Optical Networks - Revision history

Cmditradmin: /* Technological Applications Of The Pockels Effect */

2011-11-08T17:26:18Z

Technological Applications Of The Pockels Effect

← Older revision		Revision as of 10:26, 8 November 2011
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	=== Technological Applications Of The Pockels Effect ===		=== Technological Applications Of The Pockels Effect ===
	Light traveling through an ~~electrooptic~~ material can be phase-of-polarization modulated by refractive index changes induced by an applied electric field.		Light traveling through an electro-optic material can be phase-of-polarization modulated by refractive index changes induced by an applied electric field.

	Devices exploiting this effect include optical switches, modulators, and wavelength filters.		Devices exploiting this effect include optical switches, modulators, and wavelength filters.
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	[[Image:Gate drain modulator.png\|thumb\|200px\|A gate signal modulates the transmitted signal]]		[[Image:Gate drain modulator.png\|thumb\|200px\|A gate signal modulates the transmitted signal]]

	The timescale for electronic polarization is ~~femptoseconds~~ (vibrational polarization requires picoseconds). This fast switching increases the bandwidth (bits per second) possible for optical communication. Today people are happy with 40 gigabits per second but this won't last for long. Lithium niobate (LiNbO<sub>3</sub>) will eventually run out of speed from a purely physical standpoint. Electronic polarization of organic materials hold the promise of greatly increasing speed.		The timescale for electronic polarization is femtoseconds (vibrational polarization requires picoseconds). This fast switching increases the bandwidth (bits per second) possible for optical communication. Today people are happy with 40 gigabits per second but this won't last for long. Lithium niobate (LiNbO<sub>3</sub>) will eventually run out of speed from a purely physical standpoint. Electronic polarization of organic materials hold the promise of greatly increasing speed.

	The EO effect can be used to transduce electrical signals into optical signals. Electrical information appears as an amplitude modulation on the optical transmission. The modulator works for analog or digital data.		The EO effect can be used to transduce electrical signals into optical signals. Electrical information appears as an amplitude modulation on the optical transmission. The modulator works for analog or digital data.
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	*L = 3 cm		*L = 3 cm

	It is desirable to have a low drive voltage because there is dissipation of power creating heat which is a problem when when there are many modulators in a small space. In order to keep the V<sub>π</sub> low try to use materials that have a high r<sub>33</sub> and a high refractive index. Use knowledge of donors and acceptors, and the structure of molecules to first optimize the molecules and then the materials for electro optical activity.		It is desirable to have a low drive voltage because there is dissipation of power creating heat which is a problem when when there are many modulators in a small space. In order to keep the V<sub>π</sub> low try to use materials that have a high r<sub>33</sub> and a high refractive index. Use knowledge of donors and acceptors, and the structure of molecules to first optimize the molecules and then the materials for electro-optical activity.

	=== Waveguides ===		=== Waveguides ===

Cmditradmin: /* Ring resonator */

2010-12-16T23:17:46Z

Ring resonator

← Older revision		Revision as of 16:17, 16 December 2010
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	The electrooptical effect can be used to encode electrical information about a given color while it is in the ring.		The electrooptical effect can be used to encode electrical information about a given color while it is in the ring.

	<div id="Flash">Ring Resonator Simulation</div> <swf width="~~700~~" height="~~400~~">images/5/5f/Ringresdynamic.swf</swf>		<div id="Flash">Ring Resonator Simulation</div> <swf width="720" height="480">images/5/5f/Ringresdynamic.swf</swf>

	=== Reconfigurable Optical Add Drop Multiplexer ===		=== Reconfigurable Optical Add Drop Multiplexer ===

Cmditradmin: /* Ring resonator */

2010-12-16T22:29:20Z

Ring resonator

← Older revision		Revision as of 15:29, 16 December 2010
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	The electrooptical effect can be used to encode electrical information about a given color while it is in the ring.		The electrooptical effect can be used to encode electrical information about a given color while it is in the ring.

	<div id="Flash">Ring Resonator Simulation</div> <swf width="~~500~~" height="400">images/5/5f/Ringresdynamic.swf</swf>		<div id="Flash">Ring Resonator Simulation</div> <swf width="700" height="400">images/5/5f/Ringresdynamic.swf</swf>

	=== Reconfigurable Optical Add Drop Multiplexer ===		=== Reconfigurable Optical Add Drop Multiplexer ===

Cmditradmin: /* Ring resonator */

2010-12-16T22:29:07Z

Ring resonator

← Older revision		Revision as of 15:29, 16 December 2010
Line 202:		Line 202:
	The electrooptical effect can be used to encode electrical information about a given color while it is in the ring.		The electrooptical effect can be used to encode electrical information about a given color while it is in the ring.

