Lasers come in many shapes and sizes! For telecom purposes, DFB lasers are used quite a bit and they can be made for many colors (or in more technical jargon for different wavelengths). Most of the time, a laser has a single wavelength, but this wavelength can be different for different lasers (you just have to play with certain parameters on the physical structure of the laser). There are also lasers that are said tunable as they can achieve different color by allowing dynamic control of the said physical parameter (which is usually the cavity length, but sometimes can be the temperature of the cavity)
For telecomm purposes, lasers are often located in the THz band (in wavelength, common lasers are sitting at the 1550 nm band and 1310 nm (which correspond to wavelengths where the loss of an optical fiber is minimal)
Of course, you can get lasers working at wavelengths far from this, in the UV and far-UV region (e.g. I work almost daily with a laser operating at 244 nm), there are some in the visible spectrum (which is about 400-750 nm). And those I mentioned in the 1310 nm and 1550 nm region are obviously in the IR (infrared) region of the spectrum.
Yeah, the article is not clear on that detail, but I am aware of the record you are talking about. Nevertheless, 2.56 Tbps is nothing too impressive nowadays if it is using WDM.
No, the speed of electronics limits the overall transmision rate on an optical channel. But, scientists know that optical fibers have a very wide available bandwidth. How can we exploit it, even though the electronics are slow? We use different colors of light. Each color sends a signal of, let's say, 40 Gbps, and electronic components can deal with that. If we have hundreds of different light colors going into a single fiber, we multiply the bit rate and the transmission capacity is increased significantly. But, at both the transmitter and the receiver, we must have hundreds of electronic components for all the different colors. So why would we want to do this? Well, installing fibers or electrical cables is extremely expensive so we want to maximise the capacity of each cable or optical fiber. (for example, think about transoceanic cables!) We rather have many electronic components at the transmit and receive side than install new fibers! It is a cost issue at this point.
Unless this is meant as a joke and I am not getting it, your comment doesn't make much sense in the context of optical networks. Currently, optical networks are dumb pipes that are used in a point-to-point fashion. In other words, they send your data, regardless of what it is. It is protocol transparent, so you can send whatever traffic you want. It can be encrypted, numerically encoded in any way that you like, that's the job of the electronic components. When dealing with optical networks, we assume that the electronic components can handle their work load. This is the main reason why we use many wavelengths to achieve such high wavelengths. Each wavelength can send slower traffic rates, but the overall rate of the optical link is the sum of the rates of each individual wavelength. For example, assume that you have 3 lasers of different colors: blue, green and red. Laser blue sends info at 40 Gbps on the optical fiber (any type of data, previously encrypted or not). Laser green and red send data at the same rate. At the receiver, we select each color individually and recover the signal carried by that "light color", i.e. the wavelength. Each laser may be sending 40 Gbps, but the overall transmission capacity of the fiber was increased to 120 Gbps by using different "colors".
Optical fiber gives you a loss of approx a quarter dB per km (0.25 dB/km) - which is very close to the theoretical limit of current glass optical fibers. At 160 km, that gives you an attenuation in your optical signal of about 40 dB. All-optical amplifiers - EDFAs - (without signal regeneration, just plain amplification) can give you a good boost in power and you can cascade many before the signal becomes too distorted (because each amplifier amplifies both the noise and the signal). An other type of all-optical amplifier - DRAs - give you a lesser gain, but they do not amplify the noise (pretty cool concept!), so a combination of EDFAs and DRAs can get you an all-optical link - without regenerators - of several thousands of kms!
Research scientists do work in a modular fashion. One research group works on one aspect of a problem and other groups work on other aspects. In this case, if one span of optical fiber (without amplifiers) can handle very high bit rates, it is not too difficult to extend this to ultra long haul (UHL) networks which have many spans of optical fibers with all-optical amplifiers - provided that you have amplifiers available for the band of wavelengths that you are using. I am guessing that this is a limitation to this experiment, but a lot of research is done by other groups on all-optical amplifiers working in different wavelength bands. One group cannot do it all, but they rather concentrate on one area and let other groups develop the other areas.
So this is indeed a pretty cool and impressive result if we understand the experiment and can see its implication for future optical networks!
