I would like know how we can compress microsecond duration laser pulses by a factor of 1000 for a commercial aviation industry application.
Dr. Stephen Roberson Ph.D. and Dr Paul Pelligrino Ph.D. wrote in a 2016 U.S Army Research Library unclassified technical report titled "Compression of Ultrafast Laser Beams" that
A pulsed laser is normally considered an ultrafast pulsed laser when
the pulse duration of that laser is in the realm of picoseconds and
below. Ultrashort laser pulses deliver a very high peak power to their
targets because of their short durations.
Professor Aaron Lindenburg, et al. from Stanford University wrote a 2016 Physics Review Letter article titled "Picosecond electric-field-induced threshold switching in phase-change materials" that
It is well known that the electric field required for threshold
switching increases for short pulse durations.
If it is possible, I would like to use pulse compression to generate $1\ \text{nanosecond}$ duration pulses from $1\ \text{microsecond}$ laser pulses in order to reduce the required $340\ \text{kilovolts per centimeter}$ DC or AC electric field strengths.
In Dr. Arbore's article, the Stanford University researchers use second harmonic generation in chirped quasi-phase matching diffraction gratings to compress $17\ \text{picosecond}$ duration pulses to $110\ \text{femtosecond}$ duration pulses. I wish to find out why all the literature searches I have done discuss pulse compression of ultrafast pulsed lasers only when the pulse duration of that laser is in the realm of picoseconds and below.
We are using a simple pulsed CO2 laser with long pulse duration of millisecond order in a tube at a low pressure of less than $30\ \text{torr}$. The power supply for our laser system switches the voltage of the AC power line ($60\ \mathrm{Hz}$) directly. The power supply does not need elements such as a rectifier bridge, energy-storage capacitors, or a current-limiting resistor in the discharge circuit. In order to control the laser output power, the pulse repetition rate is adjusted up to $60\ \mathrm{Hz}$ and the firing angle of the silicon controlled rectifier (SCR) gate is varied from $30°$ to $150°$. The maximum laser output of $35\ \mathrm{W}$ is obtained at a total pressure of $18\ \text{torr}$, a pulse repetition rate of $60\ \mathrm{Hz}$, and a SCR gate firing angle of $90°$. In addition, the resulting laser pulse width is approximately $3\ \mathrm{ms}$ (full width at half maximum). This is a relatively long pulse width, compared with other repetitively pulsed CO2 lasers.
The amorphous semiconductor used by the Stanford University researchers was first used by Dr Stanford R. Ovshinsky Ph.D. The problem that held back large scale usage of the Ovshinsky diode was poor reliability. It would be very difficult to obtain F.A.A approval for using such an amorphous semiconductor device in the cockpit.
Time-bandwidth product
The time-bandwidth product of a pulse is the product of its temporal duration and spectral width (in Frequency space). In ultrafast Laser physics, it is common to specify the full width at half maximum (FWHM) both in time and frequency domain. The minimum possible time-bandwidth product is obtained for bandwidth-limited pulses. For example, it is ≈0.315 for bandwidth-limited sech2-shaped Pulses or ≈0.44 for Gaussian-shaped pulses. This means e.g. that for a given spectral width, there is a lower limit for the pulse duration. This limitation is essentially a property of the Fourier transform.
Here is the bandwidth specification and calculation I was hoping could
be considered further if we can ignore the laser amplifier gain bandwidth product.
For a 1 microsecond laser pulse duration,
$$\text{bandwidth} = \frac{0.44}{1\times 10^{-6}\ \mathrm{s}} = 4.4 \times 10^7\ \mathrm{Hz}\ \text{FWHM}$$
so full width half maximum is 44 Megahertz (MHz).
Best Answer
So this is a discharge pumped laser.
At 18 Torr the laser lines will be quite narrow. Do you know how much bandwidth you have in your current output pulses? I think this is important.
You may have the needed bandwidth (~1/1us). If so, then I'll look from a crystal with anomalous dispersion for the compression.
If you do not have the bandwidth then you need to create the bandwidth (see https://en.m.wikipedia.org/wiki/Bandwidth-limited_pulse). I am thinking pressure broadening the spectral lines at 10um is the way to go. If you do not have the bandwidth then compression isn't possible.
( this is the beginning of a full answer. I didn't want the comments to keep expanding)