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Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 20, Iss. 8 — Apr. 9, 2012
  • pp: 9019–9030
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Characterization of highly-sensitive and fast-responding monitoring module for extended-reach passive optical networks

Elaine Wong and Ka-Lun Lee  »View Author Affiliations


Optics Express, Vol. 20, Issue 8, pp. 9019-9030 (2012)
http://dx.doi.org/10.1364/OE.20.009019


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Abstract

The extended-reach broadband access network is widely acknowledged as a future-proof solution to providing bandwidth-intensive services to an increased number of users spread across a large geographical area. To address fiber failure detection and reliability issues specific to these networks, a simple automatic protection switching and pump laser shutdown scheme that exploits the use of highly-sensitive and fast-responding monitoring modules is proposed and experimentally demonstrated in this work. We also present an analytical model that describes the probability distribution function of the response time, thus allowing the mean response time, jitter, and sensitivity to be evaluated. Our results show a high sensitivity of < −50 dBm can be achieved, thus allowing the module to be applied in topologies with extended reach and/or split ratio beyond that of conventional PONs.

© 2012 OSA

1. Introduction

To address fiber failure detection and reliability issues specific to ER-PONs, we propose a simple automatic protection switching and pump laser shutdown scheme that is based on a low-cost, highly-sensitive, and fast-responding monitoring module. Our proposal exploits (a) distributed Raman amplification, (b) optical loopback of the continuous downstream signal, and (c) a highly-sensitive and fast-responding monitoring module to detect fiber failure with minimal delay. Distributed Raman amplification provides an easily-tailored flat optical gain bandwidth that exceeds that of common optical amplifiers [8

8. K. L. Lee, J. L. Riding, A. V. Tran, and R. S. Tucker, “Extended-reach GPON for rural areas using distributed raman amplfiers,” in Proc. IEEE/OSA Opt. Fiber Communication Conference, San Diego, CA, NME3 (2009).

] while the optically looped-back downstream signal functions as a reflected monitoring signal. The output from the monitoring module triggers an optical switch for protection switching and/or the Raman amplifier interlock for amplifier shutdown which in our proposal is facilitated by the shutdown of the Raman amplifier pump lasers. In this paper, we present experimental results that show automatic protection switching and automatic pump laser shutdown (APLS) within 12 and 2 ms respectively of fiber failure detection. We also present an analytical model to describe the response time probability distribution function, RTPDF(t), of the module to evaluate its mean and jitter, and the minimum received optical power Popt for reliable operation. Here, the minimum Popt for reliable operation is referred to as the sensitivity of the monitoring module. Results highlight a mean response time dependency on Popt and a sensitivity of −51.75 dBm (experiment) and −51.5 dBm (theory), allowing the monitoring module to be applied in topologies with extended reach and/or split ratio beyond that of conventional PONs.

2. Principal of operation

The automatic protection switching and APLS scheme proposed in this work can be applied to distributed Raman amplified ER-PONs supporting either single channel (e.g. standardized 1Gb/s PON systems and standardized 10 Gb/s PON systems) or multiple wavelength (WDM-PON) channels. These two architectures are schematically shown in Figs. 1(a)
Fig. 1 Distributed Raman amplified ER-PONs supporting either (a) single (e.g. Ethernet PON and Gigabit PON) or (b) multiple wavelength (WDM-PON) channels. (c) Block diagram of monitoring module with probability distribution function, RTPDF, of the control signal.
and 1(b), respectively. In Fig. 1(a), the ER-PON supports a single upstream and a single downstream wavelength channel, in which bandwidth is shared between multiple optical network units (ONUs) located at subscriber premises. In Fig. 1(b), different wavelength channels are multiplexed at the CO and transmitted simultaneously through a feeder fiber to a WDM demultiplexer which is typically an arrayed waveguide grating (AWG). The AWG separates the multiplexed channels into individual wavelength channels. Each wavelength channel is then further optically power split into multiple distribution fibers, each connected to an ONU. Network reliability is implemented via duplicating the feeder and/or distribution fibers but unlike previously described schemes, here we do not require any additional monitoring light source(s). Instead, the continuous downstream signal is reused as a monitoring signal.

