F. C. Garcia Gunning

Demonstration of amplified data transmission at 2 µm in a low-loss wide bandwidth hollow core photonic bandgap fiber

The first demonstration of a hollow core photonic bandgap fiber (HC-PBGF) suitable for high-rate data transmission in the 2 µm waveband is presented. The fiber has a record low loss for this wavelength region (4.5 dB/km at 1980 nm) and a >150 nm wide surface-mode-free transmission window at the center of the bandgap. Detailed analysis of the optical modes and their propagation along the fiber, carried out using a time-of-flight technique in conjunction with spatially and spectrally resolved (S2) imaging, provides clear evidence that the HC-PBGF can be operated as quasi-single mode even though it supports up to four mode groups. Through the use of a custom built Thulium doped fiber amplifier with gain bandwidth closely matched to the fibers low loss window, error-free 8 Gbit/s transmission in an optically amplified data channel at 2008 nm over 290 m of 19 cell HC-PBGF is reported.

The turbo-switch - a novel technique to increase the high-speed response of SOAs for wavelength conversion

A new scheme for wavelength conversion employing two semiconductor optical amplifiers (SOAs) results in substantially higher speed and reduced data-patterning effects. Error-free conversion at 170.4 Gbit/s is demonstrated.

100 Gbit/s WDM transmission at 2 µm: transmission studies in both low-loss hollow core photonic bandgap fiber and solid core fiber

We show for the first time 100 Gbit/s total capacity at 2 µm waveband, using 4 × 9.3 Gbit/s 4-ASK Fast-OFDM direct modulation and 4 × 15.7 Gbit/s NRZ-OOK external modulation, spanning a 36.3 nm wide wavelength range. WDM transmission was successfully demonstrated over 1.15 km of low-loss hollow core photonic bandgap fiber (HC-PBGF) and over 1 km of solid core fiber (SCF). We conclude that the OSNR penalty associated with the SCF is minimal, while a ~1-2 dB penalty was observed after the HC-PBGF probably due to mode coupling to higher-order modes.

InP-Based Active and Passive Components for Communication Systems at 2 μm

Progress on advanced active and passive photonic components that are required for high-speed optical communications over hollow-core photonic bandgap fiber at wavelengths around 2 μm is described in this paper. Single-frequency lasers capable of operating at 10 Gb/s and covering a wide spectral range are realized. A comparison is made between waveguide and surface normal photodiodes with the latter showing good sensitivity up to 15 Gb/s. Passive waveguides, 90° optical hybrids, and arrayed waveguide grating with 100-GHz channel spacing are demonstrated on a large spot-size waveguide platform. Finally, a strong electro-optic effect using the quantum confined Stark effect in strain-balanced multiple quantum wells is demonstrated and used in a Mach-Zehnder modulator capable of operating at 10 Gb/s.

Towards a Practical Implementation of Coherent WDM: Analytical, Numerical, and Experimental Studies

Future optical networks will require the implementation of very high capacity (and therefore spectral efficient) technologies. Multi-carrier systems, such as Orthogonal Frequency Division Multiplexing (OFDM) and Coherent WDM (CoWDM), are promising candidates. In this paper, we present analytical, numerical, and experimental investigations of the impact of the relative phases between optical subcarriers of CoWDM systems, as well as the effect that the number of independently modulated subcarriers can have on the performance. We numerically demonstrate a five-subcarrier and three-subcarrier 10-GBd CoWDM system with direct detected amplitude shift keying (ASK) and differentially/coherently detected (D) phase shift keying (PSK). The simulation results are compared with experimental measurements of a 32-Gbit/s DPSK CoWDM system in two configurations. The first configuration was a practical 3-modulator array where all three subcarriers were independently modulated, the second configuration being a traditional 2-modulator odd/even configuration, where only odd and even subcarriers were independently modulated. Simulation and experimental results both indicate that the independent modulation implementation has a greater dependency on the relative phases between subcarriers, with a stronger penalty for the center subcarrier than the odd/even modulation scheme.

Expressions for the nonlinear transmission performance of multi-mode optical fiber

We develop an analytical theory which allows us to identify the information spectral density limits of multimode optical fiber transmission systems. Our approach takes into account the Kerr-effect induced interactions of the propagating spatial modes and derives closed-form expressions for the spectral density of the corresponding nonlinear distortion. Experimental characterization results have confirmed the accuracy of the proposed models. Application of our theory in different FMF transmission scenarios has predicted a ~10% variation in total system throughput due to changes associated with inter-mode nonlinear interactions, in agreement with an observed 3dB increase in nonlinear noise power spectral density for a graded index four LP mode fiber.

Single- and multi-carrier techniques to build up Tb/s per channel transmission systems

In this paper, we review emerging technologies to build up Tb/s per channel transmission capacity. The different approaches, mainly based on various implementations of orthogonal frequency division multiplexing, Nyquist wavelength division multiplexing and optical time division multiplexing, are introduced and compared with respect to complexity, spectral efficiency and transmission reach. In addition to this analysis, we review recent Tb/s per channel transmission experiments, which have employed at least one of these techniques, and compare them to conventional WDM systems.

81Gb/s WDM transmission at 2µm over 1.15km of low-loss hollow core photonic bandgap fiber

This paper presents WDM transmission at 2μm over 1.15km of HC-PBGF with wavelength channels selected to span a 36.3nm waveband. A total capacity of 81Gbit/s was achieved using 4×12.5Gbit/s NRZ-OOK external modulation and 4×7.7Gbit/s 4-ASK Fast-OFDM direct modulation signals.

WDM transmission at 2µm over low-loss Hollow Core Photonic Bandgap Fiber

Worlds first demonstration of WDM transmission in a HC-PBGF at the predicted low loss region of 2μm is presented. A total capacity of 16 Gbit/s is achieved using 1×8.5 Gbit/s and 3×2.5 Gbit/s channels modulated using NRZ OOK over 290 meters of hollow core fiber.

Recent developments in 40 Gsymbol/s coherent WDM

In this paper we investigate the non-linear transmission performance of 40 Gsymbol/s multi-carrier techniques, specifically Coherent WDM (CoWDM) for a variety of existing dispersion maps. Whilst the simulations on this paper were performed using NRZ OOK CoWDM implementation, the conclusions are also applicable to other multi-carrier techniques, such as OFDM.