Optical Parametric Oscillator (OPO) is a well-known solution when wide tunability in the mid-infrared is needed. A specific design called NesCOPO (Nested Cavity doubly resonant OPO) is currently integrated in the X-FLR8 portable gas analyzer from Blue Industry and Science. Thanks to its low threshold this OPO can be pumped by a micro-chip nanosecond YAG (4 kHz repetition rate and a 30 GHz bandwidth). To achieve very high resolution spectra (10 pm of resolution or better), the emitted wavelength has to be finely controlled. Commercial Wavemeter do not meet price and compactness required in the context of an affordable and portable gas analyzer. To overcome this issue, Blue first integrated an active wavelength controller using multiple tunable Fabry-Perot (FP) interferometers. The required resolution was achieved at a 10 Hz measurement rate. We now present an enhanced Wavemeter architecture, based on fixed FP etalons, that is 100 times faster and 2 times smaller. We avoid having FP ‘blind zones’ thanks to one source characteristic: the knowledge of the FSR (Free Spectral Range) of the OPO source and thus, the fact that only discrete wavelengths can be emitted. First results are displayed showing faster measurement for spectroscopic application, and potential future improvement of the device are discussed.
Optical Parametric Oscillator (OPO) is a well-known solution when wide tunability in the mid-infrared is needed. A specific design called NesCOPO (Nested Cavity doubly resonant OPO) is currently integrated in the X-FLR8 portable gas analyzer from Blue Industry and Science. Thanks to its low threshold this OPO can be pumped by a micro-chip nanosecond YAG (4 kHz repetition rate and a 30 GHz bandwidth). To achieve very high resolution spectra (10 pm of resolution or better), the emitted wavelength has to be finely controlled. Commercial Wavemeter do not meet price and compactness required in the context of an affordable and portable gas analyzer. To overcome this issue, Blue first integrated an active wavelength controller using multiple tunable Fabry-Perot (FP) interferometers. The required resolution was achieved at a 10 Hz measurement rate. We now present an enhanced Wavemeter architecture, based on fixed FP etalons, that is 100 times faster and 2 times smaller. We avoid having FP ‘blind zones’ thanks to one source characteristic: the knowledge of the FSR (Free Spectral Range) of the OPO source and thus, the fact that only discrete wavelengths can be emitted. First results are displayed showing faster measurement for spectroscopic application, and potential future improvement of the device are discussed.
High resolution gas spectroscopy in the mid-infrared in a transportable device is a big challenge allowing to address numerous applications: air quality or industrial process monitoring, defense and security, medical diagnostics... Together with high tunability in the mid-infrared, spectral purity, narrow bandwidth, compactness and robustness are needed. Nested Cavity doubly resonant OPO (NesCOPO) fulfill all those requirements. This architecture is already commercialized (in the X-FLR8 portable gas analyzer from Blue Industry and Science) and allows to reach low threshold compatible with the use of compact micro-chip nanosecond YAG laser.
A wide spectral range can be obtain (2 - 10 μm). In the most mature version NesCOPO takes benefit of down-conversion of a laser radiation at 1.064 μm in a PPLN bulk crystal and give rise to two secondary radiation around 1.5 μm and between 3.2 and 4.25 μm. This last radiation is used to probe rovibrational absorption lines of species of interest using absorption or transmission spectroscopy.
Speed in the selection of the emitted wavelength can be an important requirement especially when security is involved. We use engineering of the crystal using fan-out configuration. Evolution of the bandwidth and phase shift between the three waves after reflection onto the end cavity mirror has to be managed to maintain high conversion efficiency. Experiment show more flexible behavior than expected with theory. This lead to fine wavelength control on the overall emission spectrum (over 1 μm) without using crystal temperature tuning that slow down tuning speed.
High resolution gas spectroscopy in the mid-infrared in a transportable device is a big challenge allowing to address numerous applications: air quality or industrial process monitoring, defense and security, medical diagnostics... Together with high tunability in the mid-infrared, spectral purity, narrow bandwidth, compactness and robustness are needed. Nested Cavity doubly resonant OPO (NesCOPO) fulfill all those requirements. This architecture is already commercialized (in the X-FLR8 portable gas analyzer from Blue Industry and Science) and allows to reach low threshold compatible with the use of compact micro-chip nanosecond YAG laser. A wide spectral range can be obtain (2 - 10 μm). In the most mature version NesCOPO takes benefit of down-conversion of a laser radiation at 1.064 μm in a PPLN bulk crystal and give rise to two secondary radiation around 1.5 μm and between 3.2 and 4.25 μm. This last radiation is used to probe rovibrational absorption lines of species of interest using absorption or transmission spectroscopy. Speed in the selection of the emitted wavelength can be an important requirement especially when security is involved. We use engineering of the crystal using fan-out configuration. Evolution of the bandwidth and phase shift between the three waves after reflection onto the end cavity mirror has to be managed to maintain high conversion efficiency. Experiment show more flexible behavior than expected with theory. This lead to fine wavelength control on the overall emission spectrum (over 1 μm) without using crystal temperature tuning that slow down tuning speed.
Optical Parametric Oscillator (OPO) is a well-known solution when wide tunability in the mid-infrared is needed. A specific design called NesCOPO (Nested Cavity doubly resonant OPO) is currently integrated in the X-FLR8 portable gas analyzer from Blue Industry and Science. Thanks to its low threshold this OPO can be pumped by a micro-chip nanosecond YAG (4 kHz repetition rate and a 30 GHz bandwidth). To achieve very high resolution spectra (10 pm of resolution or better), the emitted wavelength has to be finely controlled. Commercial Wavemeter do not meet price and compactness required in the context of an affordable and portable gas analyzer. To overcome this issue, Blue first integrated an active wavelength controller using multiple tunable Fabry-Perot (FP) interferometers. The required resolution was achieved at a 10 Hz measurement rate. We now present an enhanced Wavemeter architecture, based on fixed FP etalons, that is 100 times faster and 2 times smaller. We avoid having FP ‘blind zones’ thanks to one source characteristic: the knowledge of the FSR (Free Spectral Range) of the OPO source and thus, the fact that only discrete wavelengths can be emitted. First results are displayed showing faster measurement for spectroscopic application, and potential future improvement of the device are discussed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.