the same modulation of 16-QAM with a fast-Fourier transform (FFT) size of 512 and cyclic prefix (CP) size of 8 (including 7% overhead). The OFDM signals are generated by

AWG by using the MatlabÒprogram. In the proposed OFDM

sys-tem, the sampling rate and DA/AD resolution of 5 GS/s and 8 bit are utilized, respectively. As shown inFig. 2, base-band OFDM sig-nal of band2to band4are IQ modulated by the IQ mixer.

In the first part, the band1OFDM signal is generate by AWG1. It

contains 40 OFDM subcarriers occupying 1.526 GHz bandwidth from 82 MHz to 1.626 GHz to produce a total data rate of 6.25 Gbit/s. The band2OFDM signal consist 72 subcarriers

occupy-ing 2.813 GHz bandwidth to generate a data rate of 11.25 Gbit/s. In the second part, the band3and band4OFDM signals are generated

by using AWG2, and each band also consists of 72 OFDM

subcarri-ers occupying 2.813 GHz bandwidth for producing a data rate of 11.25 Gbit/s. The multi-band OFDM signal could be applied to the MZM with the alpha chirp parameters of 0.7. As a result, the downstream data of 28.75 Gbit/s and broadcasting wireless of 11.25 Gbit/s at 8.945 GHz can be generated simultaneously by the proposed four-band OFDM modulation.

In the experiment, one 3 GHz bandwidth LPFs is employed for band1, four 1.9 GHz bandwidth LPFs are used for band2to band4,

and three BPFs with 3.4 GHz bandwidth are utilized for band2to

band4, as shown in Fig. 2. After 20 km SMF transmission, the

28.75 Gbit/s downstream and 11.25 wireless signals are directly detected by a PIN Rx. The PIN Rx has a 3 dB bandwidth of 12 GHz. It has the responsivity of 0.9 A/W at wavelength of 1550 nm. The dark current is about 5 nA. Besides, a real-time scope is used to capture the received electrical data for off-line analysis. Therefore, the BER would be calculated according to the measured signal-to-noise ratio (SNR) of each OFDM subcarrier.

As we know, the SNR of OFDM subcarrier would drop seriously in high frequency after a length of fiber transmission due to the RF power fading[13]. Here, to realize the relationship of chirp effect and OFDM signal, first we use a 0.53 chirp parameter of electro-absorption modulator (EAM) to experiment the four-band OFDM modulation. First, we use the numerical analysis of RF power fad-ing at the chirp parameter of 0.53 and 0.7 respectively.Fig. 3 pre-sents the numerical result of the power fading under the frequencies from 0 to 10 GHz, when the chirp parameter is 0.53 and 0.7 respectively, after 20 km SMF transmission. As seen in Fig. 3, the power fading could be improved in the higher frequency when the negative chirp parameter is employed. When the fre-quency is 10 GHz under the 0.53 and 0.7 chirp parameters, respectively, the power fading can be obtained in 28.8 and 3.8 dB.

Fig. 4(a) and (b) presents the measured SNR of each OFDM sub-carrier at the back-to-back (B2B) and 20 km SMF transmission un-der the received power of 10 dBm, when the 0.53 chirp parameter EAM and 0.7 chirp parameters MZM is utilized respec-tively. As shown inFig. 4(a), the SNR cannot achieve the forward error correction (FEC) threshold (SNR = 16.5 dB; BER = 3.8  103)

after 20 km fiber transmission, when the OFDM subcarrier

TRx (λλ1) CW (λ′1) WDM TRx (λ′ 1) Central Office Re-ONUs Splitter λ1λ2λ3 λ4 λ′1λ′2λ′3λ′4 Downstream (Blue-Band) Upstream (Red-Band)

WDM

wireless

Fig. 1. Proposed TWDM-PON architecture by using multi-band OFDM modulation architecture. The inset is the proposed wavelength assignment for the downstream and upstream signal.

1

For interpretation of color in Figs. 1 and 2, the reader is referred to the web version of this article.

