In this thesis, we demonstrate bidirectional transmission of 6 x 2.5 Gb/s WDM signal over 320 km single mode fiber with three bidirectional amplifiers. For bidirectional add/drop of WDM signals, we propose a novel bidirectional add/drop amplifier(BADA) composed of an NxN arrayed-waveguide grating. With two propoposed BADAs, we demonstrate bidirectional add/drop transmission of wavelength interleaved 8 x 2.5 Gb/s WDM signals over 120 km single mode fiber. We estimate the scalability of bidirectional transmission system and network with the proposed BADAs.
Three bidirectional amplifiers are used for bidirectional transmission of 6 x 2.5 Gb/s WDM signals over 320 km single mode fiber. The bidirectional amplifier has 22 dB gain and 5.5 dB noise figure at -22 dBm/ch input power. We employe optical bandpass filters to suppress relative intensity noise caused by Rayleigh backscattering and optical reflection. The measured power penalties after 320 km transmission were 0 ~ -0.6 dB. The negative penalties arise from the pulse compression by the modulator chirp. The transmission distance can be extended to 560 km, when the effective reflection coefficient of optical path is -24 dB and filter suppression ratio is -35 dB.
The BADA is the essential component for bidirectional optical ring network. We propose a BADA using only one N x N arrayed-waveguide grating. The proposed BADA suppresses the relative intensity noise without optical bandpass filter by interconnecting loopback paths of arrayed-waveguide grating asymmetrically. The elimination of optical bandpass filter enables the wavelength interleaved bidirectional transmission. Thus, the channel spacing becomes two times that of the band splitted bidirectional transmission. As a result, the effects of fiber nonlinearities such as four-wave mixing (FWM) and cross phase modulation(XPM) can be reduced. With two proposed BADAs, we demonstrate wavelength interleaved bidirectional add/drop transmission of 8 x 2.5 Gb/s WDM signals over 120 km single mode fiber. The measured penalties were 0.6 ~ -0.2 dB.
We estimate the scalability of 2-fiber WDM bidirectional self-healing ring network composed of the proposed BADAs. When the effective reflection coefficient of optical path is -24 dB, we can accommodate 8 nodes with 40 km node spacing. However, extra optical filters with 14 dB extinction ratio are required to accommodate 8 nodes with 80 km node spacing.