All active components such as the pump lasers of the distributed Raman amplifier and monitoring module, are located at the CO (shown inset of Figs. 1(a) and 1(b)). This feature gives rise to a purely passive plant that eliminates potential power outages in the field. The CO establishes two optical paths, namely the primary and protection paths, via an optical switch that is connected to two feeder fibers. At each splitter, an optical loopback via two connected output ports reflects a fraction of the continuous downstream signal back to the CO for detection at a corresponding monitoring module. Under normal operation, the optical switch is in BAR state with downstream and upstream transmissions traversing the primary path and with the monitoring signal traversing the protection path. Under protection operating conditions, the optical switch is in CROSS state, diverting all traffic onto the protection path.

The presence and absence of the monitoring signal reflected from each optical splitter is detected by a highly-sensitive and fast-responding monitoring module. In Fig. 1(b), identical monitoring modules can be applied to detect each wavelength channel since wavelength demultiplexing is performed prior to the individual inputs of the monitoring modules. Figure 1(c) illustrates a simplified block diagram of the monitoring module which is based on a low bandwidth optical baseband detector [16

16. E. Wong and M. A. Summerfield, “Sensitivity evaluation of baseband carrier-sense circuit for optical CSMA/CA packet networks,” J. Lightwave Technol. 22(8), 1834–1843 (2004). [CrossRef]

]. The module encompasses a second order transimpedance front-end, a first order low pass filter (LPF), two voltage amplifiers, a voltage limiter, and a decision circuit with a preset threshold voltage. The transimpedance front-end is designed to have a high transimpedance gain GF of 118 dBΩ to achieve high signal-to-noise ratio. The bandwidth of the LPF, Δf, designed to be approximately 100 kHz, is the most narrowband of all components in the circuit and hence determines the overall bandwidth of the circuit. A high bandwidth circuitry is not required as the goal of the module is to detect the envelope of the monitoring signal rather than its data. The parameter Δf was also intentionally chosen to be much lower than the bit-rate of the incoming monitoring signal to remove transient oscillations and data pattern variations, thereby eliminating erroneous triggering of the decision circuit and increasing the sensitivity of the monitoring module. The voltage amplifier further amplifiers the low pass filtered signal. In the event of a fiber break which results in the absence of the monitoring signal, the accumulative gain of the voltage amplifiers, namely G1 and G2 respectively, is designed such it would be insufficient to amplify the residual dark current of the PIN photodiode plus any additive noise to cross the decision threshold. The voltage limiter ensures that only the base of the amplified signal is fed into thedecision circuit to prevent saturation of the operational amplifier in the decision circuit. The decision circuit is designed with hysteresis to prevent oscillations in the output from noise. In the event of a fiber failure, the absence of the monitoring signal causes the output of the module to transition from a ‘1’ to a ‘0’ level. This transition triggers the optical switch into CROSS state which then diverts traffic from the primary to the protection path.

The control signal from the monitoring module output can also be utilized to control the amplifier interlock of the Raman pump lasers to facilitate APLS. According to the IEC60825-2 standard for laser safety in optical transmission systems, automatic laser shutdown mechanisms must be fully engaged within 1 second and 3 seconds of fiber/device/connector failure for unrestricted and restricted areas, respectively [15

15. ITU-T G.664, Optical Safety Procedures and Requirements for Optical Transport Systems, 2003, ITU.

, 17

17. K. Hinton, P. Farrell, A. Zalesky, L. Andrew, and M. Zukerman, “Automatic laser shutdown implications for all optical data networks,” J. Lightwave Technol. 24(2), 674–680 (2006). [CrossRef]

]. Accidental laser exposure that is confined to the CO will require the APLS to be activated within 3 seconds. By comparison, feeder fiber failure outside the confines of the CO will require the APLS to be activated within 1 second of fiber failure. We show in this work that both 3 second and 1 second shut down requirements are met through using our proposed APLS.

