The paper presents monolithic fiber-optic CPA systems - where the mode-locked oscillator, pulse stretcher, pulse shaper, pulse picker, and all amplifier stages are comprised of fusion spliced fiber devices - emitting up to 300 μJ compressed pulse output with duration <;500 fs (FWHM). This is a 6 times higher pulse energy than previously reported for monolithic fiber femtosecond lasers. Higher femtosecond pulse energy enables cutting and drilling through thicker materials, at faster rates, without imposing a heat affected zone (HAZ). Generating this femtosecond beam with a monolithic fiber-optic system provides the most compact and stable form factor, suitable for industrial work cell integration and global factory deployment.

We describe femtosecond laser systems optimized for high value applications in precision industrial micro-machining. Unprecedented system performance and reliability are enabled by novel fiber-optic architectures and integrated autonomous software control systems.

Heating a photo-darkened ytterbium fiber causes a recovery in spectral transmission to the pre-darkened state. Exposure to H2 at high temperatures causes a permanent change in the visible transmission identical to that caused by photo-darkening.

Distributed Raman amplification in the transmission fiber is an important technology for advancing the system performance. Co-directionally pumped Raman amplifiers can enhance the performance and allow more flexibility in the system design. However, several sources of non-amplified spontaneous emission noise need to be carefully considered in the amplifier design. The intrinsic cross gain modulation associated with the transient nature of Raman effect can impair the system performance, if the amplifier is not properly designed. We have isolated and measured the impairment due to cross gain modulation in 200-km bi-directionally pumped fiber spans. The penalty depends on the fiber dispersion characteristics and can be small for up to 20 dB on-off co-gain. The benefit of co-directionally pumped Raman amplifiers can be used in multiple long-span transmission to compensate the high loss while maintaining a low nonlinear impairment. It can also be used to extend the length of a single span and achieve a simple system configuration for unrepeatered applications. As opposed to using a span containing multiple fiber types and remotely pumped erbium-doped fiber amplification to achieve transmission over spans with > 60 dB loss, we have demonstrated an unrepeatered link over a single type of fiber with bi-directional Raman pumping. Using the simple conventional non-return-to-zero data format, we achieved transmission of 20 × 10Gb/s channels over a 300-km span of non-zero dispersion-shifted fiber. This simple system configuration provides an important option for terrestrial transmission in remote areas where service access is difficult.

We have demonstrated the unrepeatered transmission of 20×10.66Gbit/s over 300km non-zero dispersion-shifted fiber with conventional NRZ modulation format by using bi-directionally pumped Raman amplification, as opposed to hybrid fiber types or remotely pumped EDF.

The following patents owned by Lucent Technologies were issued by the U.S. Patent and Trademark Office from July through September 2003. Lucent was also the recipient of 166 non-U.S. patents during the same period.

Fiber-based devices like EDFA and DCMs are critical building blocks of communications systems. In several new areas, novel fibers enable new properties and advances in photonic components. Areas like amplification, dispersion control, nonlinear devices and microstructured fiber will be discussed.

A silica optical fiber doped with Sb is fabricated with a refractive-index profile that is comparable with standard single-mode fiber. In D(2)-loaded samples, we observe UV photosensitivity with an initial refractive-index-modulation growth rate six times higher than that of the equivalent Ge-doped standard fibers. Enhanced temperature stability of the Bragg grating strength up to 200 degrees C is also observed. Grating growth kinetics in the Sb-doped fiber is compared with those of other Ge-doped photosensitive fibers.

High power lasers and amplifiers for communication networks based on cladding pump fiber operate at unprecedented power levels. The high power and unique structure of cladding pump fiber present new challenges to the optical reliability of lasers and amplifiers based on these novel fibers. In this paper we present results on the reliability of cladding pump fiber under high power both in the multimode pump waveguide and in the rare earth doped core

We propose and demonstrate a cascaded distribution fabric for WDM Passive Optical Networks (WDM-PON) that delivers distinct data to potentially tens of thousands of subscribers using a single, centralized WDM source. This is possible by assigning a unique time slot to each wavelength, and replicating this ‘bit-interleaved’ WDM signal in cascaded stages of amplification and power splitting, before data is encoded for each WDM-PON by a single TDM modulator.