Research scientists are always ahead of the "real world". This has always been, always will be. You can view their work as creating ideas, innovations and technologies. Once these ideas have been published, it is the industry's work to pick them up and transform them into something commercially usable. Yes, there is a lot of research projects that can be viewed as useless, but, you should see it as a brainstorming of new technologies. Not all will end up in something revolutionary, but it may incite new ideas and/or bring new products or ways of doing things in the "real world".
If we want to be technical, OC refers to a SONET rate transmitted on a single wavelength... and this record is using wavelength division multiplexing (WDM) to achieve this kind of transmission rate. So they could be using any type of OC they want and many wavelengths. I am figuring they must be using OC-768 or at very best, OC-3072. Don't forget that the speed of electronics is the limiting factor here!
They really should create a category of story called "Tin-foiled hat". The logo for this category would be quite interesting I'm sure;) This story and many past ones would be perfect to fall into this category!!;)
Light years represent a distance.... not a time value:P I guess the poster wanted to say something like trillions of kilometers per light (distance/c = 1000m / (3*10^8 m/s) = 3.33 microseconds).. hehe I just found light years a funny idea as to comparing the technological advancements betw. the companies...:P
Sorry, but you missed the point. It's not the transfer that they want to secure, it's the sharing they want to eliminate. By keeping track of the origin of a file, well... it's a good way to start a lawsuit against that mp3 sharer.
And since the RIAA wants to start selling MP3's as well, they don't want everyone to share them. Thus, they want a security that it will not be freely distributed. The new Super-MP3 allows this.
What part of "don't exploit poorer people" don't you understand?? You're implying quite a lot of things here. I never mentionned stopping trading, I only stated that coercion and quasi-slavery is not considered as moral thing in my point of view. Yes, we can still employ third world inhabitants. Yes, they can thus keep their jobs and make their economy bloom. But No we shouldn't pay them so little that even in their society where the cost of life is lower that ours, they struggle to make it through another day. And I could go on, but I'll stop. I hope you get the point.
Your values are clearly short sighted and narrow. Depriving people in India of jobs just because you feel Americans are somehow "entitled" to them does not place any value on the "human condition".
Talk about missing my point... Read the post parent to mine and tell me if it limited only to software and IT jobs. I felt that there was more implied than just this. And what makes you feel that I am an american? Even more, I don't even work in IT... But sure, I "feel Americans are somehow "entitled" to IT jobs". Yeah, Sure.
Geez... some people did miss my point... Quoting from the grandparent post, If the cost/benefit of the product is the same then it doesn't matter if it's made in New York USA, Newcastle UK, Nalanda India, or Nanjing China.
Support companies that make products that are worth buying at prices that are worth paying - wherever they are made.
I don't think that this post was limited to software products and IT jobs. But if MY interpretation was wrong, then sorry.
Geez... Americans... What makes you think that I am one? But if you look well enough, you should be able to find a few companies which are better than others. May not be perfect, but still better...
Don't shut them down, just don't make sweat shops. Create acceptable working conditions. Sure, we'll have to pay more for products, but being able to fully furnish a house at a 99 cents store is pushing things a bit too far.
But yeah, I must admit that it must be hard to conceive that people are busting their butt off for months straight without any vacation, living on a "campus" (which costs them half their paycheck as living expenses by the "nice" company employing them) only to get enough money to go live back (and poorly, that is) with their immediate families for may be a week or two. Yeah, it must be hard to imagine this, especially since you are probably sitting comfy in your ergonomic la-Z-boy chair surrounded with junk you don't need.
So, according to your point of view, exploiting third world countries inhabitants, running sweat shops, etc are both legitimate and moral decisions by companies?
And say that you were modded Insightful... Well, you can continue to shop at WalMart, but you won't see me there... Even if their prices are better. My values with respect to the human condition are obviously quite different than yours and some moderators...
So, what's needed is a way to make simple homework problems interesting, so that the student sticks with it. That's a nearly impossible task.
Even though I agree it may be a difficult task, I don't agree with your statement in general. Math and any other school subject can be made quite interesting by presenting real life applications. It is a good source of motivation to know that you would know how to solve certain "real-life" problems. Also, I think that putting a few theories presented in class is also another good way to motivate students. Instead of only studying one theory/subject at a time, they are then able to see the link between the theories, thus putting the pieces of the puzzle together. I believe this to be another approach to get students to do their homeworks and actually understand what they are doing...