Observe that the detection of distribution fiber failures and subsequent protection switching were not considered in our current work as such events do not pose a risk of hazardous high power laser exposure. It is expected that exposure of laser light at fiber cuts that are located after the optical splitter are of low optical power due to high optical splitting losses. While clearly out of the scope of our current work, the detection of distribution fiber failures and subsequent protection switching are important and warrant further work.

3. Experimental setup

3.1 Proof-of-concept demonstration

Figure 2
Fig. 2 Experimental setup for network performance measurements. Inset: Optical spectra and Raman gain profile of up- and downstream signals.
illustrates the experimental setup utilized to demonstrate and verify the proposed automatic protection switching and APLS scheme. As a proof-of-concept, a single wavelength 32 split ER-PON configuration representing the network in Fig. 1(a) is experimentally demonstrated and reported in this paper. At the CO, a distributed feedback (DFB) laser is directly modulated with a 231-1 pseudorandom bit sequence (PRBS) non-return-to-zero (NRZ) data from a bit-error-rate testset (BERT) at 1.25 Gb/s. The downstream signal (λD = 1534.2 nm with ~1 mW average output power) is combined with Raman pump light via a coarse WDM filter. The pump lasers comprise two 1450 nm grating stabilized lasers which polarized outputs are multiplexed together. The combined light first traverses an optical switch and an external passive plant comprising a 50 km of feeder fiber link, a 2 × 32 optical splitter implemented with an optical loopback, and a 20 km distribution fiber link. At each ONU, an optical circulator directs downstream signals towards the receiver whilst upstream signals are launched into the passive plant from a low-power and uncooled vertical cavity surface emitting laser (VCSEL). The VCSEL (Ibias = 5.9 mA, λU = 1531.1 nm, average output power of ~0.5 mW) is directly-modulated with 231-1 PRBS NRZ data at 1.25 Gb/s from a second BERT. For data recovery of both downstream and upstream signals, an optical bandpass filter (BPF, ƒ3dB = 1.8 nm), is used to remove the Raman pump and backscattered light before detection using a photoreceiver. In turn, the photoreceiver comprises a 2.5 Gb/s avalanche photodiode, a wideband preamplifier and an inverting-limiting amplifier.

In Fig. 2, the optical loopback at the optical splitter reflects a fraction of the continuous downstream signal, i.e. monitoring signal, back towards the CO and monitoring module via a second 50 km feeder fiber link. At the monitoring module, a BPF (ƒ3dB = 1.8 nm) tuned to λD filters out the reflected monitoring signal from the combined spectra of Raman pump lasers and upstream signal. The output from this monitoring module controls the TTL input of the optical switch. The optical spectra measured at locations A (at upstream receiver), B (downstream receiver), and C (at monitoring module) of the experimental setup are shown inset of Fig. 2.

3.2 Network performance measurements

Bit-error-ratio (BER) measurements of the downstream and upstream signals of the experimental setup in Fig. 2 are plotted in Figs. 3(a)
Fig. 3 Bit-error-ratio (BER) measurements of upstream and downstream signals.
and 3(b), respectively. The eye diagrams measured at BER = 10−9 for the respective signals traversing the protection path are shown inset. Back-to-back (B2B) BER measurements were compared to BER measurements of fiber transmissions on the primary path with the optical switch in BAR state, and protection path with the optical switch in CROSS state. Using the standard measurement of BER < 10−9 to represent error-free transmission, both downstream (CO to ONU) and upstream (ONU to CO) BER measurements indicate negligible penalty for transmissions of signals on the protection path as compared to the primary path, i.e. 0 dB for downstream signals and 0.2 dB for upstream signals measured at BER = 10−9.