	<div id="Flash">Ring Resonator Simulation</div> <swf width="500" height="400">/images/5/5f/Ringresdynamic.swf</swf>		<div id="Flash">Ring Resonator Simulation</div> <swf width="500" height="400">images/5/5f/Ringresdynamic.swf</swf>

	=== Reconfigurable Optical Add Drop Multiplexer ===		=== Reconfigurable Optical Add Drop Multiplexer ===

Cmditradmin: /* Ring resonator */

2010-12-16T22:28:52Z

Ring resonator

← Older revision		Revision as of 15:28, 16 December 2010
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	In telecommunications this is the dominant technique for increasing density of throughput in optical systems. Information can be distributed over different wavelengths; 10 wavelengths can carry 10 times as much information.		In telecommunications this is the dominant technique for increasing density of throughput in optical systems. Information can be distributed over different wavelengths; 10 wavelengths can carry 10 times as much information.
	The electrooptical effect can be used to encode electrical information about a given color while it is in the ring.		The electrooptical effect can be used to encode electrical information about a given color while it is in the ring.

			<div id="Flash">Ring Resonator Simulation</div> <swf width="500" height="400">/images/5/5f/Ringresdynamic.swf</swf>

	=== Reconfigurable Optical Add Drop Multiplexer ===		=== Reconfigurable Optical Add Drop Multiplexer ===

Cmditradmin: /* Ring resonator */

2010-11-29T19:12:39Z

Ring resonator

← Older revision		Revision as of 12:12, 29 November 2010
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	[[Image:Resonator_ring.jpg\|thumb\|300px\|]]		[[Image:Resonator_ring.jpg\|thumb\|300px\|]]
	A resonator is a device that acts a filter in an optical circuit using constructive interference.		A resonator is a device that acts a filter in an optical circuit using constructive interference.
	A ring resonator will only propagate certain wavelengths of light determined by the circumference of the ring and by the index of refraction of the material. ~~If you apply a~~ voltage to the EO material ~~you~~ will change its index of refraction, an thereby ~~you can~~ control the wavelength of light that is coupled into the ring. A ring ~~gives you the capability of building~~ a welding switch that can couple certain ~~wavelength~~ of light over to another waveguide. So we can electronically control the transfer of light from one waveguide to another. ~~You can electronically~~ control the color of light that is coupled~~, this is known as wavelength division multiplexing~~.		A ring resonator will only propagate certain wavelengths of light determined by the circumference of the ring and by the index of refraction of the material. A voltage applied to the EO material will change its index of refraction, an thereby control the wavelength of light that is coupled into the ring. A ring can be used to build a welding switch that can couple certain wavelengths of light over to another waveguide. So we can electronically control the transfer of light from one waveguide to another. Wavelength division multiplexing is the electronic control the color of light that is coupled.

	In telecommunications this is the dominant technique for increasing density of throughput in optical systems. ~~You~~ can ~~distribute information~~ over different wavelengths~~. If you have~~ 10 wavelengths ~~you~~ can carry 10 times as much information.		In telecommunications this is the dominant technique for increasing density of throughput in optical systems. Information can be distributed over different wavelengths; 10 wavelengths can carry 10 times as much information.
	~~You~~ can ~~also~~ encode electrical information about a given color while it is in the ring ~~because of the electrooptical effect~~.		The electrooptical effect can be used to encode electrical information about a given color while it is in the ring.

	=== Reconfigurable Optical Add Drop Multiplexer ===		=== Reconfigurable Optical Add Drop Multiplexer ===

Cmditradmin: /* Optical waveguides */

2010-11-29T19:06:04Z

Optical waveguides

← Older revision		Revision as of 12:06, 29 November 2010
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	[[Image:Wgthickness_modes.png\|thumb\|300px\|]]		[[Image:Wgthickness_modes.png\|thumb\|300px\|]]

	The graph show contours of beta at various thicknesses. The larger the waveguide the more modes that are possible. Multiple modes will spread out due to the differences in the speed of propagation of the waves. Therefore the majority of all long distance optical network (over 1km distance) uses single mode fiber which is very small (<2 ~~mum~~)		The graph show contours of beta at various thicknesses. The larger the waveguide the more modes that are possible. Multiple modes will spread out due to the differences in the speed of propagation of the waves. Therefore the majority of all long distance optical network (over 1km distance) uses single mode fiber which is very small (<2 μm)

	<br clear='all'>		<br clear='all'>

	=== Ring resonator ===		=== Ring resonator ===
	[[Image:Resonator_ring.jpg\|thumb\|300px\|]]		[[Image:Resonator_ring.jpg\|thumb\|300px\|]]

