Continuous-wave Optical Parametric Oscillators and Frequency Conversion Sources from the Ultraviolet to the Mid-infrared PDF Download
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Author: Kavita Devi
Publisher:
ISBN:
Category :
Languages : en
Pages : 205
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High-power, continuous-wave (cw) optical parametric oscillators (OPOs), from the ultraviolet (UV) and visible to the near- and mid-infrared (IR) wavelength range, are of interest for a variety of applications such as spectroscopy, trace-gas detection and remote sensing. As such, it is desired to investigate OPOs and different frequency conversion techniques, to cover the spectral regions that are inaccessible to lasers, and that too in a compact and low-cost design. This thesis presents the development of high-power cw OPOs, and frequency conversion sources, spanning the UV to mid-IR spectral range, employing different designs, experimental configurations and nonlinear crystals, making them compact and cost-effective. Commercial high-power cw lasers at 1940 nm, 1064 nm and 532 nm have been exploited as the pump sources, in the work presented in this thesis. We have demonstrated a fiber-based cw source at 970 nm, in a simple and practical design. Using direct single-pass second-harmonic-generation (SHG), 13.1 W of output power at 970 nm has been generated in a high-beam-quality, narrow-linewidth, linearly-polarized beam. Further, a technique based on the use of an antiresonant ring (ARR) interferometer for the attainment of optimum output coupling in a cw singly-resonant OPO has been investigated. The technique was deployed in a Yb-fiber-laser-pumped cw OPO based on MgO:PPLN. To extend the tunability of the 1-μm-pumped OPO from the mid-IR to near-IR, SHG of the intracavity signal has been performed in fanout-grating MgO:sPPLT. This compact cw source, tunable across 775¿807 nm, provides >3 W of near-infrared power across 56% of SHG tuning range, in high spatial beam quality. We have also generated output in the UV, down to 355 nm, using single-pass configuration based on sum-frequency-generation of fundamental at 1064 nm and the generated SHG at 532 nm, in BiB3O6. Further, we demonstrated an architecture comprising two cw OPOs coupled together with an ARR interferometer, generating two pairs of signal and idler wavelengths, that can be independently and arbitrarily tuned to indefinitely close spacing, through degeneracy, and beyond, across the wavelength range of 870-1370 nm. The OPOs, based on identical MgO:sPPLT crystals, were pumped by a single cw laser at 532 nm. On the other hand, we also demonstrated active mode-locking of cw OPOs using direct low-frequency electrooptic phase-modulation (EOM), opening up the possibility of avoiding the need for ultrafast laser sources and synchronous pumping. We have generated picosecond pulses in doubly- and singly-resonant configuration. Also, a technique based on the deployment of the EOM in combination with an ARR interferometer internal to the cw OPO has been investigated for active modelocking.
Author: Kavita Devi
Publisher:
ISBN:
Category :
Languages : en
Pages : 205
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Book Description
High-power, continuous-wave (cw) optical parametric oscillators (OPOs), from the ultraviolet (UV) and visible to the near- and mid-infrared (IR) wavelength range, are of interest for a variety of applications such as spectroscopy, trace-gas detection and remote sensing. As such, it is desired to investigate OPOs and different frequency conversion techniques, to cover the spectral regions that are inaccessible to lasers, and that too in a compact and low-cost design. This thesis presents the development of high-power cw OPOs, and frequency conversion sources, spanning the UV to mid-IR spectral range, employing different designs, experimental configurations and nonlinear crystals, making them compact and cost-effective. Commercial high-power cw lasers at 1940 nm, 1064 nm and 532 nm have been exploited as the pump sources, in the work presented in this thesis. We have demonstrated a fiber-based cw source at 970 nm, in a simple and practical design. Using direct single-pass second-harmonic-generation (SHG), 13.1 W of output power at 970 nm has been generated in a high-beam-quality, narrow-linewidth, linearly-polarized beam. Further, a technique based on the use of an antiresonant ring (ARR) interferometer for the attainment of optimum output coupling in a cw singly-resonant OPO has been investigated. The technique was deployed in a Yb-fiber-laser-pumped cw OPO based on MgO:PPLN. To extend the tunability of the 1-μm-pumped OPO from the mid-IR to near-IR, SHG of the intracavity signal has