Observe in Fig. 2 that the optical loopback at the optical splitter also reflects a fraction of the continuous downstream signal back onto the primary path. Therefore, BER measurements of transmissions through a conventional PON with and without optical loopback were also performed to study the impact of the reflected monitoring signal on signal transmissions on the primary path. Results indicate that in the presence of the reflected monitoring signal, the penalty on signal transmissions on the primary is minimal, i.e. 0.2 dB for downstream signals and 0.4 dB for upstream signals measured at BER = 10−9.

3.3 Response time measurements

Figures 4(a)
Fig. 4 Experimental setup to evaluate response time of (a) monitoring module and optical switch, and (b) automatic pump laser shutdown (APLS) mechanism.
and 4(b) illustrate the experimental setup used to measure the response time of the protection switching and APLS scheme, respectively. In both setups, a burst packet driver and transmitter is used to generate a series of optical packets. These optical packets represent the continuous monitoring signal that is to be detected by the monitoring module. Whenever an optical packet is detected, both optical switch and amplifier interlock are at default positions. A fiber failure is indicated by the absence of an optical packet at the monitoring module, subsequently triggering the optical switch to CROSS state and/or activating APLS.

Figure 5(a)
Fig. 5 Oscilloscope traces measuring response time of (a) monitoring module and (b) optical switch.
compares the measured oscilloscope traces of the falling edge of an incoming optical packet and the resulting monitoring module output. At a received optical power (Popt) of −50.5 dBm, the monitoring module transitions from ‘1’ to ‘0’ within a fast response time of ~524 ns. Figure 5(b) compares the oscilloscope traces measured at the monitoring module output and optical switch outputs. Upon a ‘1’ to ‘0’ transition, signals are switched from theprimary to the protection path, showing a fast response time of 10.5 ms. Considering the worst case scenario where fiber failure occurs just outside the central office, the total protection switching time will be less than 12 ms (~0.5 ms roundtrip propagation delay + 524 ns monitoring module response time + 10.5 ms optical switch response time). In our experiments, it was observed that there exists a dependency of the monitoring module response time and jitter on Popt. While this dependency and jitter will be theoretically characterized and discussed next, it is important to note that for practical values of Popt, the total protection switching time is demonstrated to be dominated by the response time of the optical switch (on a millisecond timescale) rather than that of the monitoring module (on a sub-millisecond timescale).

The APLS response time is measured using the setup shown in Fig. 4(b). The resulting oscilloscope traces of the monitoring module output at a ‘1’ to ‘0’ transition (representing fiber failure) and that at the output of the photodetector are shown in Fig. 6
Fig. 6 Oscilloscope traces measuring the response time of the automatic pump laser shutdown (APLS) mechanism.
. Figure 6(a) shows that without amplification, the signal at the photodetector is measured to have a smaller amplitude, since a ‘1’ to ‘0’ transition from the monitoring module output shuts down the pump lasers of the Raman amplifier at the CO. Figure 6(b) shows a detailed measurement at the ‘1’ to ‘0’ transition, indicating that the APLS response time is 1.15 ms. Considering the worst case scenario where fiber failure occurs just outside the CO, a fast APLS activation response time of less than 2 ms (~0.5 ms roundtrip propagation delay + 524 ns monitoring module response + 1.15 ms optical switch response) can be achieved.

4. Response time dependency on received optical power

As discussed in Section 1, knowledge of the monitoring module sensitivity is essential for network design and reliable network operation. In this section, we present an analytical model of the module that describes its response time probability distribution function, RTPDF(t), thus allowing its sensitivity to be evaluated. In our model, data patterning effects of the incoming monitoring signal or equivalently reflected downstream signal are not accounted for. As mentioned in Section 2, low pass filtering was deliberately introduced in the module to alleviate erroneously triggering of the decision circuit caused by patterning effects of the incoming monitoring signal. Low pass filtering in the module results in an overall bandwidth Δf that is four orders of magnitude lower than that of the downstream signal. The trade-off to low pass filtering, however, is that in the event of a fiber break, the triggering signal v(t) from the voltage limiter will cross the decision circuit threshold Vth with a slow fall time resulting in a delay in the ‘1’ to ‘0’ control signal transition. We define this delay as the response time of the monitoring module.

