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Kazuto NOGUCHI Hiroshi MIYAZAWA Osamu MITOMI
This paper describes the design, fabrication, and performance of a novel Ti:LiNbO3 optical modulator with a two-stage coplanar waveguide electrode for 40 Gbit/s optical transmission systems. The structure consists of a thin lower electrode and a thick upper electrode in conjunction with a ridge structure. The lower electrode ensures low voltage and the upper layer provides good microwave characteristics. Based on simulation results, a fully-packaged module was fabricated. The measured 3-dB electrical bandwidth is 30 GHz with a half-wave voltage of 2. 9 V.
This paper describes the scalability of a full-mesh wavelength division multiplexing star-structure network based on an arrayed-waveguide grating router (AWG-STAR). The scalability of the network is examined experimentally. A power penalty of 0.1dB is obtained with a 32-node network and an estimated scalability of up to 100 nodes is confirmed.
Kazuto NOGUCHI Osamu MITOMI Hiroshi MIYAZAWA
We describe the design, fabrication, and characteristics of a push-pull type ridged Ti:LiNbO3 optical modulator with two electrodes. The structure keeps microwave propagation loss low and enables a large interaction between microwaves and optical waves under the condition of velocity and impedance matching, resulting in a large modulation bandwidth and low driving voltage. Using this structure, we have developed an optical intensity modulator with an optical 3-dB bandwidth of 45 GHz (an electrical 3-dB bandwidth of 30 GHz) and a half-wave voltage of 3.9 V in single-electdoe operation (a half-wave voltage of 1.95 V in push-pull operation)at a wavelength of 1.55µm.
An oblique-polishing tilted-coupling method for LD's and waveguides is proposed for suppressing feedback light from the endfaces. It is confirmed that the instability of coherence in DFB-LD is reduced with little excess loss.