Robert E. Tench

2.488 Gb/s-318 km repeaterless transmission using erbium-doped fiber amplifiers in a direct-detection system

The authors have achieved a 2.488 Gb/s, 318 km repeaterless transmission without any fiber dispersion penalty through a nondispersion-shifted fiber in a direct detection system. The system was loss limited with a T-R power budget of 57 dB. Three key components enabled the authors to achieve this result: (1) a Ti:LiNbO/sub 3/ external amplitude modulator enabling a dispersion-free transmission, (2) erbium-doped fiber amplifiers increasing the transmitting power to +16 dBm, and (3) an erbium-doped fiber preamplifier enabling a high-receiver sensitivity of -4.1 dBm for 10/sup -9/ BER. To the authors knowledge, this result is the longest repeaterless transmission span length ever reported for direct detection at this bit rate. From the experimental results and a theoretical model, the authors identified the sources of the receiver sensitivity degradation from the quantum limit (-48.6 dBm) and estimated the practically achievable receiver sensitivity of approximately -44 dBm ( approximately -124 photons/bit) for 2.5 Gb/s optical preamplifier detection.<<ETX>>

A high capacity noncoherent FSK lightwave field experiment using Er/sup 3+/-doped fiber optical amplifiers

A description is given of high-bit-rate fiber-optic noncoherent frequency-shift keying (FSK) transmission field experiments using Er/sup 3+/-doped optical amplifiers. Transmission distances of 70 km for a four-channel 6.8-Gb/s capacity experiment and 177 km for single-channel 1.7-Gb/s transmissions were demonstrated in a typical field environment. Measurements of receiver sensitivity dispersion penalty, interchannel crosstalk, and long-term bit-error-rate performance are presented. Results show negligible degradations due to >3000-ps/nm dispersion and interchannel crosstalk, in addition to stable long-term performance. This performance demonstrates the applicability of noncoherent FSK and fiber amplifier technologies.<<ETX>>

1.55 mu m, 2.5 Gb/s direct detection repeaterless transmission of 160 km nondispersion shifted fiber

A repeaterless transmission experiment through 160 km of non-dispersion-shifted fiber at bit rate of 2.5 Gb/s is reported. A direct-current-modulated distributed-feedback laser in conjunction with an erbium-doped fiber amplifier for power amplification constitute the transmitter. The regenerator includes the conventional APD photodetector and the subsequent amplifiers and timing recovery circuit. With careful decision level and laser bias adjustment, less than 0.6 dB of overall system degradation is incurred in this simple system configuration.<<ETX>>

Field measurements of 10-Gb/s line-rate transmission on the Columbus-IIB submarine lightwave system

We report field measurements of virtually error-free transmission at 10 Gb/s line rate on the installed Columbus-IIB optically amplified submarine lightwave system. For 2100-km transmission an average experimental Q-factor of 18.8 dB was achieved. An eye margin (EM) of +80 mV at 10/sup -15/ bit-error-ratio (BER) was also measured. For 4200 km transmission the average experimental Q-factor was 16.0 dB. Implications for system operation at 10 Gb/s line rate are discussed.<<ETX>>

1.7 Gb/s-419 km transmission experiment using a shelf-mounted FSK coherent system and packaged fiber amplifier modules

Experiments to assess the commercial viability of long-span FSK coherent systems with fiber amplifiers were performed. Transmission spans of 253, 365, and 419 km with integrated shelf-mounted modules have been demonstrated in repeaterless systems and in single-fiber and two-fiber amplifier repeatered systems, respectively.<<ETX>>

5W 1950nm Brillouin-free efficient single clad TDFA

We report the performance of a two stage single clad (SC) Thulium-doped fiber amplifier (TDFA), delivering an output power of 5 W at 1952 nm without stimulated Brillouin scattering (SBS) for a single-frequency input signal. A slope efficiency greater than 60 %, a signal gain greater than 60 dB and an input dynamic range > 30 dB are achieved. The amplifier topology was optimized with a modelization tool of the SC TDFA performance: experimental results and simulations are in good agreement.

Multistage single clad 2 micron TDFA with a shared L-band pump source

We report the experimental performance and simulation of a multiwatt two-stage TDFA using an L-band (1567 nm) shared pump source. We focus on the behavior of the amplifier for the parameters of output power Pout, gain G, noise figure NF, signal wavelength λs, and dynamic range. We measure the spectral performance of the TDFA for three specific wavelengths (λs= 1909, 1952, and 2004 nm) chosen to cover the low-, mid-, and upper-wavelength operating regions of the wideband amplifier. We also compare the performance of the two-stage shared pump TDFA with a one stage shared pump amplifier. Experimental results are in good agreement with simulation.

20-W 1952-nm tandem hybrid single and double clad TDFA

A simple engineering design is important for achieving high Thulium-doped amplifier (TDFA) performance such as good power conversion, low noise figure (NF), scalable output power, high gain, and stable operation over a large dynamic range. In this paper we report the design, performance, and simulation of two stage high-power 1952 nm hybrid single and double clad TDFAs. The first stage of our hybrid amplifier is a single clad design, and the second stage is a double clad design. We demonstrate TDFAs with an output power greater than 20 W with single-frequency narrow linewidth (i.e. MHz) input signals at both 1952 and 2004 nm. An optical 10 dB bandwidth of 80 nm is derived from the ASE spectrum. The power stage is constructed with 10 μm core active fibers showing a maximum optical slope efficiency greater than 50 %. The experimental results lead to a 1 dB agreement with our simulation tool developed for single clad and double clad TDFAs. Overall this hybrid amplifier offers versatile features with the potential of much higher output power.