In the presence of noise, the Vth crossings by v(t) is statistical and varies around a mean value. The analytical model RTPDF(t) is a probability distribution function that describes these statistical transitions. The graphical representation of RTPDF(t) is illustrated in Fig. 1(c). The function RTPDF(t) is given by:
RTPDF(t)=|v(0)VthσN2|2exp(2tτ)πτ(exp(2tτ)1)32exp((v(t)VthσN2exp(tτ))22(exp(2tτ)1))
(1)
whereby parameter τ = RC = 1.551 µs is the time constant of the LPF and σN2 = 3.23 mV is the first order filtered noise variance.

The triggering signal v(t) is given by:
v(t)=[AA(1+Xexp(tτ)+Yexp(ζωnt)sinωdtωd)][G2R(i(t)×ηVTRISAT)]
(2)
where

A=2×10Popt101000×RP×RF×G1×G2
(3)
X=2τ2+τ2ωn23τ1τ(ωn2τ+3+2τ+2ζωn)
(4)
Y=(τ+2τζωn+ωn2τ+1+2ζωn+Yτ+2Xτζωn+Xτωn2)1+τ
(5)

The function v(t) was derived using the standard method of transfer functions which characterizes all cascaded components in the module, including their transient effects and nonlinear behavior. The terms inside the first square bracket on the RHS of Eq. (2) model the signal at the input of the voltage limiter whereas the terms inside the second square bracket models the voltage drop across the Shottky barrier diode used in our voltage limiter. Hence v(t) models the output of the voltage limiter, i.e. the triggering signal of the decision circuit.

Figure 7
Fig. 7 Response time PDF, RTPDF, for differing values of received optical power (Popt) at the monitoring module.
illustrates five response time distributions, each independently calculated using Eq. (1) with a different value of Popt, namely −49 dBm, −49.5 dBm, −50 dBm, −51.5 dBm, and −51.75 dBm, respectively. Low values of Popt were specifically chosen in our study to account for the high insertion loss of ER-PONs. The mean µ and jitter σ of the monitoring module’s response time are evaluated and listed in Table 1

Table 1. Response Time Mean and Jitter for Differing Received Optical Power Values

table-icon
View This Table
. The mean response time ranges from 0.16 µs to 0.7 µs, all below the 1 second and 3 second requirements. Note that the jitter values are small due to the design of the module, i.e. the combination of low pass filtering, voltage limitation, and decision circuit hysteresis. In Table 1, the calculated mean value for each Popt is compared to the experimentally measured value, showing good agreement. Both theory and experiment indicate that as Popt decreases, the mean of RTPDF occurs at an earlier time. This observation is valid since a lower Popt will result in a lower amplitude v(t). In the event of a fiber break, the falling edge of a lower amplitude v(t) will cross the fixed Vth at an earlier time. The probability of a late response beyond the 1 second and 3 second requirements was also evaluated by integrating Eq. (1) with integration limits set to 1 second and infinity, and 3 seconds and infinity, respectively. For all levels of Popt considered, the probability of a late response beyond 1 second and 3 seconds is zero. Overall, the contribution of the delay from the monitoring module is small when compared to that of the optical switch and amplifier interlock that have response times on a millisecond timescale.

Finally, even though the response time of the monitoring module is inversely proportional to Popt, it was observed that power levels below −51.5 dBm (experiment) and −51.75 dBm (theory) did not result in any ‘1’ to ‘0’ transitions. This is due to the fact that at low Popt, the amplitude of v(t) is insufficient to cross Vth, yielding zero Vth crossings. Therefore, the minimum Popt or equivalently the sensitivity of the monitoring module for reliable operation is −51.5 dBm (experiment). Such high sensitivity allows the monitoring module to be applied in topologies with an extended reach and/or split ratio beyond that of a conventional PON.