Slashdot Mirror
Sorry dude, you missed the sarcasm of the GP...
and they've patented it.
Thank you Dr. Obvious... That was the joke. Good for you, you got it right! ;)
Lasers come in many shapes and sizes! For telecom purposes, DFB lasers are used quite a bit and they can be made for many colors (or in more technical jargon for different wavelengths). Most of the time, a laser has a single wavelength, but this wavelength can be different for different lasers (you just have to play with certain parameters on the physical structure of the laser). There are also lasers that are said tunable as they can achieve different color by allowing dynamic control of the said physical parameter (which is usually the cavity length, but sometimes can be the temperature of the cavity)
For telecomm purposes, lasers are often located in the THz band (in wavelength, common lasers are sitting at the 1550 nm band and 1310 nm (which correspond to wavelengths where the loss of an optical fiber is minimal)
Of course, you can get lasers working at wavelengths far from this, in the UV and far-UV region (e.g. I work almost daily with a laser operating at 244 nm), there are some in the visible spectrum (which is about 400-750 nm). And those I mentioned in the 1310 nm and 1550 nm region are obviously in the IR (infrared) region of the spectrum.
Hope this helps!
Yeah, the article is not clear on that detail, but I am aware of the record you are talking about. Nevertheless, 2.56 Tbps is nothing too impressive nowadays if it is using WDM.
No, the speed of electronics limits the overall transmision rate on an optical channel. But, scientists know that optical fibers have a very wide available bandwidth. How can we exploit it, even though the electronics are slow? We use different colors of light. Each color sends a signal of, let's say, 40 Gbps, and electronic components can deal with that. If we have hundreds of different light colors going into a single fiber, we multiply the bit rate and the transmission capacity is increased significantly. But, at both the transmitter and the receiver, we must have hundreds of electronic components for all the different colors. So why would we want to do this? Well, installing fibers or electrical cables is extremely expensive so we want to maximise the capacity of each cable or optical fiber. (for example, think about transoceanic cables!) We rather have many electronic components at the transmit and receive side than install new fibers! It is a cost issue at this point.
Unless this is meant as a joke and I am not getting it, your comment doesn't make much sense in the context of optical networks. Currently, optical networks are dumb pipes that are used in a point-to-point fashion. In other words, they send your data, regardless of what it is. It is protocol transparent, so you can send whatever traffic you want. It can be encrypted, numerically encoded in any way that you like, that's the job of the electronic components. When dealing with optical networks, we assume that the electronic components can handle their work load. This is the main reason why we use many wavelengths to achieve such high wavelengths. Each wavelength can send slower traffic rates, but the overall rate of the optical link is the sum of the rates of each individual wavelength. For example, assume that you have 3 lasers of different colors: blue, green and red. Laser blue sends info at 40 Gbps on the optical fiber (any type of data, previously encrypted or not). Laser green and red send data at the same rate. At the receiver, we select each color individually and recover the signal carried by that "light color", i.e. the wavelength. Each laser may be sending 40 Gbps, but the overall transmission capacity of the fiber was increased to 120 Gbps by using different "colors".
Optical fiber gives you a loss of approx a quarter dB per km (0.25 dB/km) - which is very close to the theoretical limit of current glass optical fibers. At 160 km, that gives you an attenuation in your optical signal of about 40 dB. All-optical amplifiers - EDFAs - (without signal regeneration, just plain amplification) can give you a good boost in power and you can cascade many before the signal becomes too distorted (because each amplifier amplifies both the noise and the signal). An other type of all-optical amplifier - DRAs - give you a lesser gain, but they do not amplify the noise (pretty cool concept!), so a combination of EDFAs and DRAs can get you an all-optical link - without regenerators - of several thousands of kms! Research scientists do work in a modular fashion. One research group works on one aspect of a problem and other groups work on other aspects. In this case, if one span of optical fiber (without amplifiers) can handle very high bit rates, it is not too difficult to extend this to ultra long haul (UHL) networks which have many spans of optical fibers with all-optical amplifiers - provided that you have amplifiers available for the band of wavelengths that you are using. I am guessing that this is a limitation to this experiment, but a lot of research is done by other groups on all-optical amplifiers working in different wavelength bands. One group cannot do it all, but they rather concentrate on one area and let other groups develop the other areas. So this is indeed a pretty cool and impressive result if we understand the experiment and can see its implication for future optical networks!
