Redefining electrical current law with the transistor laser

UNIVERSITY OF ILLINOIS ^ | May 12, 2010 | Liz Ahlberg

[decimon]

CHAMPAIGN, Ill. — While the laws of physics weren’t made to be broken, sometimes they need revision. A major current law has been rewritten thanks to the three-port transistor laser, developed by Milton Feng and Nick Holonyak Jr. at the University of Illinois.

With the transistor laser, researchers can explore the behavior of photons, electrons and semiconductors. The device could shape the future of high-speed signal processing, integrated circuits, optical communications, supercomputing and other applications. However, harnessing these capabilities hinges on a clear understanding of the physics of the device, and data the transistor laser generated did not fit neatly within established circuit laws governing electrical currents.

“We were puzzled,” said Feng, the Holonyak Chair Professor of Electrical and Computer Engineering. “How did that work? Is it violating Kirchhoff’s law? How can the law accommodate a further output signal, a photon or optical signal?”

[clamper1797]

PIE in the sky ?

[Matchett-PI]

bttt

[thinkin out loud]

Very simplistic title ( not your fault) and article. The writer misses the point entirley. This is NOT an earth shaking OMG everything that went before is wrong moment.

This merely allows those in the electrical field to do what those in the thermodynamics field have been doing from day one. you have energy of various types. It must be conserved. What does that look like? The ‘new’ equations merely add the concept of optical output to the already evaluated charge output

[decimon]

Light work ping.

[who_would_fardels_bear]

And what about the tachyons?

They may have to go back and revise their work ... and with tachyons ... they will be.

[thinkin out loud]

you forgot your sarcasm symbol....

optical output is measurable tachyons are imaginary....

[pfflier]

The way I read it the process still conforms to Kirchoff’s law (current in = sum of current from each load out). It’s the law of conservation of energy that is in question. Apparently, with the photons and electrons as output there appears to be more energy out than in.

[spunkets]

No pie in the sky. That Kirchoff law represented conservation of charge as currents entering and leaving a junction. This law is simply conservation of energy entering ad leaving a junction. There's nothing novel about applying the law of conservation of energy to any process, including the laser transistor system they've engineered.

That system itself works by boosting the V in the conductor with the electric field of the laser beam. At the point where the beam enters the conductor, the E field is increased and the current jumps correspondingly. That jump in current doesn't represent creation of charge though, as would be the case in circuits w/o external fields applied.

Before the junction: E = i*V*t = q*V = q*E_{before_junction}*v_charge

After the junction:

E = i*V*t + c*ε_o*E² = q*E_{before_junction}*v_charge + c*ε_o*E²;

The laser just increases the charge velocity at the junction.

[spunkets]

"The way I read it the process still conforms to Kirchoff’s law (current in = sum of current from each load out). "

See #9. The conservation law applies to the charge, not current, becuase the current increases at the junction, because of the application of the external field. Since the current out does not equal the current in for this device, consesrvation of energy needs to be used. The charge carriers in this device are being accelerated at the junction. That is why the currents aren't equal.

[Bean Counter]

[SunkenCiv]

Thanks decimon!

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[spunkets]

Not ε_o. It should be the dielectric constant of the material, ε_material.

[neverdem]

Thanks SC

[rmlew]

Tachyons are a theoretic expanation for otherwise inexplicable anomalies. I’d explain this I tuned out after Einstien. Quantum theory and String Theory make my head hurt.

[grey_whiskers]

Thanks for the summary, you rock.

Cheers!