been performed in fanout-grating MgO:sPPLT. This compact cw source, tunable across 775¿807 nm, provides >3 W of near-infrared power across 56% of SHG tuning range, in high spatial beam quality. We have also generated output in the UV, down to 355 nm, using single-pass configuration based on sum-frequency-generation of fundamental at 1064 nm and the generated SHG at 532 nm, in BiB3O6. Further, we demonstrated an architecture comprising two cw OPOs coupled together with an ARR interferometer, generating two pairs of signal and idler wavelengths, that can be independently and arbitrarily tuned to indefinitely close spacing, through degeneracy, and beyond, across the wavelength range of 870-1370 nm. The OPOs, based on identical MgO:sPPLT crystals, were pumped by a single cw laser at 532 nm. On the other hand, we also demonstrated active mode-locking of cw OPOs using direct low-frequency electrooptic phase-modulation (EOM), opening up the possibility of avoiding the need for ultrafast laser sources and synchronous pumping. We have generated picosecond pulses in doubly- and singly-resonant configuration. Also, a technique based on the deployment of the EOM in combination with an ARR interferometer internal to the cw OPO has been investigated for active modelocking.
Author: Anuja Arun Padhye
Publisher:
ISBN:
Category :
Languages : en
Pages : 167
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Book Description
The ability to manipulate frequency of light, through parametric frequency conversion sources based on X(2) nonlinear materials, offers an effective route to spectral regions unapproachable by conventional lasers. Most importantly, three-wave mixing processes provide tunable coherent radiation over a broad spectral range. Among the most important tunable devices, narrow linewidth continuous-wave (cw) infrared (IR) optical parametric oscillators (OPOs) are indispensable excitation sources for many applications in molecular spectroscopy and precision metrology. In order to exploit such applications, the development of cw OPOs deploying different wavelength tuning schemes and novel nonlinear materials is highly dezirable, as presented in this thesis. We demonstrated a rapidly tunable cw OPO based on fan-out grating design periodically-poled KTiOPO4 (PPKTP) crystal at room temperature. This approach allows continuous wavelength tuning by avoiding increased thermal fluctuations at higher operating crystal temperatures. The 532 nm-pumped, output-coupled singly-resonant oscillator (OC-SRO) provides widely tunable near-IR radiation across 741-922 nm and 1258-1884 nm, with total output power of 1.65 W. The use of output coupling for the resonating wave reduces thermal loading and enables 30% enhancement in the OPO extraction efficiency over the pure SRO configuration. Towards the goal of developing a next-generation cw source >4 μm using a new found quasi-phase-matched semiconductor material, orientation-patterned gallium phosphide (OP-GaP), we demonstrated the first realization of a tunable cw mid-IR source based on OP-GaP by exploiting single-pass difference-frequency-generation (DFG) between a Tm-fiber laser at 2010 nm and a home-built OPO based on MgO-doped periodically-poled LiNbO3 (MgO:PPLN) crystal. The DFG source generates up to 43 mW of output power, with >30 mW across 96% of the tuning range 4608-4694 nm, in high beam quality. As the tunable mid-IR sources are making great strides, the availabilityof fast and sensitive mid-IR detectors become equally important. However, the conventional mid-IR detectors demand cryogenic systems for low-noise operation which sets a major drawback as these devices are often bulky and expensive. In this context, the nonlinear frequency upconversion technique has emerged as a promising alternative to the direct detection of mid-IR radiation at room temperature. An upconversion detector (UCD) can be further optimized by identifying and suppressing its noise sources. In order to do so, we experimentally and theoretically investigated noise properties of 1064 nm-pumped single-pass UCD designed for signal detection in telecom and mid-IR range using MgO:PPLN crystals. We studied the dependence of newly discovered SHG (532 nm)-induced spontaneous parametric downconversion (SHG-SPDC) noise intensity on the pump power and crystal temperature, and compared it with the well-known UCD noise source upconverted spontaneous parametric downconversion (USPDC). The measurements deduce that SHG-SPDC must be given a careful consideration since it can act as a dominant noise source under certain operating conditions. However, SHG-SPDC can be avoided by choosing a proper combination of MgO:PPLN grating period,operating temperature, and bandpass filter.