(3)

frequency is larger than 7.2 GHz due to power fading and chro-matic fiber dispersion. Moreover, the band4(wireless signal) would

be influenced and become worst in 20 km fiber transmission. To solve the issue, while maintaining the 20 km reach of the standard PON together with wireless signal transmission, a 10 GHz MZM with 0.7 chirp parameter is used. The MZM (pro-duced by Eospace) is Z-cut with a fixed pre-chirp alpha chirp parameter of 0.7. The insertion loss and the Vpiof the MZM are

3 dB and 4 V, respectively.Fig. 4(b) shows the SNR of each OFDM subcarrier under the four-band frequency at the B2B and 20 km fiber transmission when the received power is 10 dBm. The ob-served SNR of band3and band4are increased due to

pre-compen-sation via pre-chirp MZM after 20 km SMF transmission, as shown in Fig. 4(b). Moreover, after 20 km transmission, the measured SNRs of OFDM subcarriers in band3and band4are better than that

of B2B status, as seen inFig. 4(b). Besides, the measured SNRs of all four-band OFDM frequency are larger than FEC threshold. Fig. 5 presents the measured electrical power of four-band OFDM at

the B2B status and 20 km fiber transmission. Due to the pre-chirp of MZM in the experiment, the power gain in the OFDM signal of band3and band4can be enhanced after 20 km fiber transmission,

as shown inFig. 5. Therefore, the pre-chirp MZM is very crucial for the proposed 115 Gib/s TWDM-PON architecture with 8.945 GHz wireless signal by employing multi-band OFDM modu-lation to reduce power fading in 20 km SMF transmission. MZM λλ1 λ′1 20km SMF FP-LD Rx OC BRF Rx EDFA EDFA

Band1Band2Band3Band4

0.863 3.16 6.05 8.95 (GHz) Multi-Band OFDM LPF LPF Mixer BPF Amp LO1: 3.16GHz Hybrid 90o Amp AWG1 AWG2 CH1 CH2 LPF LPF LPF AWG1 CH1 CH2 LO2: 6.05GHz LO3: 8.95GHz BPF BPF Band1 Band2 Band3 Band4

Data

Wireless

BRF

Fig. 2. Experimental setup of proposed TWDM-PON system together with wireless broadcasting, and the schematic spectra of the four-band OFDM modulation for downstream and wireless traffics.

α = −0.7 Frequency (GHz) SNR (dB) 0 4 8 12 16 20 24 28 Band1: B2B Band2: B2B Band3: B2B Band4: B2B Band1: 20km Band2: 20km Band3: 20km Band4: 20km SNR@16.5dB α = 0.53 Received Power (dBm) 0 1 2 3 4 5 6 7 8 9 10 11 5 0 1 2 3 4 6 7 8 9 10 11 SNR (dB) 0 4 8 12 16 20 24 28 Band1: 20km Band2: 20km Band3: 20km Band4: 20km Band1: B2B Band2: B2B Band3: B2B Band4: B2B SNR@16.5dB

(a)

(b)

Fig. 4. Measured SNR of each OFDM subcarrier at the B2B and 20 km SMF transmission under the received power of 10 dBm, when (a) the 0.53 chirp parameter EAM and (b) 0.7 chirp parameters MZM is utilized respectively.

Wavelength (GHz) 0 1 2 3 4 5 6 7 8 9 10 Power Fading (dB) -12 -10 -8 -6 -4 -2 0 α = −0.7 α = 0.53

Fig. 3. The numerical result of the power fading under the frequencies from 0 to 10 GHz, when the chirp parameter is 0.53 and 0.7 respectively, after 20 km SMF transmission.

(4)

Fig. 6shows the BER performances of downstream data traffic at the B2B status and 20 km SMF transmission. The total data rate of 28.75 Gbit/s can be obtained from OFDM band1to band3. The Rx

sensitivities of B2B status and 20 km SMF transmission are 17.1 and 17.4 dBm, respectively. The insets are the corresponding con-stellation diagrams at the B2B status and 20 km fiber transmission at the FEC level. As seen inFig. 6, the negative power penalty of 0.3 dB is observed after 20 km fiber transmission by using a 0.7 chirp parameter of MZM. For the wireless signal broadcasting, the 8.945 GHz OFDM band4is also transmission. Here,Fig. 7

pre-sents the BER performances of wireless traffic with 11.25 Gbit/s at the B2B status and 20 km SMF transmission. The power sensitiv-ities of B2B status and 20 km SMF transmission are 16.7 and

17.1 dBm, respectively. And, the insets are the corresponding constellation diagrams at the B2B status and 20 km fiber transmis-sion at the FEC threshold. As seen inFig. 7, the negative power pen-alty of 0.4 dB is observed after 20 km fiber transmission. As a result, the measured negative penalty is due to the pre-chirp char-acteristic as discussed before.

