We have just published the data sheet for our ultra
compact, hands-free mid-IR OPO, the Firefly-IR: you can access the
document in our downloads section. M Squared Lasers
is working at the forefront of the design and manufacture of
photonics devices. In the case of the Firefly-IR, we are pioneering
an intracavity design with the OPO situated inside the pump laser
resonator, obviating any need for a separate pump source and
dramatically reducing the overall footprint of the device to a mere
35 x 10 cm2. That's smaller than an average shoebox, and
with no detriment to the high peak and average power outputs which
are maintained across a broad tuning range within the
mid-infrared.
How is the Firefly different from traditional
OPO design?
The conventional design principle of an OPO is that a
single pump photon is split into two new photons of lower energy
(signal and idler) whereby the sum of their energies is equivalent
to that of the original photon. Energy and momentum are conserved
and the wave vectors are divergent, with the longer wavelength
idler beam tuneable across the mid-infrared. Traditionally, the
pump laser is separate from the OPO with the output of the former
fed into the OPO cavity. In the case of the Firefly-IR, however,
the OPO is located inside the cavity of the diode-pumped solid
state laser thus ensuring that the only exit route for laser light
from the resonator is through the OPO process: emission at the
idler and signal wavelengths.
Technical Specification
Please download the data sheet for more detailed
information. The headlines, however, are as follows:
- Standard product family based around the intracavity
design.
- High power version produces > 350mW at 3.1µm.
- Low power version produces > 80mW
- Two tuning ranges: 2.4 - 3.7µm and 1.5 - 1.8µm or 3.7 - 4.5µm
and 1.4 - 1.6µm.
- Pulsed version produces 10ns pulses at > 200W peak
power
The high peak power is a critical enabler of remote
sensing functionality, especially at long range or low
concentrations.
Usability
Aside from the portability conveyed by its
small size, the Firefly-IR is extremely user-friendly with an
interface for control over ethernet (or event Internet). It only
requires a standard web browser to "dial in" to the ICE-BLOC controller, with the laser itself
supplied as a sealed, hands-free system. A customer launches the
control page in a browser and selects the required wavelength. The
entire tuning range can be covered in less than 30
seconds.
Applications in remote sensing
Many hydrocarbons, for example hydrogen sulphide,
display strong absorption features in the Firefly-IR tuning range.
There is a notable absorption feature due to the C-H group present
in all hydrocarbons which is close to 3.3µm and also the O-H and
N-H functional groups in alcohols and amines where the absorption
features sit between 2.7 - 2.8µm and 3µm
respectively.
Typical remote sensing applications include detection
of gas leaks on oil and gas assets where the stand-off distance is
important due to the scale of the structures, and also explosives
detection where distance is crucial for user safety.
Our focus on usable applications has led us to
develop a hand-held, battery-operated stand-off imager / detector
with all required instrumentation packaged into a single box, the
whole device portable by an individual. To date, we have
demonstrated imaging and detection of specific hydrocarbons at
distances greater than 40m.
In addition to gas detection, the high spectral
brightness of the Firefly-IR enables the search for and
identification of liquid and solid contaminants, offering
applications in forensics and even the analysis of oil and acrylic
artworks.
A more detailed version of this article is available
in Laser+Photonics.