Analog Optical Links presents the basis for the design of analog links. Following an introductory chapter, there is a chapter devoted to the development of the small signal models for common electro-optical components used in both direct and external modulation. However this is not a device book, so the theory of their operation is discussed only insofar as it is helpful in understanding the small signal models that result. These device models are then combined to form a complete link. With these analytical tools in place, a chapter is devoted to examining in detail each of the four primary link parameters; gain, bandwidth, noise figure and dynamic range. Of particular interest is the inter-relation between device and link parameters. A final chapter explores some of the trade offs among the primary link parameters.

Analog Optical Links: Theory and Practice

A description is given of a GaAs-AlGaAs, loaded-line traveling-wave modulator which has achieved bandwidths up to 36 GHz to date with low ( >

High-speed III-V semiconductor intensity modulators

The design, fabrication and characterization of a traveling wave Ti:LiNbO/sub 3/ Mach-Zehnder interferometric modulator are discussed. The dependence of the velocity match condition on electrode thickness and wall angle is demonstrated experimentally and with finite element calculations. A set of test electrode structures is fabricated to study electrical losses in the modulator electrode. Loss coefficients are assigned to different sections of the device, and dielectric and radiative losses are shown to play an important role at high frequencies. This information is used in conjunction with finite-element calculations to develop accurate models for both the electrical and optical responses. The frequency dependence of the half-wave voltage is measured and shown to be in good agreement with a model. >

Performance and modeling of broadband LiNbO/sub 3/ traveling wave optical intensity modulators

We have developed ultrashort pulse generation by the electrooptic modulation method, where continuous-wave laser light of any wavelength can be converted to trains of ultrashort optical pulses with a variable and high repetition frequency by means of an electrooptic phase modulator for the generation of deeply chirped light, and an optical group-delay-dispersion circuit or an optical synthesizer for the compression of the chirped light. Adopting the technologies of domain inversion and guided-wave optics to this electrooptic modulation method, it will be possible to realize integrated ultrashort optical pulse generators.

Optical pulse generation by electrooptic-modulation method and its application to integrated ultrashort pulse generators

We describe the design, fabrication, and characteristics of a Ti:LiNbO/sub 3/ optical modulator with a ridge structure. The structure keeps microwave propagation loss low and enables a large interaction between microwaves and optical waves under the conditions of velocity-matching 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 75 GHz and a driving voltage of 5.0 V at a wavelength of 1.5 /spl mu/m. >

A broadband Ti:LiNbO/sub 3/ optical modulator with a ridge structure

A wideband and low-driving voltage Ti:LiNbO3 Mach-Zehnder optical modulator of nearly 50 Ω characteristic impedance has been developed employing a shielded-phasevelocity-matching travelling-wave (TW) electrode. Both wide modulation bandwidth of 20 GHz (3 dB optical) and low driving voltage of 4.7 V were attained at 1.52 μm wavelength.

New travelling-wave electrode Mach-Zehnder optical modulator with 20 GHz bandwidth and 4.7 V driving voltage at 1.52 μm wavelength

Hybrid-mode and quasi-TEM analyses are carried out for coplanar waveguide traveling-wave electrodes applicable to z-cut Ti:LiNbO3 optical modulators. The analyses are based on the spectral-domain approach. The microwave effective index and the characteristic impedance are clarified, together with the microwave conductor loss. These are incorporated to accurately predict the modulator characteristics. It is shown that these characteristics can be greatly improved by employing a thicker buffer layer. High-speed and low-driving-power Ti:LiNbO/sub 3/ optical modulators are realized at 1.52 mu m wavelength. Agreement between the calculated and measured results is good. >

Spectral-domain analysis of coplanar waveguide traveling-wave electrodes and their applications to Ti:LiNbO/sub 3/ Mach-Zehnder optical modulators

This paper presents the reliability test results for LD modules, optical couplers, and APD modules, which are fabricated through methods for achieving and assuring a high degree of reliability for use in 400-Mbit/s submarine optical fiber transmission systems. In particular, the paper presents methods for evaluating the optical component reliability as well as an investigation into the degradation factors in the coupling circuits. From the reliability test results obtained, the paper also discusses the mechanism and test acceleration of wear-out degradation following reliability tests conducted for more than 8000 h on the fabricated optical components. These optical components are consequently confirmed to be highly reliable for a system life of 25 years.

Reliability of optical components for use in submarine optical fiber transmission systems

A 20-GHz bandwidth, <5 V driving voltage at 1.53-μm wavelength improved thermal stability balanced-bridge Mach-Zehnder Interferometric switch is demonstrated.

M. Yanagibashi

Papers

New travelling-wave electrode Mach-Zehnder optical modulator with 20 GHz bandwidth and 4.7 V driving voltage at 1.52 μm wavelength

Spectral-domain analysis of coplanar waveguide traveling-wave electrodes and their applications to Ti:LiNbO/sub 3/ Mach-Zehnder optical modulators

Reliability of optical components for use in submarine optical fiber transmission systems

A Broadband, Low Driving Voltage 2 × 2 Ti:LiNbO3 Optical Switch

Broad-band and low-driving-power LiNbO3 external optical modulators