You forgot that the rate is in Tbps TeraBITS per seconds... not bytes... so there is an 8 factor to take into consideration there!
Research scientists are always ahead of the "real world". This has always been, always will be. You can view their work as creating ideas, innovations and technologies. Once these ideas have been published, it is the industry's work to pick them up and transform them into something commercially usable. Yes, there is a lot of research projects that can be viewed as useless, but, you should see it as a brainstorming of new technologies. Not all will end up in something revolutionary, but it may incite new ideas and/or bring new products or ways of doing things in the "real world".
If we want to be technical, OC refers to a SONET rate transmitted on a single wavelength... and this record is using wavelength division multiplexing (WDM) to achieve this kind of transmission rate. So they could be using any type of OC they want and many wavelengths. I am figuring they must be using OC-768 or at very best, OC-3072. Don't forget that the speed of electronics is the limiting factor here!
Have you been following the Darwin Awards?
They really should create a category of story called "Tin-foiled hat". The logo for this category would be quite interesting I'm sure ;) This story and many past ones would be perfect to fall into this category!! ;)
Light years represent a distance.... not a time value :P I guess the poster wanted to say something like trillions of kilometers per light (distance/c = 1000m / (3*10^8 m/s) = 3.33 microseconds).. hehe I just found light years a funny idea as to comparing the technological advancements betw. the companies... :P
Steve Jobs is there as well as many more. sorry to be a joy buster but they didn't forget about Gates ;)
I don't have any thoughts, you insensitive clod!!! (wait, this isn't a poll... oh well)
And since the RIAA wants to start selling MP3's as well, they don't want everyone to share them. Thus, they want a security that it will not be freely distributed. The new Super-MP3 allows this.
What part of "don't exploit poorer people" don't you understand?? You're implying quite a lot of things here. I never mentionned stopping trading, I only stated that coercion and quasi-slavery is not considered as moral thing in my point of view. Yes, we can still employ third world inhabitants. Yes, they can thus keep their jobs and make their economy bloom. But No we shouldn't pay them so little that even in their society where the cost of life is lower that ours, they struggle to make it through another day. And I could go on, but I'll stop. I hope you get the point.
Talk about missing my point... Read the post parent to mine and tell me if it limited only to software and IT jobs. I felt that there was more implied than just this. And what makes you feel that I am an american? Even more, I don't even work in IT... But sure, I "feel Americans are somehow "entitled" to IT jobs". Yeah, Sure.
I don't think that this post was limited to software products and IT jobs. But if MY interpretation was wrong, then sorry.
Geez... Americans... What makes you think that I am one? But if you look well enough, you should be able to find a few companies which are better than others. May not be perfect, but still better...
But yeah, I must admit that it must be hard to conceive that people are busting their butt off for months straight without any vacation, living on a "campus" (which costs them half their paycheck as living expenses by the "nice" company employing them) only to get enough money to go live back (and poorly, that is) with their immediate families for may be a week or two. Yeah, it must be hard to imagine this, especially since you are probably sitting comfy in your ergonomic la-Z-boy chair surrounded with junk you don't need.
And say that you were modded Insightful... Well, you can continue to shop at WalMart, but you won't see me there... Even if their prices are better. My values with respect to the human condition are obviously quite different than yours and some moderators...
Even though I agree it may be a difficult task, I don't agree with your statement in general. Math and any other school subject can be made quite interesting by presenting real life applications. It is a good source of motivation to know that you would know how to solve certain "real-life" problems. Also, I think that putting a few theories presented in class is also another good way to motivate students. Instead of only studying one theory/subject at a time, they are then able to see the link between the theories, thus putting the pieces of the puzzle together. I believe this to be another approach to get students to do their homeworks and actually understand what they are doing...
What makes you think I am a US citizen??