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IX. Read the following statements and say whether they are true or false . Correct the false ones.

1. Vendors are attempting to combine the best of two worlds and offer gallium arsenide.

2. Combining silicon and optics is a difficult problem.

3. As some components are already available, silicon optics has been widely and reliably used commercially.

4. In waveguides silicon is used as a passive element for turning on and off the electrical current.

5. Photodetectors convert signals only from optical to electronic.

6. Direct bandgap semiconductors such as silicon used in optics are efficient at emitting light, while indirect bandgap semiconductors such as gallium arsenide are not.

7. Researchers are looking for other ways to provide silicon optics.

X. Arrange the facts given in the text on degrees of importance.

XI. Make an outline of the text.

XII. Make a short summary of the text in written form using your outline.

Part B

I. Study the key words and word combinations of the following text. Guess the topical question of it.

To be used, near feature, to replace, to improve, lucrative market, instead of, to be faster, development, cost-effective, silicon-optical components, equipment, research, extensive studies.

II. Look through the text and note the title which conveys the contents most of all.

1. Optical Systems

2. Using Silicon Optics

3. Basic Optical Components

III. Divide the text into logical parts. In each part find a key sentence.

IV. Read the outline, define if it fully reflects the contents of the text.

1. Communications among components

2. Replacing components in optical systems

3. LANs

4. Silicon optical components

5. On-chip communications

Text B

Proponents see four primary ways in which silicon optics could be used in the near future.

Silicon-optical components could replace existing transceivers in 1- and 10-Gbit Ethernet LANs. Because LANs typically include many nodes with many connections, the use of silicon optics could improve overall communications enough to justify the expense.

Equipment vendors are interested in building silicon optics for LANs in part because many corporations use these networks and thus represent a lucrative market.

While microprocessors have gotten faster, overall computer-performance increases have been limited because of slower communications via data buses and along copper wiring between chips and circuit boards.

Using optical communications instead of electrical wiring would be faster, and silicon optics could keep the implementation affordable.

Silicon-optical interconnects could replace copper wiring on chips. A single chip would contain most of the basic optical components except for the light source.

Short, high-density interconnects should be left in copper wiring because the necessary optical components would be too large and require too much power.

Research into on-chip silicon optics is ongoing. Prototype waveguides and detectors for optical interconnects are available. However, the necessary extensive studies of reliability and development of cost-effective manufacturing methods have not been done.

Intel’s approach introduces photons onto a chip via a laser. It then uses transistor-like devices to remove the buildup of electrons that the light source creates. If not removed, the electron cloud would absorb light and interfere with the generation of the continuous laser beam that is necessary for proper modulation and data transmission.

Intel expects to have silicon lasers ready for commercial use by the end of this decade.

In addition, researchers have only icon lasers. Manufacturers have had trouble beaming lasers onto a chip without causing heat, alignment, and other problems.

In addition to replacing components in silicon-based systems to make them faster, silicon optics can also replace traditional optical components in optical systems to make them more affordable.

For example, Kotura is using silicon optics to make arrays of variable optical attenuators (VOAs¹), which incrementally adjust the power of the signal passing through an optical system.

Using silicon makes the manufacturing process less expensive and improves the VOAs' performance.

Manufacturers such as Intel are also using silicon optics to make modulators for optical systems.

Note:

¹VOAs – variable optical attenuators – регулируемые оптические аттенюаторы