As an example, consider the architecture shown in Fig. 3. Assume a fiber attenuation of 0.2 dB/km, 1x32 splitter loss of 16.5 dB, optical switch loss of 1.5 dB, and optical filter loss of 1 dB. The total return propagation loss incurred by the monitoring signal is therefore 56 dB. Further assume a downstream signal launch power of 5 dBm, a distributed Raman gain of 6.75 dB and a monitoring module receiver sensitivity of −51.5 dBm. The power margin for the system is therefore 7.25 dB. If a power margin of 1 dB is considered to be the absolute minimum tolerable for the system, the 7.25 dB power margin allows an increase of either a split ratio to 1 × 64 (incurring an additional 6 dB round trip loss) or an increase in feeder fiber reach to 65 km (incurring additional 6 dB loss round trip loss). A further increase in reach and/or split ratio can be achieved with an even higher sensitivity monitoring module through the selection of an even lower bandwidth low pass filter.

5. Summary

Extended-reach passive optical networks are future-proofed to deliver a rich mix of conventional and bandwidth intensive services to a high number of end users. Compared to conventional PONs, ER-PONs face significant challenges in providing network reliability and in ensuring hazardous laser exposure is redirected away from the point of failure within a small timeframe. In this work, a cost-effective automatic protection switching and amplifier shutdown scheme based on low-cost, highly-sensitive, and fast-responding monitoring modules, has been proposed. The demonstration of the proposed scheme in a completely passive ER-PON and in conjunction with the monitoring module was presented. Our measurements show feeder fiber failure detection and recovery times that are well within the values specified in the IEC60825-2 standard. Further, bit-error-rate measurements indicate negligible penalty for transmission of signals on the normal as well as protection paths. An analytical model of the probability density function of the module response time was presented to study its dependency on the received optical power Popt, highlighting the existence of a lower bound on the received optical power, or equivalently, a sensitivity limit for reliable detection of fiber failures. The model is an important design tool for protection-switched ER-PONs as it not only allows the mean response time as a function of Popt and bandwidth of the module to be evaluated but also the sensitivity, which in turn influences the design of other important extended-reach network parameters such as system reach and split ratio. The current scheme can be easily extended to monitor the status of the transmitter laser, and both primary and protection paths, through placing a reciprocal monitoring module at the input of the optical switch on the primary path. Through monitoring the combination of outputs from both modules, the status of the transmitter laser, primary path as well as the protection path can be monitored.

References and links

1.

F. J. Effenberger, J.-i. Kani, and Y. Maeda, “Standardization trends and prospective views on the next generation of broadband optical access systems,” IEEE J. Sel. Areas Commun. 28(6), 773–780 (2010). [CrossRef]

2.

K. Iwatsuki and J.-i. Kani, “Applications and technical Issues of wavelength-division multiplexing passive optical networks with colorless optical network units [Invited],” J. Opt. Commun. Netw. 1(4), C17–C24 (2009). [CrossRef]

3.

E. Wong, “Passive optical networks: current and next-generation technologies,” (Invited Paper), in Proc. IEEE/OSA Opt. Fiber Communication Conference Los Angeles, California, USA, NMD1 (2011).

4.

L. Mehedy, M. Bakaul, A. Nirmalathas, and E. Skafidas, “Scalable and spectrally efficient long-reach optical access networks employing frequency interleaved directly detected optical OFDM,” J. Opt. Commun. Netw. 3(11), 881–890 (2011). [CrossRef]

5.

S.-M. Lee, S.-G. Mun, M.-H. Kim, and C.-H. Lee, “Demonstration of a long-reach DWDM-PON for consolidation of metro and access networks,” J. Lightwave Technol. 25(1), 271–276 (2007). [CrossRef]

6.