Author: Rosita Sowade
Publisher: Sudwestdeutscher Verlag Fur Hochschulschriften AG
ISBN: 9783838126951
Category :
Languages : de
Pages : 104
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Book Description
Continuous-wave (cw) optical parametric oscillators (OPOs) are working horses for spectroscopy for near and mid infrared wavelengths. However, in the terahertz frequency range (0.1 to 10 THz), the pump threshold for oscillation is larger than 100 W due to high absorptions and thus exceeds the power of standard cw single-frequency pump sources. In this thesis, the first cw OPO capable of generating terahertz radiation is demonstrated. To overcome thethreshold, the signal wave of a primary infrared process is resonantly enhanced to serve as a pump wave for a cascaded parametric process with one wave being at the terahertz frequency level. Such a device inhibits high potential for applications in areas like astronomy, telecommunications or high-resolution spectroscopy.
Author:
Publisher:
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Category :
Languages : en
Pages : 6
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We have achieved 150 mW of cw output at 4.3 micrometers, using difference frequency mixing in a singly resonant optical parametric oscillator (OPO). We pumped the OPO cavity, which contains periodically poled LiNbO3 (PPLN), with a 14-W 1.06-micrometers Nd:YAG laser to generate a signal at 1.7 micrometers and an idler at 2.8 micrometers. Mixing of the two waves at the same crystal temperature and grating spacing yielded emission in the mid IR. This technique avoids the mid-IR absorption-high-threshold problem, which has limited the cw performance of PPLN OPOs at wavelengths beyond 4 micrometers. Provided that tunability is not required, this method is a simple alternative to multiple-crystal configurations.
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ISBN:
Category :
Languages : en
Pages : 0
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Continuously tunable cw emission near 4.5 micrometer was generated by difference frequency generation (DFG) within a Nd:YAG pumped optical parametric oscillator (OPO). The periodically poled lithium niobate crystal used for DFO contained eight grating bands that enabled wavelength tuning between 4.25 and 5.65 micrometer. As much as 90 mW of power at 4.48 micrometer was achieved for 16.7 W of pump.
Author: Goutam Kumar Samanta
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Stanford University Ginzton Laboratory
Publisher:
ISBN:
Category :
Languages : en
Pages : 34
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The primary goal of this contract is research studies of tunable optical sources, and the development of coherent sources in new spectral regions. In particular, a major project this year has been IR image up-conversion based on three frequency summing in metal vapors. A general theory of the efficiency of these up-converters as a function of the pump laser spectrum, detuning, and linewidth, and of the linewidth of the selected non-allowed atomic transition has been developed. (Author).
Author: Stanford University. Microwave Laboratory
Publisher:
ISBN:
Category :
Languages : en
Pages : 154
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The purpose of the research performed under this program is to investigate and demonstrate tunable coherent infrared sources. The program consists of three parts: infrared generation in CdSe by parametric oscillation and by mixing, infrared generation in the new chalcopyrite nonlinear materials, and generation by stimulated Compton scattering (SCS). The first two parts of this program have been experimentally investigated with significant results demonstrated during the year. The third part of the program consists of a thorough theoretical study of the prospects for Stimulated Compton Scattering.