Next, we will discuss the upstream traffic of the proposed TWDM-PON system. As illustrated in Fig. 2, a CW wavelength (k0

1) of 1550.50 nm is distributed from OLT and transmits through

a BRF, EDFA, a 20 km SMF a BRF and an optical circulator (OC) launching into FP-LD of each ONU for mode-locking. Here,Fig. 8 shows the output spectrum of 2.5 GHz FP-LD (blue line) in free-run when the FP-LD is operated at the bias current and tempera-ture of 30 mA and 25 °C. We observe that the maximum peak power of FP-LD is around 1550.55 nm in free-run. When the dis-tributed CW lightwave is launched into FP-LD, the FP-LD would be injection-locked and could be direct modulated. According to the past study, to achieve a better output performance, the injec-tion power into FP-LD should be larger 12 dBm [14]. Thus, Fig. 8 also illustrates the output spectrum of mode-locked FP-LD (red line) when an injection power is 12 dBm. The output wave-length and power of mode-locked FP-LD are measured at 1550.5 nm and 6.5 dBm respectively. Besides, the side-mode sup-pression ratio (SMSR) of 40.4 dB is also obtained, as shown inFig. 8. In this measurement, the upstream mode-locked FP-LD can be direct modulated by employing 16-QAM OFDM modulation to gen-erate 10 Gbit/s upstream data rate. 5 GS/s sampling rate and 8 bit DAC resolution are set by the AWG, and CP of 8 is used. Thus, 128 subcarriers of 16-QAM format occupy nearly 2.5 GHz B2B

Band1 Band2 Band3 Band4

20km 0 2 4 6 8 10 Frequency (GHz) -65 -55 -45 -35 -25 -15 Power (dBm)

Fig. 5. Measured electrical power of four-band OFDM signal at B2B status and 20 km fiber transmission resepectively.

Data Signal

Received Power (dBm)

-19 -18 -17 -16 -15 -14 -13

Bit Error Rate

10-5 10-4 10-3 10-2 10-1 BER@3.8e-3 B2B 20km B2B 20km

Fig. 6. BER performances of downstream data traffic at the B2B status and 20 km SMF transmission. And the insets are the corresponding constellation diagrams.

Wireless Signal

Received Power (dBm)

-19 -18 -17 -16 -15 -14 -13

Bit Error Rate

10-5 10-4 10-3 10-2 10-1 B2B 20km BER@3.8e-3 B2B 20km

Fig. 7. BER performances of wireless traffic with 11.25 Gbit/s at the B2B status and 20 km SMF transmission. And the insets are the corresponding constellation diagrams. free-run Wavelength (nm) 1540 1544 1548 1552 1556 1560 Power (dBm) -70 -60 -50 -40 -30 -20 -10 0 −12 dBm injection 1540 1545 1550 1555 1560 -70 -60 -50 -40 -30 -20 -10 0

Fig. 8. Output spectra of 2.5 GHz FP-LD (blue line) in free-run and mode-locking (red line) when the FP-LD is operated at the bias current and temperature of 30 mA and 25 °C. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

FP-LD@30mA Frequency (GHz) 0.0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 SNR (dB) 0 5 10 15 20 25 30 35 w/o injection w injection BER@3.8e−3

Fig. 9. Measured SNR spectra of each OFDM subcarriers after 20 km SMF transmission, when the FP-LD is without and with mode-locked operation.

(5)

bandwidth from 0.0195 to 2.5195 GHz, with a fast-Fourier trans-form (FFT) size of 512. Here, 19.5 MHz subcarrier spacing and 10 Gbit/s total data rate are achieved. Hence, the produced electri-cal 16-QAM OFDM signal can be applied to the FP-LD via a bias-tee (BT). Then the upstream signal is direct-detected via a 2.5 GHz PIN Rx.

To realize the proposed upstream signal performance, we can measure the SNR of each OFDM subcarriers for the upstream traffic first.Fig. 9shows the measured SNR spectra of each OFDM subcar-riers after 20 km SMF transmission, when the FP-LD is without and with mode-locked operation. As illustrated in Fig. 9, the whole measured SNRs of mode-locked FP-LD can be larger than 16.5 dB (FEC threshold). To achieve 10 Gbit/s 16-QAM OFDM upstream transmission under standard reach of 20 km, the injection-locked FP-LD with 12 dBm injection power must be required. Besides, Fig. 10(a) and (b) shows the measured electrical spectra of the opti-cal OFDM signal, when using 12 dBm injection power launching into the FP-LD, at the B2B state and after 20 km fiber transmission respectively. The FP-LD was dc-based properly. After 20 km fiber transmission, the electrical power would degrade in the higher fre-quency domain due to the power fading and fiber chromatic dispersion.

