[Laser] Laser comm and ARRL?

[Art]

Jame's reply is interesting and is cause for consideration.

At 08:26 PM 2/18/04, you wrote:
>I agree with Art, KY1K, that the ARRL rule that prohibits the use of LEDs for
>a light frequency contact seems unfair.  The frequency (color) of the light
>generated by a red LED seems to be equal to that produced by a simiconductor
>laser.  As I understand the manufacture of laser diodes, it is a row of LEDs
>spaced so that at the trigger current the light from one LED causes the 
>neighbors
>to fire.  (If I am wrong, somebody please explain it better.)  A single LED,
>or a bank of them, may have phase noise, but I haven't seen much amateur
>equipment that could measure it.  Does anyone have equipment that will 
>work better
>with coherent light?

I think the laser is more like an amplifier, a cavity based amp. As the 
operating conditions are changed, it begins to oscillate because gain 
becomes high enough to allow it to oscillate. The point where the output 
changes from random to coherent is called the lasing threshold. The physics 
are nasty complicated, but fortunately, we don't need PHD's from Yale to 
take advantage of the recently discovered lasing phenomena.

>The idea of communicating with light seems to be suffering more from the fact
>that it is not practical to regulate who is doing it.  An amateur license is
>a grant from the government for the privilege of operating a transmission
>device.  (Some would like to make it a crime to receive radio signals without
>permission, but that is another political debate.)  Light is something 
>that comes
>and goes without much regard for legislation.  The sun comes up, I can use as
>I see fit, and am technically capable of, whatever sunbeams that happen to
>come my way.  The sun goes down, I can look at the moon and stars, again 
>within
>my technical limits.
>
>What then can the ARRL set into its rules that will separate licensed
>amateurs from tinkerers?  They are in the business of promoting amateur 
>radio, not
>light communication.


Yes, all true. But, before leaving this thread, let's not forget that 
licensed amatuers have privileges above 300 Ghz, which means RF, light, 
X-Rays etc. While there are no formal amateur regulations above 300 Ghz, it 
is still an amateur allocation.


>I have always thought that part of the reasoning for some of the light
>related rules, was that the "technology" of electronic communication could 
>not
>compete with the capability of sunlight, an eight inch mirror and human 
>eye to
>provide a communication link of 183 miles in the 1890s.  When a laser 
>experimenter
>breaks that Heliograph record with a voice contact, I will celebrate the
>technological achievement.
>
>I think that getting the ARRL to change those rules would be a lot easier if
>you could show them that if they encourage light experimentation, then the
>membership of  ARRL would grow by ten percent.


This is all painfully correct, and unfortunate for us. However, acknowledge 
of technical achievement, operating skills and/or use of amateur radio for 
public service is deeply rooted within the ARRL's frame of mind. They 
sponsor contests to encourage activity and reward good operators and 
operating skill by acknowledging it and giving awards. Even in non-contest 
amateur activity, the ARRL acknowledges public service by amateurs 
participating in public service nets and uses awards to promote additional 
activity and technical development-the DXCC award predates WW II, although 
I don't think it was formalized before the war.

We (laser operators) use the spectrum above 300 Ghz and there are quite a 
few of us now. Laser communication has evolved from theory to full 
practical uses, in much the same way that 10 Ghz has. When the ARRL's rules 
become outdated and represent an impediment to future expansion and 
activity, I think they should consider our opinions with respect to 
changing their rules regarding laser comm.

Of course, I don't care whether the guy on the other end of the path has a 
license or not.....we will always be free to do our own thing with regard 
to laser. But, I'd rather have updated acceptance criteria established by 
the ARRL so that achievements can be recognized as amateur radio 
achievements and so laser can be a practical band in UHF/microwave contests.

Clearly, this is a topic that the ARRL can't expend large amounts of 
personnel and time administrating. My idea is to work out criteria for 
light wave communication and to present it to the ARRL for their 
approval-which I think meets our needs and theirs too. Stringent standards 
are more likely to be accepted than loose ones:>:

My feeling is that wideband signal generators should be considered as 
transmitters. This applies to an LED as well as a 10 GHZ cavity with a 
microwave diode in it. It's the same concept-the first rules to go should 
be the one that requires coherent lightwave transmitters. (IMHO).

Regards,

Art