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For my project I need to design a cheap VCSEL laser driver which can be modulated up to 10 MHz. My laserdiode is VCSEL-1550 nm-T (built-in TEC and no monitordiode for APC). Datasheet link is here: https://www.oequest.com/getDatasheet/id/13138-13138.pdf.

In my previous design of the VCSEL laser driver, I have employed a laser driver IC-chip from Thorlabs with MAX1978 as TEC-controller. This works well. However, the laser driver chip is costly and is not programmable, so I am searching for alternatives.

What I have searched so far are vcsel laser drivers, for example, MAX3996CTP+, but don't suit to our application. Alternatively, ADN8810, a 12-bit programmable current source, can be used. Now, with this IC-chip I would like to use is as a VCSEL laser driver. Unfortunately, there is no modulation feature. From the internet, I have found out that you can use a bias-tee, but it's quite difficult to design for low to moderate frequencies. Is there an alternative configuration for modulating VCSEL laserdiode in combination with ADN8810?

Square wave or sine wave with a modulation bandwidth of up to 10 MHz is fine to me. My absolute maximum laser current is 25 mA, but we will only use laser currents up to 20 mA.

The block diagram of ADN8810 is seen below. enter image description here

This picture is from https://www.analog.com/media/en/technical-documentation/data-sheets/ADN8810.pdf

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  • \$\begingroup\$ You can't build your own laser driver? Is there some difficulty about laser drivers with a constant current source I am not aware of? \$\endgroup\$
    – DKNguyen
    Dec 5, 2021 at 21:26
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    \$\begingroup\$ I think a few companies have capitalized on engineers fears with respect to driving lasers or VCSELs. You don't need a specific driver. Just make sure you don't over egg the current, make sure you don't drop out of any lasering threshold and, try and alter bias current with temperature to suit the VCSEL characteristics. Fairly easy stuff really. \$\endgroup\$
    – Andy aka
    Dec 5, 2021 at 21:31
  • \$\begingroup\$ you can have it even easier, though. SFP or SFP+ modules are relatively straightforward to use, and they come with the optical connectors to couple the laser into something useful – a fiber. All you have to supply is a differential voltage signal on the TXD+/TXD- pins. \$\endgroup\$
    – Marcus Müller
    Dec 5, 2021 at 22:19
  • \$\begingroup\$ It appears that ADN8810 is not fast enough to meet your 10 MHz. modulation requirement. That doesn't prevent you from shunting its 20mA current output to GND with an external (fast) current sink. Awkward, but do-able. \$\endgroup\$
    – glen_geek
    Dec 5, 2021 at 23:46
  • \$\begingroup\$ 5MHz bandwidth won’t do 10MHz modulation, so as others suggested, look for a faster driver. \$\endgroup\$
    – 65Roadster
    Dec 6, 2021 at 5:39

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Not a solution, just some design ideas.

The Laser BW is RF Bandwidth (S21) 8.5 GHz only using their EVAL board.

See the datasheet link at the end. This data sheet describes the optical evaluation kit for the ADN2530, a 10 Gbps active back-terminated, vertical-cavity surface-emitting laser (VCSEL) driver.

Here's a snapshot of a partial schematic from the Arrow site. I would incorporate ACC mode with thermal feedback on the diode. https://www.arrow.com/en/reference-designs/eval-adn2530-aoz-optical-evaluation-kit-with-a-vcsel-laser-populated-for-the-adn2530-differential-vcsel-driver/508419eeb106511695ab855d97d28fac enter image description here

Considering low current <50mA but fast negative incremental resistance sensitivity to incremental voltage above the lasing threshold, I would consider CML drivers for current mode switching with sub-nanosecond switching times with PWM at 10 MHz carrier rates. Impedance control is critical on the path between driver and load.

Note the negative resistance slope at lasing threshold which achieves the high BW with low capacitance.

enter image description here ref

https://www.analog.com/media/en/technical-documentation/evaluation-documentation/eval_adn2530.pdf

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