We define two new figures of merit and use them to compare the best optical performance expected from ideal Er-doped fluoride fibre amplifiers (EDFFAs) and silica-based Er-doped fibre amplifiers (EDFAs). We use a computer model with measured spectral gain and loss parameters. It assumes homogeneous broadening and includes all known loss mechanisms

A high-power Er-Yb fiber amplifier for WDM applications has been constructed using a matched mid-stage gain shaping filter, Using precise measurements and careful design considerations, excellent gain flatness, with less than 0.2-dB variation, was obtained over a 14-nm spectral bandwidth, By simply adjusting the pump power to the amplifier, it was possible to maintain the flattened amplifier gain shape over a wide input signal power range from -11 dBm to 1 dBm, A low external noise figure of 5.2 dB at 1-dBm signal input and a high-output power up to 24.6 dBm has been measured.

An Er-Yb fibre amplifier has been constructed with dispersion compensation and gain tilt correction. Gain tilt has been minimised within 0.2 dB/nm for the spectral width of 11 nm and input power range of 0-4 dBm. A noise figure of 5 dB and output power of 21 dBm has been obtained for this operating range. Tests using a 77 channel NTSC signal show its compatibility to CATV applications.

PROBLEM TO BE SOLVED: To improve stability to a temperature change by specifying the effective refractive index of the clad layer of the core of an optical fiber and a speed change with respect to the temperature, thereby forming a long period grating formed with the core having the perturbations of the refractive index. SOLUTION: The core 11 of the optical fiber 10 has a plurality of perturbations 15 of the refractive index arranged at periodic intervals, by which the long period grating 14 of a central wavelength λp is formed. The clad layer 12 enclosing the core 11 has the effective refractive index smaller than the effective refractive index of a core waveguide mode and the average change rate with respect to the temp. has the value sufficiently approximate to the average change rate with respect to the temp. of the core 11. Further, the change rate with respect to the temp. of the central wavelength λp is specified to <=4nm/100 deg.C. The clad layer is preferably a composite clad layer consisting of a first part 12 adjacent to the core 11 and having the refractive index lower than the refractive index of the core 11 and the second part 13 adjacent to the first part 12 and having the refractive index higher than the refractive index of the first part 12.

A compact and integrable diode-pumped, linear configuration fibre laser is presented. An intracavity diode serves as a pump source at 0.98 mu m as well as a Fabry-Perot etalon at 1.53 mu m. The threshold pump power of this compound cavity laser is 6 mW and the slope efficiency is 3.2%.<>

The generation of amplified spontaneous emission (ASE) in erbium-doped fiber amplifiers is characterized. A theoretical model leading to closed-form analytical expressions for the backward and forward ASE power spectra is developed for the unsaturated gain regime. The results are found to be in close agreement with the measured experimental data. Such closed-form expressions are useful to model ASE noise in low-gain, distributed fiber amplifiers.

Erbium-doped fiber amplifiers (EDFA) are now recognized as essential components for 1.5 μm optical fiber communications. An important characteristic of EDFAs is the amplified spontaneous emission (ASE), which provides useful information on its lasing characteristics. Some system applications require low-gain, distributed amplifiers for which characterization of unsaturated ASE noise features is useful.

1.2 ps transform-limited pulses at 1557 nm have been produced by passively mode locking an Er-doped fibre laser. An InGaAs/GaAs-on-GaAs superlattice was used as a fast saturable absorber. The all-fibre laser is designed to be in a ring configuration. The low pump power requirement allowed pumping by a semiconductor laser diode.<>

Dynamic compensation of low-frequency gain fluctuations in saturated erbium-doped fiber amplifiers is demonstrated. This compensation, based on a simple feedback-loop scheme makes it possible to reduce transient gain fluctuations efficiently across the whole amplifier bandwidth using only a low-power optical feedback signal. Such an, automatic gain control technique could be applied to suppress data packet interference due to traffic bursts in multiple-access networks, as well as in the implementation of long-haul fiber systems using erbium fiber amplifiers.< >

A two-level model of the erbium-doped fiber-amplifier is used to analyze the dependence of the amplifier gain saturation, saturated output power, and excess noise factor on pump and signal wavelengths.