L. G. Kazovsky, S.-W. Wong, V. Gudla, P. T. Afshar, S.-H. Yen, S. Yamashita, and Y. Yan, “Challenges in next-generation optical access networks: addressing reach extension and security weaknesses,” IET Optoelectron. 5(4), 133–143 (2011). [CrossRef]

7.

E. Wong and K. L. Lee, “Automatic protection, restoration and survivability of long-reach passive optical networks,” in Proc. IEEE Int. Conference on Communication (ICC), Kyoto, Japan, paper SAC ASN-P (2011).

8.

K. L. Lee, J. L. Riding, A. V. Tran, and R. S. Tucker, “Extended-reach GPON for rural areas using distributed raman amplfiers,” in Proc. IEEE/OSA Opt. Fiber Communication Conference, San Diego, CA, NME3 (2009).

9.

T.-K. Chan, C.-K. Chan, L.-K. Chen, and F. Tong, “A self-protected architecture for wavelength-division-multiplexed passive optical networks,” IEEE Photon. Technol. Lett. 15(11), 1660–1662 (2003). [CrossRef]

10.

Y. Hsueh, W. Shaw, L. G. Kazovsky, A. Agata, and S. Yamamoto, “SUCCESS PON demonstrator: experimental exploration of next-generation optical access networks,” IEEE Commun. Mag. 43(8), S26–S33 (2005). [CrossRef]

11.

F. An, D. Gutierrez, K. S. Kim, J. W. Lee, and L. G. Kazovsky, “SUCCESS-HPON: a nextgeneration optical access architecture for smooth migration from TDM-PON to WDM-PON,” IEEE Commun. Mag. 43(11), S40–S47 (2005). [CrossRef]

12.

N. Nadarajah, E. Wong, M. Attygalle, and A. Nirmalathas, “Protection switching and local area network emulation in passive optical networks,” J. Lightwave Technol. 24(5), 1955–1967 (2006). [CrossRef]

13.

X. Cheng, Y. J. Wen, Z. Xu, Y. Wang, and Y.-K. Yeo, “Survivable WDM-PON with self-protection and in-service fault localization capabilities,” Opt. Commun. 281(18), 4606–4611 (2008). [CrossRef]

14.

H. Song, D.-M. Seol, and B.-Y. Kim, “Hardware-accelerated protection in long-reach PON”, in Proceedings of the IEEE/OSA Opt. Fiber Commun. Conf, San Diego, CA, USA, OThP7 (2009).

15.

ITU-T G.664, Optical Safety Procedures and Requirements for Optical Transport Systems, 2003, ITU.

16.

E. Wong and M. A. Summerfield, “Sensitivity evaluation of baseband carrier-sense circuit for optical CSMA/CA packet networks,” J. Lightwave Technol. 22(8), 1834–1843 (2004). [CrossRef]

17.

K. Hinton, P. Farrell, A. Zalesky, L. Andrew, and M. Zukerman, “Automatic laser shutdown implications for all optical data networks,” J. Lightwave Technol. 24(2), 674–680 (2006). [CrossRef]

18.

E. Wong and M. A. Summerfield, “Performance analysis of baseband carrier-sense circuit in optical CSMA networks,” IEEE Photon. Technol. Lett. 14(5), 708–710 (2002). [CrossRef]

OCIS Codes
(060.4370) Fiber optics and optical communications : Nonlinear optics, fibers
(060.4261) Fiber optics and optical communications : Networks, protection and restoration

ToC Category:
Fiber Optics and Optical Communications

History
Original Manuscript: February 1, 2012
Revised Manuscript: March 15, 2012
Manuscript Accepted: March 29, 2012
Published: April 3, 2012

Citation
Elaine Wong and Ka-Lun Lee, "Characterization of highly-sensitive and fast-responding monitoring module for extended-reach passive optical networks," Opt. Express 20, 9019-9030 (2012)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-20-8-9019