In the experiment,Fig. 11 presents the BER performances of 10 Gbit/s 16-QAM OFDM upstream traffic at the B2B and after 20 km SMF transmission, respectively. The insets of Fig. 11 are the corresponding constellation diagrams, measuring at the FEC threshold (SNR = 16.5 dB and BER = 3.8  103). Here, the Rx

sensitivities are observed at 17.8 and 17.5 dBm, under the B2B state and 20 km fiber transmission, respectively. Therefore,

the measured power penalty is 0.3 dB, in the fiber transmission of 20 km.

OFDM is a multi-carrier modulation format and it is robust against fiber chromatic dispersion. This is because the symbol per-iod of each subcarrier can be made long compared to the delay spread caused by the group-velocity dispersion (GVD). Previous, we have demonstrated that OFDM-QAM can be used in extended reach PON (100 km) without dispersion compensation[15]. Hence, the proposed approach in this paper can extended the transmission distance to 40 km.

3. Conclusion

We proposed and experimentally investigated a 115 (4  28.75) Gbit/s downstream and 10 Gbit/s upstream TWDM-PON sys-tem together with 11.25 Gbit/s wireless broadcasting at 8.945 GHz by using four-band OFDM modulation within 10 GHz bandwidth. Here, each OFDM channel was modulated at 16-QAM format. Here, there were four WDM downstream wavelengths and four distributed CW wavelengths in the CO. Each downstream wavelength carried 28.75 Gbit/s downstream data and 11.25 Gbit/s wireless signals simultaneously within 10 GHz bandwidth for TWDM-PON access. The four-band OFDM modulation was applied on a 10 GHz band-width MZM with 0.7 chirp parameter to compensate the power fading and fiber chromatic dispersion.

In the measurement, the direct-detection was used to reduce the cost of Rx side. Each 16-QAM OFDM channel only requires the 5 GS/s sampling rate and 5 bits resolution for the DA and AD conversion. Hence, negative penalties of 0.3 and 0.4 dB were measured experimentally for the downstream and wireless trans-missions at the BER of 3.8  103after 20 km fiber transmission

respectively, when a 0.7 chirp parameter of MZM was used in the proposed four-band OFDM modulation for downstream link.

In addition, the distributed CW wavelength was utilized to launch into FP-LD-based ONU for injection-locking to serve as upstream traf-fic. Here, the measured upstream power penalty was 0.3 dB after a fiber transmission of 20 km, when an injection power of 12 dBm was injected into FP-LD. As a result, experimental and numerical analysis of using commercially available EAM and MZM with 0.53 and 0.7 alpha chirp parameter were performed, respectively, show-ing the pre-chirp MZM was very crucial for the proposed OFDM PON to reduce power fading and chromatic dispersion.

References

[1]C.W. Chow, C. H Yeh, K. Xu, J.Y. Sung, H.K. Tsang, TWDM-PON with signal

remodulation and Rayleigh noise circumvention for NG-PON2, IEEE Photon. J. 5 (6) (2013) 7902306.

(a) B2B

(b) 20km

Fig. 10. Measured electrical spectra of the optical OFDM signal, when using 12 dBm injection power launching into the FP-LD, (a) at the B2B state and (b) after 20 km fiber transmission respectively.

Received Power (dBm)

-19 -18 -17 -16 -15 -14 -13

Bit Error Rate

10-5 10-4 10-3 10-2 10-1 B2B 20km BER@3.8e-3 B2B 20km

Fig. 11. BER performances of 10 Gbit/s 16-QAM OFDM upstream traffic at the B2B and after 20 km SMF transmission, respectively. And the insets are the correspond-ing constellation diagrams.

(6)

[2] P.P. Iannone, K.C. Reichmann, Optical access beyond 10 Gb/s PON, in: Proc. of ECOC, 2010, Paper Tu.3.B.1.

[3]C.H. Yeh, C.W. Chow, Y.F. Wu, H.Y. Chen, Demonstrations of 10 and 40 Gbps

upstream transmissions using 1.2 GHz RSOA-based ONU in long-reach access networks, Opt. Fiber Technol. 18 (2) (2012) 63–67.

[4] L.N. Binh, M. Firus, T.N.K. Hoan, 100G DQPSK-remodulation for PON upstream transmission using optical phase locking, in: IEEE ICCS, 2010, pp. 179–183.

[5]C.W. Chow, C.H. Yeh, 40-Gb/s downstream DPSK and 40-Gb/s upstream OOK

signal remodulation PON using reduced modulation index, Opt. Exp. 18 (2010)

26046–26051.

