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I would like to find out if a dual-parallel Mach-Zehnder modulator with either 1) fixed optical path lengths or 2) variable optical path lengths commensurate with today's announcement by a team of American researchers at Stanford University which has experimented with an emerging memory technology that could offer switching times on the order of 1 picosecond,

can mix or single sideband modulate with equal conversion efficiency or gain a pure red , green or blue visible light laser input signal with a broadband optical source.

[Frank's EDIT August 7 2016 6:00 A.M. One way to do this is create an array of 3 independent Mach-Zenhder modulators each centered at either red , green or blue laser light wavelength or frequency whose outputs are fed into a 4 port optical circulator. In the future, we anticipate that the laser pointer threat to large commercial planes will become multi-frequency so that an array of 3 independent Mach-Zenhder modulators coupled with an 4 port optical circulator could be potentially powerful way to combat this threat. I got this idea from Dr. Shawn Teller Ph.D at ThorLabs yesterday.]

The reason I ask this question is we want to design a reconfigurable band-rejection notch filter for red , green or blue visible light laser input signals which does not change the refraction index or optical path length electro-mechanically.

Here is an alternative way to solve this problem using picosecond tuning speeds which are sufficient to protect pilots of the existing 25,000 large Airbus and Boeing passenge planes from exposure to visible laser ray irradiation from less than 100 yards away

Experiments point toward memory chips 1,000 times faster than today's devices SAN FRANCISCO, Aug. 8 (Xinhua)-- A team of American researchers at Stanford University has experimented with an emerging memory technology that could store data permanently while allowing certain computer operations to occur up to 1,000 times faster than today's memory devices.

The 19-member team, led by Aaron Lindenberg, an associate professor of materials science and engineering at Stanford University and of photon science at the SLAC National Accelerator Laboratory, has worked on a new class of semiconductor materials and the result suggest that the new approach may be more energy efficient.

"This work is fundamental but promising," said Lindenberg. "A thousandfold increase in speed coupled with lower energy use suggests a path toward future memory technologies that could far outperform anything previously demonstrated."

While memory chips today are based on silicon technologies that switch electron flows on and off, representing the ones and zeroes that drive digital software, one possible next-generation technology is based on phase-change materials that can exist in two different atomic structures, each of which has a different electronic state. A crystalline, or ordered, atomic structure, permits the flow of electrons, while an amorphous, or disordered, structure inhibits electron flows.

By applying short bursts of heat, supplied electrically or optically, the structural and electronic states of these materials -- changing their phase from one to zero and back again. They retain whichever electronic state conforms to their structure. Once their atoms flip or flop to form a one or a zero, the material stores that data until another energy jolt causes it to change.

The new research, detailed in Physical Review Letters, focused on the unimaginably brief interval when an amorphous structure began to switch to crystalline, when a digital zero became a digital one. The intermediate phase -- where the charge flows through the amorphous structure like in a crystal -- is known as "amorphous on."

In the presence of a sophisticated detection system, the Stanford researchers jolted a small sample of amorphous material with an electrical field comparable in strength to a lightning strike. Their instrumentation detected that the amorphous-on state -- initiating the flip from zero to one -- occurred less than a picosecond after they applied the jolt.

Showing that phase-change materials can be transformed from zero to one by a picosecond excitation suggests that this emerging technology could store data many times faster than silicon computer RAM for tasks that require memory and processors to work together to perform computations.

In addition, the researchers said the electrical field that triggered the phase change was of such a brief duration that it points toward a storage process that could become more efficient than today's silicon-based technologies. While much work remains to turn this discovery into functioning memory systems, attaining such speed using a low-energy switching technique suggests that phase-change technology has the potential to revolutionize data storage.

"A new technology which demonstrate a thousandfold advantage over incumbent technologies is compelling," Lindenberg said. "I think we've shown that phase change deserves further attention."

[EDIT August 9 5:19 A.M. Frank , My question is which of the two alternatives is better, Stanford Professor Aaron Lindenberg's 1 picosecond excitation or an array of 3 uncoupled Mach-Zenhder modulators each centered at either red , green or blue laser light wavelength or frequency whose outputs are fed into a 4 port optical circulator to prevent back reflection and control noise.

Please correct any physics mistakes I may have made.

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  • $\begingroup$ Please think carefully about the difference between an optical circulator and an optical combiner. $\endgroup$ – Frank Aug 7 '16 at 13:49
  • $\begingroup$ The Stanford University researchers focused their efforts on developing a purely electronic model of of threshold switching. Their ultrafast electronic switch requires repetitive excitation with single cycle THz pulses of a few picoseconds duration and very high electric field strength, 480 kilovolt per centimeter which is different than the operating environment in commercial aviation. $\endgroup$ – Frank Aug 11 '16 at 5:26
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The Stanford University team of researchers focused their efforts on developing a purely electronic model of of threshold switching. Their ultrafast electronic switch requires repetitive excitation with single cycle THz pulses of a few picoseconds duration and very high electric field strength, 480 kilovolt per centimeter because the electric field required for threshold switching increases as pulse duration become shorter.

As a result, such a hypothetical tunable band-reject filter installed in the cockpit window cavity is not suitable for commercial aviation because repetitive pulsed excitation and 480 kilovolt per cm electric field amplitudes would wreak havoc with commercial avionics and navigation systems in the aircraft.

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