We demonstrate an extended reach 60 km coarse wavelength division multiplexing (CWDM)-time division multiple access (TDMA) passive optical network (PON) with 40 Gb/s capacity for both down and upstream directions. The system leverages existing 10 Gb/s TDMA PON technologies and incorporates various subsystems such as volume manufacturable optical transmitters, a prototype 10 Gb/s burst-mode receiver, hybrid semiconductor optical amplifier-Raman amplifiers, and a cyclic CWDM multiplexer. We confirm that this 32-user system has sufficient power margin to accommodate 128 users.

A predistortion circuit with adjustable amounts of third- and fifth-order predistortion is studied both theoretically and experimentally. The circuit is used to cancel the third- and fifth-order intermodulation distortion of a 1.55-/spl mu/m integrated electroabsorption modulator/DFB laser. The CSO obtained is -61 dBc and the CTB is reduced 22.6 dB to -65 dBc. This performance is maintained after fiber amplification and propagation through 13 km of nondispersion shifted fiber due to the modulator's low chirp. Dithering of the DFB laser's injection current is employed to increase the stimulated Brillouin scattering (SBS) threshold to +13.4 dBm.

The explosive growth in internet, multimedia and wireless traffic in recent years is rapidly exhausting capacity in public networks worldwide, forcing network service providers to aggressively install new lines and upgrade old ones. Fortunately, technological breakthroughs in the areas of erbium-doped fiber amplifiers (EDFA's), passive wavelength demultiplexers and low chirp sources have made all-optical dense wavelength-division multiplexed (WDM) systems a cost-effective way to utilize the vast bandwidth already available in the embedded fiber plant. WDM systems offer additional operational advantages, including high ultimate capacity, bit-rate transparency, flexible growth strategies, and the potential to use all-optical wavelength routing in future broadband network architectures, Commercial WDM systems operating at the OC-48 (2.5 Gbit/s) line rate are now available, and OC-192 (10 Gbit/s) terminal equipment which is under development will further enhance the capacity of these systems.One of the keys to viable WDM systems is the availability of inexpensive low-chirp optical transmitters. By taking advantage of photonic integrated circuit technology, it is possible to produce monolithically integrated DFB laser/EA modulators (EML's) with low chirp, low drive voltage and high extinction ratio, in a single compact package, In this talk we will discuss the operating characteristics of these devices and their relationship to WDM system performance.

We have transmitted 10 Gb/s data over 130 km standard fiber without any dispersion penalty in receiver sensitivity (for 10/sup -9/ BER) and with a 7% eye margin for 10/sup -15/ BER by operating an integrated EA/DFB laser with low extinction ratio (/spl epsi/=5 dB) and negative chirp (/spl Delta//spl nu/=-0.01 nm).

The performance of analogue CATV systems using narrow linewidth sources and low-chirp modulation is limited by low power-thresholds for stimulated Brillouin scattering (SBS) and excess noise from multipath interference (MPI). Using a low-chirp linearised integrated DFB laser/electroabsorption modulator as a transmitter, the authors have increased the SBS threshold by 5dB to +13.6dBm fibre launch power and suppressed MPI by dithering the laser bias current at 1.7GHz.

Transmission performance of a 10-Gb/s integrated electroabsorption modulator/DFB laser has been evaluated in terms of the eye margin degradation and the receiver sensitivity penalty caused by the chromatic dispersion in the standard (non-DSF) fiber. Combination of low extinction ratio (/spl epsi/=5 dB) and negative chirp (/spl Delta/v=-0.01 nm) operation allows 10-Gb/s transmission over 130-km standard fiber without any dispersion penalty in receiver sensitivity (for 10/sup -9/ BER) and with a 7% eye margin for 10/sup -15/ BER.