Author: Stefan Welzel
Publisher: Logos Verlag Berlin GmbH
ISBN: 3832523456
Category : Science
Languages : en
Pages : 198
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Book Description
Infrared laser absorption spectroscopy (IRLAS) employing both tuneable diode and quantum cascade lasers (TDLs, QCLs) has been applied with both high sensitivity and high time resolution to plasma diagnostics and trace gas measurements. TDLAS combined with a conventional White type multiple pass cell was used to detect up to 13 constituent molecular species in low pressure Ar/H2/N2/O2 and Ar/CH4/N2/O2 microwave discharges, among them the main products such as H2O, NH3, NO and CO, HCN respectively. The hydroxyl radical has been measured in the mid infrared (MIR) spectral range in-situ in both plasmas yielding number densities of between 1011 ... 1012 cm-3. Strong indications of surface dominated formation of either NH3 or N2O and NO were found in the H2-N2-O2 system. In methane containing plasmas a transition between deposition and etching conditions and generally an incomplete oxidation of the precursor were observed. The application of QCLs for IRLAS under low pressure conditions employing the most common tuning approaches has been investigated in detail. A new method of analysing absorption features quantitatively when the rapid passage effect is present is proposed. If power saturation is negligible, integrating the undisturbed half of the line profile yields accurate number densities without calibrating the system. By means of a time resolved analysis of individual chirped QCL pulses the main reasons for increased effective laser line widths could be identified. Apart from the well-known frequency down chirp non-linear absorption phenomena and bandwidth limitations of the detection system may significantly degrade the performance and accuracy of inter pulse spectrometers. The minimum analogue bandwidth of the entire system should normally not fall below 250 MHz. QCLAS using pulsed lasers has been used for highly time resolved measurements in reactive plasmas for the first time enabling a time resolution down to about 100 ns to be achieved. A temperature increase of typically less than 50 K has been established for pulsed DC discharges containing Ar/N2 and traces of NO. The main NO production and depletion reactions have been identified from a comparison of model calculations and time resolved measurements in plasma pulses of up to 100 ms. Considerable NO struction is observed after 5 ... 10 ms due to the impact of N atoms. Finally, thermoelectrically cooled pulsed and continuous wave (cw) QCLs have been employed for high finesse cavity absorption spectroscopy in the MIR. Cavity ring down spectroscopy (CRDS) has been performed with pulsed QCLs and was found to be limited by the intrinsic frequency chirp of the laser suppressing an efficient intensity build-up inside the cavity. Consequently the accuracy and advantage of an absolute internal absorption calibration is not achievable. A room temperature cw QCL was used in a complementary cavity enhanced absorption spectroscopy (CEAS) configuration which was equipped with different cavities of up to 1.3 m length. This spectrometer yielded path lengths of up to 4 km and a noise equivalent absorption down to 4 x 10-8 cm-1Hz-1/2. The corresponding molecular concentration detection limit (e.g. for CH4, N2O and C2H2 at 1303 cm-1/7.66 Aem) was generally below 1 x 1010 cm-3 for 1 s integration times and one order of magnitude less for 30 s integration times. The main limiting factor for achieving even higher sensitivity is the residual mode noise of the cavity. Employing a 0.5 m long cavity the achieved sensitivity was good enough for the selective measurement of trace atmospheric constituents at 2.2 mbar.
Author:
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Languages : en
Pages :
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A number of applications would benefit from sources of tunable coherent ultraviolet (uv) radiation in the 250 to 400 nm range. Among these are uv fluorescence laser detection and ranging (LIDAR). Other applications such as photolithography could use a fixed-frequency solid-state equivalent to excimer lasers. Broad tunability in this wavelength region has generally been accessed by frequency doubling tunable visible or near infrared lasers or by frequency mixing these lasers with the harmonics of a Nd:YAG laser. Unfortunately, to cover the full wavelength range requires multiple dye changes and/or multiple nonlinear crystals because of the relatively narrow tuning range of any one laser medium. The use of optical parametric oscillators (OPO's) with their wide tuning range as a tunable source of near infrared light coupled with a single [beta]-barium borate (BBO) crystal for sum frequency mixing with the Nd:YAG harmonics should yield a convenient alternative to cover this wavelength range. In this paper we demonstrate that an OPO can be efficiently sum frequency mixed with the Nd:YAG harmonics to produce tunable uv radiation in the 250--400 nm range. This is significant because OPO's generally have poor beam quality which limits their nonlinear conversion in critically phase matched processes. Specifically, we have mixed the 780 nm signal beam from a potassium tytanyl phosphate (KTP) OPO with the second harmonic from a Nd:YAG laser in BBO converting up to 50% of the OPO photons into 316 nm photons. We have also demonstrated the generation of narrow bandwidth 248 nm by mixing 827 nm from the OPO with the third harmonic of the Nd:YAG.
