PNNL-13501 - Pacific Northwest National Laboratory

Figure 3 is a color rendered simulation of the University
of Idaho-designed modulator showing the magnitude of
the electric field in the region of the nonlinear optical
crystal.
Figure 3. Computational results showing the magnitude of
an applied electric field within the concept electro-optic
modulator designed jointly between PNNL and the
University of Idaho
Precision Pressure Control
Also tested during this fiscal year was a system designed
to precisely control the pressure within the optical cavity
during analysis. Because the length of the NICE-OHMS
optical cavity must be maintained to a high degree during
a measurement, a system needed to be developed that
allows different gas samples to be added without a
significant change in the pressure. A system was
procured which incorporates mass-flow controllers,
pressure measuring devices and a servo control unit. The
system was assembled and tested. Figure 4 is a
photograph of the assembled system. Next fiscal year a
second mass controller will be added and software written
to allow for the gradual transition from an actual sample
to a calibration sample.
Summary and Conclusions
The first phase of the development of two key
technologies necessary for the realization of an infrared
variant of a NICE-OHMS instrument have been
successfully completed. Technical milestones that have
been reached include
Figure 4. Photograph of phase-one inlet system for a QCL-
NICE-OHMS apparatus
• infrared system components (QC laser, detectors,
optical cavity) were integrated
• deleterious optical-feedback was reduced using an
acousto-optic modulator
• university collaboration successfully generated an
electro-optic modulator design
• the feedback-controlled pressure regulation system
was tested.
This project will continue with the goal of integrating the
advanced electro-optic phase modulator with the optical
cavity system and testing of the complete NICE-OHMS
signal acquisition process.
References
Drever RWP, JL Hall, FV Kowalski, J Hough, GM Ford,
AJ Munley, and H Ward. 1993. “Laser Phase and
Frequency Stabilization Using an Optical Resonator.”
Applied Physics B 31:97.
Ye J, M LS Ma, and JL. Hall. 1998. “Ultrasensitive
detections in atomic and molecular physics:
demonstration in molecular overtone spectroscopy.” J. of
the Optical Society of America, B 15:6.
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