Monolithically integrated electroabsorption modulated laser grown by selective-area epitaxy using MOVPE is a very essential source for multigigabit long-haul WDM transmission systems employing EDFAs. Such an EML offers very low chirp, low drive voltage, long-term reliability and compact size.<>

We report a method for depositing clean, uniform and stable SiOx dielectric films with high control and reproducibility. The technique uses a molecular or chemical beam epitaxy system (MBE or CBE). The technique offers many advantages over the conventional methods such as load lock facility, accurate determination of the flux, low background contamination, in-situ process monitoring tools, and heating, rotation and tilting of the substrate. Rutherford backscattering (RBS) shows that the films deposited without oxygen are stoichiometric, 50% oxygen and 50% Si, irrespective of the deposition rate or temperature. Such SiO films have a resistivity of ≥1013 Ω · and a nominal refractive index of 2 at 632.8 nm. The refractive index can be reduced by introducing a controlled amount of oxygen into the chamber to result in SiOx (x = 1–2) films. The SiO films have uniform density and composition, and are free from voids, or any inclusions of different crystalline or amorphous phases. These SiO films are easy to pattern and their erosion rate is slower than that of SiO2 deposited by plasma enhanced chemical vapor deposition (PECVD). During 192 h soak in 99°C deionized (DI) water, no moisture absorption was observed in SiO films deposited at a rate of 2 Å/s. Even in films deposited at 11 Å/s, the moisture content after 192 h soak in 99°C DI water was about one third the moisture content of an as-deposited typical PECVD SiO2 film, indicating that the SiO films are highly resistant to moisture absorption and the film quality improves with reducing deposition rate. The insulating, mechanical and optical properties of SiOx films make them suitable for many applications such as surface passivation, mask for processing and facet coating of lasers. The process can be easily integrated with MBE/CBE which would greatly simplify and improve the III–V semiconductor processing. It may also be possible to deposit such dielectric films by CBE using gaseous compound sources

Optical transmitters with monolithically integrated electroabsorption-modulator/DFB lasers (EMLs) are expected to be key components in future lightwave transmission systems. The low chirp of these devices makes them well suited for long-haul (500 km) 2.5-Gbit/s transmission systems that make use of existing standard fiber and erbium-doped fiber amplifiers (EDFAs).1 Recently, several groups have also reported transmission at 10 Gbit/s over 50 km of standard fiber,2 which is the theoretical dispersion limit, as well as over longer spans by using dispersion-shifted fiber3,4 or nonlinear dispersion compensation.2 However, many of these devices have a butt-joined waveguide structure and/or use polyimide dielectrics to reduce the parasitic capacitance of the modulator,2,3 both of which are serious concerns for manufacturability and long-term reliability.

Electrical predistortion is used to linearise an integrated 1.55 /spl mu/m DFB laser/electroabsorption modulator, yielding a 77-channel CTB of -54.1 dBc and CSO of -61.3 dBc. No significant increase in distortion is measured after Er-doped fibre amplification and propagation through 13 km of non-dispersion-shifted fibre.

Low-cost highly linear analog optical sources are required for future analog amplitude-modulated cable TV (CATV) systems, which are planned at 1.55 μm to take advantage of the high powers obtainable using fiber amplifiers. The chirp produced by directly modulated lasers at this wavelength is problematic in systems employing fiber amplifiers or non-dispersion-shifted fibers [1]. Integrated electroabsorption modulated lasers (EMLs) are used increasingly as digital sources due to their low chirp [2].

One of the keys to viable WDM systems is the availability of inexpensive low-chirp optical transmitters at 1.55 μm. By taking advantage of photonic integrated circuit technology, it is possible to produce monolithically integrated DFB or DBR laser/electroabsorption modulators (EMLs) with low chirp, low drive voltage and high extinction ratio, in a single compact package. 2.5 Gbit/s EMLs have recently become commercially available, and prototype 10 Gbit/s EMLs are available for system experiments

Summary form only given. This talk reviews high speed sources for present and future communication links. We describe directly modulated DFB and Fabry-Perot lasers suitable for 2.5 and 10 GBit/s systems, together with analog links from dc to 20 GHz. Next generation integrated DFB/electro-absorption modulator devices and high performance optical pulse sources will be discussed

A device quality of selective epitaxy growth of InGaAsP/InP multiple quantum well (MQW) structure using low-pressure metalorganic vapor phase epitaxy (MOVPE) technique is described. The technique is applied to a monolithically integrated electroabsorption modulator with distributed feedback (DFB) and distributed Bragg reflector (DBR) lasers. Superior device characteristics such as efficient modulation, low threshold current and high efficiency operation of the integrated devices are obtained.