Lightwave Logic Inc (LWLG)

[Photonics_Guy]

MZM Photonics Modulator Basics

In response to your questions...

1) Slide 38 "Direct Drive" Optical Modulators the takeaway green box says >> Low voltage operation means: ‘direct drive’ ? driverless

So, what normally drives the modulator, a laser diode right? So originally I thought LWLG's "Direct Drive" was the fact it was being developed on InP where "the laser comes for free", but I think because the Voltage is so low the modulator maybe doesn't require a laser to drive it, is this possible?

There are three inputs to and one output from a photonics intensity modulator.
The inputs are: (1) the laser input (optical), (2) the modulating signal input (RF), and (3) the modulator bias (DC).
The output is the modulated signal (optical).

The whole discussion about Direct Drive and Low Vpi revolves around the magnitude of the voltage used to drive the modulator bias input (item #3 in the list of inputs above). The Modulator Bias input is a DC signal that optimally positions (biases) the modulating signal on the laser optical input signal. If the modulator has a higher Vpi, the modulator DC bias must be able to swing high enough to optimally bias the modulator. For traditional LiNb MZM modulators, this can be >5V. While the modulator bias input itself requires very little current (in the nano-amps), the circuit still requires power supplies, voltage regulators, digital-to-analog converters and output amplifiers to generate this higher voltage. All of these extraneous components require a certain amount of power to operate.

The power these other components dissipate increases approximately proportionally to the square of the voltage. Hence, to drive a modulator with a Vpi of 5V will require 25X the power of a modulator with a Vpi of 1V.

Here is a good article published by ixBlue, a LiNb MZM modulator manufacturer located in France that discusses details about biasing a modulator.

introduction-to-modulator-bias-controllers

2) Slide 41 Small size enables transceiver platforms

I keep looking at this slide in amazement because it shows the LWLG device so tiny compared to today's pluggable TXRX device and when you look to the top right of the slide it would appear that this is perhaps LWLG's first PIC proto, is that possible? and it shows 130GHz just under it, is it possible that this is a LWLG PIC proto that would fit in the tiny rectangle shown above today's pluggable device?

the takeaway green box says >>

5mm, 100Gbaud ? High density, small footprint TxRx


Ok, so then if the PIC modulator doesn't need a laser driver it could be possible that the P2IC Platform could be a reality sooner rather than later? and would it also be possible that if it were a P2IC that LWLG could have designed and fabricated a proto already in-house?

Unfortunately, no. As mentioned in the response to your first question, the input that is affected by the 'Direct Drive' is the Modulator DC Bias input. The modulator still requires a laser input.

Hope this helps.

PG