Prev: DELL DC PLUG ?
Next: EFD20 Bobbin?
From: Joerg on 6 May 2010 15:29
John Larkin wrote:
> On Thu, 6 May 2010 07:25:33 -0700 (PDT), Rafael Palacio
> <rafael.palacio(a)gmail.com> wrote:
>
>>
>>
>> Hi,
>>
>> I've been searching for a while on the Web but all
>> manufacturers(Analog,Texas,Maxim,...) offer only digital solutions or
>> low freq(tens of Khz) analog modulation.
>> Does anyone know a LD Driver IC with analog modulation capability up
>> to 2Ghz ?
>> I want to assembly an small demo board on FR4 with some TO-can Laser
>> diodes but I dont find any solution to provide a high freq analog
>> modulation.
>>
>> Thanks a lot.
>> Regards,
>> Rafael
>
> How much current do you need? What kind of laser?
>
> An analog laser diode driver is as simple as a signal and a resistor.
>
> If you need gain, there are tons of cheap MMICs that have 6-12 GHz
> bandwidth. Just stick the laser diode in series with the output pullup
> resistor, or AC couple the MMIC output into the laser and provide a
> separate DC bias path. Check out the MiniCircuits parts.
>
> Most lasers don't modulate very well. They tend to have mode jumps,
> "kinks", in their current-to-light curve. The high-end optical RF
> links use CW lasers and lithium niobate modulators.
>

VCSELs can be fairly benign in that respect but they do have mild
polarization mode hops.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
From: Joerg on 6 May 2010 17:23
John Devereux wrote:
> Joerg <invalid(a)invalid.invalid> writes:
>
>> John Larkin wrote:
>>> On Thu, 6 May 2010 07:25:33 -0700 (PDT), Rafael Palacio
>>> <rafael.palacio(a)gmail.com> wrote:
>>>
>>>>
>>>> Hi,
>>>>
>>>> I've been searching for a while on the Web but all
>>>> manufacturers(Analog,Texas,Maxim,...) offer only digital solutions or
>>>> low freq(tens of Khz) analog modulation.
>>>> Does anyone know a LD Driver IC with analog modulation capability up
>>>> to 2Ghz ?
>>>> I want to assembly an small demo board on FR4 with some TO-can Laser
>>>> diodes but I dont find any solution to provide a high freq analog
>>>> modulation.
>>>>
>>>> Thanks a lot.
>>>> Regards,
>>>> Rafael
>>> How much current do you need? What kind of laser?
>>>
>>> An analog laser diode driver is as simple as a signal and a resistor.
>>>
>>> If you need gain, there are tons of cheap MMICs that have 6-12 GHz
>>> bandwidth. Just stick the laser diode in series with the output pullup
>>> resistor, or AC couple the MMIC output into the laser and provide a
>>> separate DC bias path. Check out the MiniCircuits parts.
>>>
>>> Most lasers don't modulate very well. They tend to have mode jumps,
>>> "kinks", in their current-to-light curve. The high-end optical RF
>>> links use CW lasers and lithium niobate modulators.
>>>
>> VCSELs can be fairly benign in that respect but they do have mild
>> polarization mode hops.
>
> Strong modulation should in itself reduce or eliminate mode hops (see
> Phil Hobbs' book). AIUI the "modes" then don't have time to get
> going. Needs to be a few hundred MHz or above.
>

It's like going over a washboard road. Above a certain speed the
rattling in the car is "gone". But the car's handling gets iffy and it
is much more prone to unauthorized departures from the road :-)

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
 | 
Pages: 1
Prev: DELL DC PLUG ?
Next: EFD20 Bobbin?