M140 laser driver for underwater communications

I am working on an experimental project to do both underwater communications and imaging. The laser will be using a M140 455nm diode and we need a driver that has sufficient current capacity (1.5A) and high modulation rates (100MHz). I have looked at the IXLD02SI Differential Ultra Fast Laser Diode Driver that is currently discontinued and the ISL58214, but that is a bit short on current. Do any of you know of a suitable driver IC/board/module that I could get my hands on?
The imaging part of the project will use a DLP mirror system for scanning . The communications part will use a diffuser to create a wide beam to eliminate the need for accurate pointing and tracking.

The IXLD02SI should do the trick I see that version is not discontinued and you can still indeed purchase it, I found it on alibaba in a quick google search & it should provide the specs you want to acheive :beer:
Your project sounds cool keep us informed

well that IC is 17Mhz tops, and I see you need 100MHz operating frequency is that right? :thinking:

I think you would be better off using a 405nm 12x diode for a number of reasons:

1) The absorption coefficient for water is lower at 405 than 445 (see: http://www.d-a-instruments.com/images/Absorption-Coefficient.gif), so 405nm light will be absorbed by the water less rapidly than 445nm.

2) A 405nm single mode diode has better beam characteristics than a 445nm multi mode diode and much higher output power than a 445nm single mode diode. A 405nm can thus maintain a higher power beam, for longer, before diverging to the degree that your detector can no longer detect it's signal. IE, it can maintain a higher energy density, longer.

3) A 405nm requires < 1/3rd the current of a 445nm multi mode diode.

Dose any one here know if a P3 driver can go to that high of freq ?

It sure can do the current and more it's cap is 4 amps, it would be
able to push 8ea 405nm LD's for greater illumination for the detector.

I will ask Dr. Lava...

^^I think the P3 is limited to ~10k if remember correctly.

**Where did I read that??

I called IXYS this afternoon and was told that the IXLD02SI was discontinued, no longer available, and that the eval board was sold out. It would have been good for preliminary testing at 17 MHz. The P3 board is much lower in frequency as noted above. Intersil said that they might have a new chip coming out, the ISL58303, but so far they haven't come through with a data sheet. I had to sign a non disclosure agreement to even get the data sheet.

candren said:

I called IXYS this afternoon and was told that the IXLD02SI was discontinued, no longer available, and that the eval board was sold out. It would have been good for preliminary testing at 17 MHz. The P3 board is much lower in frequency as noted above. Intersil said that they might have a new chip coming out, the ISL58303, but so far they haven't come through with a data sheet. I had to sign a non disclosure agreement to even get the data sheet.

Click to expand...

I think you could use an electro-optical modulator to achieve RF modulation (you say 100 MHz...) and to relax the design of diode driver.
Here you can find a laser home theater project using a brewster angle modulator at 350MHz.
As an example qioptiq offers laser modulators.

RHD,
We will be operating in ocean water, so the best color is 532nm for coastal waters and 455nm for deep ocean. The better physical characteristics of 405nm are desirable but the extra phytoplankton loss is not.