Re: [SI-LIST] : Interesting theoretical questions

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From: Vinu Arumugham (vinu@cisco.com)
Date: Mon Nov 01 1999 - 18:00:04 PST


subas wrote:

> Hi all,
>
> I have some theoretical questions regarding high frequency signals:
>
> 1) What is the maximum frequency you can generate electronically by our
> current technology (GaAs???)? Can we have an oscillator that can oscillate
> in the frequency of the visible light, for example?
>

LEDs!?

>
> 2) The way light gets reflected from a metal (silver in a mirror) is that it
> first induces current (as a receiving antenna) and again radiates (as a
> transmitting antenna) the EM wave instantly so that we get the impression
> that the light is being reflected by the metal surface. Then how come
> different metals can have different colors (gold - yellow) when we expect
> them all to reflect light of all colors?
>

The "free" electrons (not bound to one atom) in a metal absorb and re-radiate (reflect) light. If a wide range of energy levels are available to the electrons in a metal then it will absorb and re-radiate most wavelengths. If
there are fewer available energy levels, only some wavelengths will be reflected.

>
> 3) Has there been any computer made without any clocks (asynchronous)? How
> fast is this computer?
>

Versions of the ARM microprocessor? I believe some of Intel's parallel computers use communication devices that are self-timed. In this case, more than speed, it was to avoid distributing a clock and thus make the system more
scalable.

>
> 4) Why is optical computing getting no where? Is this because lasers are
> expensive? Or because of the lack of fast optical switch ( any non-linear
> optical device)?
>
> Thank you very much.
>
> Subas
>
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