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References

  1. F. J. Effenberger, J.-i. Kani, and Y. Maeda, “Standardization trends and prospective views on the next generation of broadband optical access systems,” IEEE J. Sel. Areas Commun.28(6), 773–780 (2010). [CrossRef]
  2. K. Iwatsuki and J.-i. Kani, “Applications and technical Issues of wavelength-division multiplexing passive optical networks with colorless optical network units [Invited],” J. Opt. Commun. Netw.1(4), C17–C24 (2009). [CrossRef]
  3. E. Wong, “Passive optical networks: current and next-generation technologies,” (Invited Paper), in Proc. IEEE/OSA Opt. Fiber Communication Conference Los Angeles, California, USA, NMD1 (2011).
  4. L. Mehedy, M. Bakaul, A. Nirmalathas, and E. Skafidas, “Scalable and spectrally efficient long-reach optical access networks employing frequency interleaved directly detected optical OFDM,” J. Opt. Commun. Netw.3(11), 881–890 (2011). [CrossRef]
  5. S.-M. Lee, S.-G. Mun, M.-H. Kim, and C.-H. Lee, “Demonstration of a long-reach DWDM-PON for consolidation of metro and access networks,” J. Lightwave Technol.25(1), 271–276 (2007). [CrossRef]
  6. L. G. Kazovsky, S.-W. Wong, V. Gudla, P. T. Afshar, S.-H. Yen, S. Yamashita, and Y. Yan, “Challenges in next-generation optical access networks: addressing reach extension and security weaknesses,” IET Optoelectron.5(4), 133–143 (2011). [CrossRef]
  7. E. Wong and K. L. Lee, “Automatic protection, restoration and survivability of long-reach passive optical networks,” in Proc. IEEE Int. Conference on Communication (ICC), Kyoto, Japan, paper SAC ASN-P (2011).
  8. K. L. Lee, J. L. Riding, A. V. Tran, and R. S. Tucker, “Extended-reach GPON for rural areas using distributed raman amplfiers,” in Proc. IEEE/OSA Opt. Fiber Communication Conference, San Diego, CA, NME3 (2009).
  9. T.-K. Chan, C.-K. Chan, L.-K. Chen, and F. Tong, “A self-protected architecture for wavelength-division-multiplexed passive optical networks,” IEEE Photon. Technol. Lett.15(11), 1660–1662 (2003). [CrossRef]
  10. Y. Hsueh, W. Shaw, L. G. Kazovsky, A. Agata, and S. Yamamoto, “SUCCESS PON demonstrator: experimental exploration of next-generation optical access networks,” IEEE Commun. Mag.43(8), S26–S33 (2005). [CrossRef]
  11. F. An, D. Gutierrez, K. S. Kim, J. W. Lee, and L. G. Kazovsky, “SUCCESS-HPON: a nextgeneration optical access architecture for smooth migration from TDM-PON to WDM-PON,” IEEE Commun. Mag.43(11), S40–S47 (2005). [CrossRef]
  12. N. Nadarajah, E. Wong, M. Attygalle, and A. Nirmalathas, “Protection switching and local area network emulation in passive optical networks,” J. Lightwave Technol.24(5), 1955–1967 (2006). [CrossRef]
  13. X. Cheng, Y. J. Wen, Z. Xu, Y. Wang, and Y.-K. Yeo, “Survivable WDM-PON with self-protection and in-service fault localization capabilities,” Opt. Commun.281(18), 4606–4611 (2008). [CrossRef]
  14. H. Song, D.-M. Seol, and B.-Y. Kim, “Hardware-accelerated protection in long-reach PON”, in Proceedings of the IEEE/OSA Opt. Fiber Commun. Conf, San Diego, CA, USA, OThP7 (2009).
  15. ITU-T G.664, Optical Safety Procedures and Requirements for Optical Transport Systems, 2003, ITU.
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