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  • 1. Agate, B.
    et al.
    Rafailov, E. U.
    Sibbett, W.
    Saltiel, S. M.
    Koynov, K.
    Tiihonen, Mikael
    KTH, Superseded Departments, Physics.
    Wang, Shunhua
    KTH, Superseded Departments, Physics.
    Laurell, Fredrik
    KTH, Superseded Departments, Physics.
    Battle, P.
    Fry, T.
    Roberts, T.
    Noonan, E.
    Portable ultrafast blue light sources2004In: OSA Trends Opt. Photonics Series, 2004, p. 651-652Conference paper (Refereed)
    Abstract [en]

    An effective means of achieving a portable, ultrafast blue-light source using a variety of nonlinear media is demonstrated. We investigate the relative merits of aperiodically-poled bulk and waveguide nonlinear crystals in comparison to periodically-poled structures.

  • 2. Agate, B.
    et al.
    Rafailov, E. U.
    Sibbett, W.
    Saltiel, S. M.
    Koynov, K.
    Tiihonen, Mikael
    KTH, Superseded Departments, Physics.
    Wang, Shunhua
    KTH, Superseded Departments, Physics.
    Laurell, Fredrik
    KTH, Superseded Departments, Physics.
    Battle, P.
    Fry, T.
    Roberts, T.
    Noonan, E.
    Portable ultrafast blue light sources designed with frequency doubling in KTP and KNbO32004In: IEEE Journal of Selected Topics in Quantum Electronics, ISSN 1077-260X, E-ISSN 1558-4542, Vol. 10, no 6, p. 1268-1276Article in journal (Refereed)
    Abstract [en]

    We demonstrate an effective means of achieving compact, truly portable, and entirely self-contained ultrafast blue light sources. Using a variety of nonlinear media to achieve simple second-harmonic generation of a femtosecond Cr:LiSAF laser, we investigate the relative merits of aperiodically poled bulk and waveguide nonlinear crystals in comparison to periodically poled structures. Such a compact and convenient source of ultrashort laser pulses in the blue spectral region could be of great interest for on-site applications spanning a host of disciplines, such as biomedical imaging, optical micromanipulation, and high-resolution spectroscopy.

  • 3.
    Henriksson, Markus
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics. Swedish Defence Research Agency, Linköping, Sweden.
    Sjöqvist, L.
    Tiihonen, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Tandem OPO systems for mid-infrared generation using quasi phase-matching and volume Bragg gratings2007In: Proceedings of SPIE - The International Society for Optical Engineering, SPIE - International Society for Optical Engineering, 2007, Vol. 6738, p. 73805-73805Conference paper (Refereed)
    Abstract [en]

    Efficient laser sources in the 3 - 5 μm wavelength range are needed for directed infrared countermeasures, but also have applications in remote sensing, medicine and spectroscopy. We present results and discuss the possibilities of a tandem optical parametric oscillator (OPO) scheme for converting the radiation from a 1.06 μm Nd3+-laser to the mid-infrared. Our setup uses type I quasi phase-matched (QPM) crystals in a near degenerate OPO to generate 2.13 μm radiation. The QPM crystal provides higher nonlinearity and longer interaction lengths, because walk-off is avoided, compared to conventional bulk crystals. This is an advantage especially in low pulse energy applications. To make the 2.13 μm radiation usable for pumping a second OPO a volume Bragg grating is used as a cavity mirror to limit the bandwidth, which in a conventional QPM OPO at degeneracy can be several hundred nanometers. The acceptance bandwidth for efficient OPO operation of a 14 mm long ZnGeP2 (ZGP) crystal is approximately 5 nm, which makes the need for bandwidth limiting clear. The majority of the signal energy from a periodically poled KTiOPO4 (PP KTP) OPO with a volume Bragg grating output coupler was found to be in a single longitudinal mode, whereas the idler bandwidth was measured to 19 GHz (FWHM). A volume Bragg grating resonant near 2124 nm was chosen so that the signal and idler were separated by 9 nm. This OPO output has been used as a pump source for a conventional ZGP OPO demonstrating efficient conversion and providing broadband tunable output in the mid-infrared.