Cmditradmin: /* Waveguides */

2010-11-29T19:04:52Z

Waveguides

← Older revision		Revision as of 12:04, 29 November 2010
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	<br clear='all'>		<br clear='all'>
	[[Image:Si_waveguide_edensity.jpg\|thumb\|300px\|A silicon on insulator waveguide carries the light within the guide. In a slotted guide the light is concentrated between the silicon guides.]]		[[Image:Si_waveguide_edensity.jpg\|thumb\|300px\|A silicon on insulator waveguide carries the light within the guide. In a slotted guide the light is concentrated between the silicon guides.]]
	In a normal optical fiber the light intensity is concentrated in the middle of the guide. But ~~if you cut~~ a 70nm slot down the middle of the waveguide the light intensity is maximized inside the slot with tremendous amplification.		In a normal optical fiber the light intensity is concentrated in the middle of the guide. But with a 70nm slot down the middle of the waveguide the light intensity is maximized inside the slot with tremendous amplification.
	<br clear='all'>		<br clear='all'>
	[[Image:Si_waveguide_em.jpg\|thumb\|300px\|EO polymers can be placed in the slots so the light can be modulated.]]		[[Image:Si_waveguide_em.jpg\|thumb\|300px\|EO polymers can be placed in the slots so the light can be modulated.]]

Cmditradmin: /* Technological Applications Of The Pockels Effect */

2010-11-29T19:02:39Z

Technological Applications Of The Pockels Effect

← Older revision		Revision as of 12:02, 29 November 2010
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	=== Technological Applications Of The Pockels Effect ===		=== Technological Applications Of The Pockels Effect ===
	~~<swf width="500" height="400">http://depts.washington.edu/cmditr/media/mz.swf</swf>~~
	This is a Mach-Zehnder modulator which is a common device to transduce and electrical signal (yellow) into an optical signal (purple). By applying an electrical signal to one arm of the beam splitter you change the index of refraction, slow light down and then alter the constructive/destructive interference of the light waves as they recombine. Thus electricity is used to change the amplitude of the optical signal.

	Light traveling through an electrooptic material can be phase-of-polarization modulated by refractive index changes induced by an applied electric field.		Light traveling through an electrooptic material can be phase-of-polarization modulated by refractive index changes induced by an applied electric field.

	Devices exploiting this effect include optical switches, modulators, and wavelength filters.		Devices exploiting this effect include optical switches, modulators, and wavelength filters.

			<swf width="500" height="400">http://depts.washington.edu/cmditr/media/mz.swf</swf>
			This is a Mach-Zehnder modulator which is a common device to transduce and electrical signal (yellow) into an optical signal (purple). By applying an electrical signal to one arm of the beam splitter you change the index of refraction, slow light down and then alter the constructive/destructive interference of the light waves as they recombine. Thus electricity is used to change the amplitude of the optical signal.

	[[Image:Dualmz packaged.png\|thumb\|300px\|The MZ device has optical inputs and outputs (top) and electrical inputs]]		[[Image:Dualmz packaged.png\|thumb\|300px\|The MZ device has optical inputs and outputs (top) and electrical inputs]]
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	*L = 3 cm		*L = 3 cm

	It is desirable to have a low drive voltage because there is dissipation of power creating heat which is a problem when ~~you have~~ many modulators in a small space. In order to keep the V<sub>π</sub> low try to use materials that have a high r<sub>33</sub> and a high refractive index. ~~You will be able to use~~ knowledge of donors and acceptors, and the structure of molecules to first optimize the molecules and then the materials for electro optical activity.		It is desirable to have a low drive voltage because there is dissipation of power creating heat which is a problem when when there are many modulators in a small space. In order to keep the V<sub>π</sub> low try to use materials that have a high r<sub>33</sub> and a high refractive index. Use knowledge of donors and acceptors, and the structure of molecules to first optimize the molecules and then the materials for electro optical activity.

	=== Waveguides ===		=== Waveguides ===

Cmditradmin: /* Technological Applications Of The Pockels Effect */

2010-11-29T19:00:43Z

Technological Applications Of The Pockels Effect

← Older revision		Revision as of 12:00, 29 November 2010
Line 120:		Line 120:
	This is a Mach-Zehnder modulator which is a common device to transduce and electrical signal (yellow) into an optical signal (purple). By applying an electrical signal to one arm of the beam splitter you change the index of refraction, slow light down and then alter the constructive/destructive interference of the light waves as they recombine. Thus electricity is used to change the amplitude of the optical signal.		This is a Mach-Zehnder modulator which is a common device to transduce and electrical signal (yellow) into an optical signal (purple). By applying an electrical signal to one arm of the beam splitter you change the index of refraction, slow light down and then alter the constructive/destructive interference of the light waves as they recombine. Thus electricity is used to change the amplitude of the optical signal.

			Light traveling through an electrooptic material can be phase-of-polarization modulated by refractive index changes induced by an applied electric field.
	Light traveling through an electrooptic material can be phase of polarization modulated by refractive index changes induced by an applied electric field.

	Devices exploiting this effect include optical switches, modulators, and wavelength filters.		Devices exploiting this effect include optical switches, modulators, and wavelength filters.