[6]Y. Luo, X. Zhou, F. Effenberger, X. Yan, G. Peng, Y. Qian, Y. Ma, Time- and wavelength-division multiplexed passive optical network (TWDM-PON) for next-generation PON stage 2 (NG-PON2), J. Lightw. Technol. 31 (4) (2013) 587–593.

[7]C.H. Yeh, C.W. Chow, C.H. Hsu, 40 Gb/s time division multiplexed passive

optical networks using downstream OOK and upstream OFDM modulations, IEEE Photon. Technol. Lett. 22 (2010) 118–120.

[8] S. Skafidas, D. Hewitt, Performance and applications of gigabit OFDM over optical fiber systems in metro and access networks, in: Proc. of ECOC, 2006, pp. 429–430.

[9]C.H. Yeh, C.W. Chow, H.Y. Chen, Simple colorless WDM-PON with Rayleigh

backscattering noise circumvention Employing m-QAM OFDM downstream

and remodulated OOK upstream signals, J. Lightw. Technol. 30 (13) (2012)

2151–2155.

[10] D. Qian, N. Cvijetic, J. Hu, T. Wang, 40-Gb/s MIMO-OFDM-PON using polarization multiplexing and direction–detection, in: Proc. of OFC, 2009, Paper OMV3.

[11] D. Qian, S.H. Fan, N. Cvijetic, J. Hu, T. Wang, 64/32/16 QAM-OFDM using direct-detection for 40G-OFDMA-PON downstream, in: Prof. of OFC, 2011, Paper OMG4.

[12]N. Cvijetic, D. Qian, J. Hu, T. Wang, Orthogonal frequency division multiple access PON (OFDMA-PON) for colorless upstream transmission beyond 10 Gb/ s, IEEE J. Sel. Areas Commun. 28 (2010) 781–790.

[13]D.-Z. Hsu, C.-C. Wei, H.-Y. Chen, W.-Y. Li, J. Chen, Cost-effective 33-Gbps intensity modulation direct detection multi-band OFDM LR-PON system employing a 10-GHz-based transceiver, Opt. Exp. 22 (18) (2011) 17546– 17556.

[14]S.-Y. Lin, Y.-C. Su, Y.-C. Li, H.-L. Wang, G.-C. Lin, S.-M. Chen, G.-R. Lin, 10-Gbit/s

direct modulation of a TO-56-can packed 600-lm long laser diode with 2%

front facet reflectance, Opt. Exp. 21 (21) (2013) 25197–25209.

[15]C.W. Chow, C.H. Yeh, C.H. Wang, F.Y. Shih, C.L. Pan, S. Chi, WDM extended

reach passive optical networks using OFDM-QAM, Opt. Exp. 16 (2008) 12096– 12101.

數據

Fig. 1 shows the proposed TWDM-PON architecture using mul- mul-ti-band OFDM modulation architecture
Fig. 4. Measured SNR of each OFDM subcarrier at the B2B and 20 km SMF transmission under the received power of 10 dBm, when (a) the 0.53 chirp parameter EAM and (b) 0.7 chirp parameters MZM is utilized respectively.
Fig. 5. Measured electrical power of four-band OFDM signal at B2B status and 20 km fiber transmission resepectively.
Fig. 10. Measured electrical spectra of the optical OFDM signal, when using 12 dBm injection power launching into the FP-LD, (a) at the B2B state and (b) after 20 km fiber transmission respectively.

參考文獻

相關文件

An n×n square is called an m–binary latin square if each row and column of it filled with exactly m “1”s and (n–m) “0”s. We are going to study the following question: Find

To proceed, we construct a t-motive M S for this purpose, so that it has the GP property and its “periods”Ψ S (θ) from rigid analytic trivialization generate also the field K S ,

obtained by the Disk (Cylinder ) topology solutions. When there are blue and red S finite with same R, we choose the larger one. For large R, it obeys volume law which is same

Hence, we have shown the S-duality at the Poisson level for a D3-brane in R-R and NS-NS backgrounds.... Hence, we have shown the S-duality at the Poisson level for a D3-brane in R-R

Sunya, the Nothingness in Buddhism, is a being absolutely non-linguistic; so the difference between the two "satyas" is in fact the dif- ference between the linguistic and

maintenance and repair works should be carried out by school and her maintenance agent(s) to rectify defect(s) as identified in routine and regular inspections. Examples of works

 name common laboratory apparatus (e.g., beaker, test tube, test-tube rack, glass rod, dropper, spatula, measuring cylinder, Bunsen burner, tripod, wire gauze and heat-proof

 understand and use the English terms for describing the animal types, external features, body parts, feeding habits, movement and habitats of a panda, a crocodile and a crab