Erbium-doped fiber amplifiers are modeled using the propagation and rate equations of a homogeneous two-level laser medium. Numerical methods are used to analyze the effects of optical modes and erbium confinement on amplifier performance, and to calculate both the gain and amplified spontaneous emission (ASE) spectra. Fibers with confined erbium doping are completely characterized from easily measured parameters: the ratio of the linear ion density to fluorescence lifetime, and the absorption of gain spectra. Analytical techniques then allow accurate evaluation of gain, saturation, and noise in low-gain amplifiers (G >

Modeling erbium-doped fiber amplifiers

https://engineering.purdue.edu/~fsoptics/articles/Ultrafast_optical_pulse_shaping_tutorial-Weiner.pdf

Ultrafast optical pulse shaping: A tutorial review

We introduce a traffic model for circuit switched all-optical networks (AONs) which we then use to calculate the blocking probability along a path for networks with and without wavelength changers. We investigate the effects of path length, switch size, and interference length (the expected number of hops shared by two sessions which share at least one hop) on blocking probability and the ability of wavelength changers to improve performance. Our model correctly predicts unobvious qualitative behavior demonstrated in simulations by other authors.

Models of blocking probability in all-optical networks with and without wavelength changers

Feature Issue on
Optical Access Networks (OAN) The passive optical network (PON) is
an optical fiber based network architecture, which can provide much higher bandwidth
in the access network compared to traditional copper-based networks. Incorporating
wavelength-division multiplexing (WDM) in a PON allows one to support much higher
bandwidth compared to the standard PON, which operates in the "single-wavelength
mode" where one wavelength is used for upstream transmission and a separate one is
used for downstream transmission. We present a comprehensive review of various
aspects of WDM-PONs proposed in the literature. This includes enabling device
technologies for WDM-PONs and network architectures, as well as the corresponding
protocols and services that may be deployed on a WDM-PON. The WDM-PON will become a
revolutionary and scalable broadband access technology that will provide high
bandwidth to end users.

/pdf/wavelength-division-multiplexed-passive-optical-network-wdm-428jyy569l.pdf

Wavelength-division-multiplexed passive optical network (WDM-PON) technologies for broadband access: a review (Invited)

The main bandwidth bottleneck in today's networks is in the access segment. To address that bottleneck, broadband fiber access technologies such as passive optical networks (PONs) are an indispensable solution. The industry has selected time-division multiplexing (TDM) for current PON deployments. To satisfy future bandwidth demands, however, next-generation PON systems are being investigated to provide even higher performance. In this paper, we first review current TDM-PONs; we designate them as generation C. Next, we review next-generation PON systems, which we categorize into C+1 and C+2 generations. We expect C+1 systems to provide economic near-term bandwidth upgrade by overlaying new services on current TDM-PONs. For the long term, C+2 systems will provide more dramatic system improvement using wavelength division multiplexing technologies. Some C+2 architectures require new infrastructures and/or equipment, whereas others employ a more evolutionary approach. We also review key enabling components and technologies for C+1 and C+2 generations and point out important topics for future research.

/pdf/next-generation-optical-access-networks-41pmztcn8d.pdf

Next-Generation Optical Access Networks

This paper presents an optical carrier supply module (OCSM) that functions as a common multicarrier light source, a wavelength bank, for superdense wavelength-division multiplexing (SD-WDM) networks that utilize a large number of wavelengths with narrow channel spacing. A novel sideband generator based on a sinusoidal amplitude-phase hybrid modulation scheme is the key technique. The sideband generator generates nine flattened optical sidebands within 3 dB from one seed light source, and the input from wavelength-division multiplexing (WDM) seed carriers expands the number of generated sidebands. Scalability against the number of wavelengths is achieved by increasing the number of seed carriers used. The SD-WDM system employing OCSM reduces the number of laser diodes (LDs) and attendant wavelength monitoring/stabilization circuits. Multiple distributions to SD-WDM networks by splitting the OCSM output can promote this effect. We designed OCSM and experimentally investigated its performance pertaining to the electrical signal-to-noise ratio (SNR) of the OCSM output. The experimental results show the wavelength scalability to 1000 channels. We also developed an OCSM prototype that generated 12.5-GHz-spaced 256-channel WDM carriers. All the generated carriers exhibit the electrical SNR of more than 31.5 dB at 2.5 Gb/s and the power flatness of within 3 dB. The distribution over 100 SD-WDM networks is experimentally confirmed.

Optical carrier supply module using flattened optical multicarrier generation based on sinusoidal amplitude and phase hybrid modulation

A narrow linewidth of 1.4 kHz with single frequency operation is demonstrated in an Er-doped fibre ring-laser. A stable lasing spectrum can be achieved using a single polarisation fibre-cavity. An optical bandpass filter incorporated in the ring-cavity makes the lasing wavelength tunable, and a 2.8 nm tuning range is demonstrated.

Wavelength-tunable single-frequency and single-polarisation Er-doped fibre ring-laser with 1.4 kHz linewidth

This paper investigates the impact of backreflection lights on upstream transmission in wavelength division multiplexing (WDM) single-fiber loopback access networks, where a WDM light source is located at the central office (CO) and each optical network unit (ONU) includes an optical modulator with optical amplifiers. This study considers backreflection lights from two sources, the continuous wave (CW) light at the CO (Reflection-I) and the modulated signal at the ONU (Reflection-II). It is confirmed, for the first time, that the impact of Reflection-II increases strongly with ONU gain. To estimate the impact of these backreflection lights, a simple intensity noise estimation scheme is presented. This scheme clarifies that the acceptable transmission line losses is 10 dB for 1.25 Gb/s under the optical return loss (ORL) of -32 dB.

Impact of backreflection on upstream transmission in WDM single-fiber loopback access networks

This paper describes the technical issues of access and metro networks based on wavelength division multiplexing (WDM) technologies, some solutions, and an experimental demonstration. A WDM star access network with colorless optical network units (ONUs) is proposed. For realizing the colorless ONU, two approaches are introduced; optical carrier supply and spectrum slicing. In addition, a WDM metro ring network with scalable optical add/drop multiplexers (OADMs), namely the tapped-type OADM, is proposed to effectively accommodate the large amount of traffic issued from access networks. Prototypes are constructed and used to verify the feasibility of the proposed WDM technologies.

Access and metro networks based on WDM technologies

This article proposes and demonstrates a WDM-based access network that directly connects end users over a wide area to the center node and provides guaranteed full-duplex Gigabit Ethernet access services to each of over 100 users. The center node employs an optical carrier supply module that generates not only the optical carriers for the downstream signals but also those for the upstream signals. The latter are supplied to optical network units (ONUs) at users' homes/buildings via the network. Since the ONUs simply modulate the optical carriers supplied from the center node via the network, they are wavelength-independent.

Katsumi Iwatsuki

Papers

Optical carrier supply module using flattened optical multicarrier generation based on sinusoidal amplitude and phase hybrid modulation

Wavelength-tunable single-frequency and single-polarisation Er-doped fibre ring-laser with 1.4 kHz linewidth

Impact of backreflection on upstream transmission in WDM single-fiber loopback access networks

Access and metro networks based on WDM technologies

A WDM-based optical access network for wide-area gigabit access services