  • 4.
    Henriksson, Markus
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Tiihonen, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Mid-infrared ZGP OPO pumped by near-degenerate narrowband type-I PPKTP parametric oscillator.2007In: Applied physics. B, Lasers and optics (Print), ISSN 0946-2171, E-ISSN 1432-0649, Vol. 88, no 1, p. 37-41Article in journal (Refereed)
    Abstract [en]

    The total pulse energy of the signal and idler in a near-degenerate type-I periodically poled KTiOPO4 (PPKTP) optical parametrical oscillator (OPO) was spectrally confined within a 2 nm spectral bandwidth at 2.13 mu m. This was achieved by using a volume Bragg grating as the output coupler. Both the signal and the idler from the PPKTP OPO were then simultaneously used to pump a mid-infrared ZnGeP2 (ZGP) OPO. The 2 nm bandwidth was narrower than the ZGP crystal acceptance bandwidth and, thus, made efficient conversion in the second OPO possible. A total slope efficiency of 10% from 1.06 mu m to the 3.5-5 mu m region was demonstrated, generating 250 mu J in the mid-IR with only 3.6 mJ of 1.06 mu m pump energy. This corresponds to a Nd:YAG pump to mid-IR conversion efficiency of 7%.

  • 5.
    Henriksson, Markus
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Tiihonen, Mikael
    KTH, School of Engineering Sciences (SCI), Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Physics.
    Mid-IR ZGP-OPO pumped by a Bragg grating line-narrowed PPKTP-OPO2006In: Conf. Lasers Electro-Opt. Quantum Electron. Laser Sci. Conf., CLEO/QELS, 2006Conference paper (Refereed)
    Abstract [en]

    Here we report on a tandem OPO consisting of a Type IPPKTP-OPO pumping a ZGP-OPO generating radiation in the mid-IR. The PPKTP-OPO uses a bulk Bragg grating to generate narrowband pump radiation at 2008 nm.

  • 6.
    Henriksson, Markus
    et al.
    FOI.
    Tiihonen, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    ZGP Mid-infrared laser source pumped by nearly-degenerate PPKTP parametric oscillator2007In: Optics InfoBase Conference Papers, Optical Society of America, 2007Conference paper (Refereed)
  • 7. Henriksson, Markus
    et al.
    Tiihonen, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    ZnGeP2 parametric oscillator pumped by a linewidth-narrowed parametric 2 μm source2006In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 31, p. 1878-1880Article in journal (Refereed)
    Abstract [en]

    A tandem optical parametric oscillator (OPO) is used to convert radiation from 1.064 μm to the mid-infrared. Spectral bandwidth narrowing close to 80 times compared with a conventional cavity was achieved by using a bulk Bragg grating as an outcoupler in a near-degenerate periodically poled KTiOPO4 OPO. The narrowed 2008 nm radiation was subsequently used for pumping the ZnGeP2 OPO, which was tunable between 3.3 and 5.2 μm. Pulse energies of 170 μJ and pump depletion close to 70% were obtained in the ZnGeP2 OPO. To our knowledge this is the first time the output from a near-degenerate type I PPKTP OPO has been used for ZnGeP2 OPO pumping.

  • 8.
    Jacobsson, Björn
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Tiihonen, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Narrowband bulk Bragg grating optical parametric oscillator2005In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 30, no 17, p. 2281-2283Article in journal (Refereed)
    Abstract [en]

    A narrowband, pulsed optical parametric oscillator (OPO) whose output coupler is a bulk glass Bragg grating is demonstrated. The OPO is based on periodically poled KTiOPO4 and is pumped by a pulsed, frequency-doubled Nd:YAG laser at 532 nm, generating a signal at 975 nm with a total efficiency of 35%. This novel and compact device shows a spectral bandwidth of 0.16 nm (50 GHz), a decrease by a factor of 20 compared with that when a conventional mirror is used. By using a folded cavity, we demonstrate tunable radiation with a tuning range of 60 nm and maintained spectral bandwidth.

  • 9.
    Jacobsson, Björn
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Tiihonen, Mikael
    KTH, School of Engineering Sciences (SCI), Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Physics.
    Narrowband optical parametric oscillator using a bulk Bragg grating2005In: Conference on Lasers and Electro-Optics Europe: Technical Digest, 2005Conference paper (Refereed)
    Abstract [en]

    We demonstrate a narrow bandwidth optical parametric oscillator (OPO) in a compact setup with a bulk Bragg grating as outcoupler reaching a signal bandwidth of 0.18 nm at 975 nm.

  • 10. Jonsson, P.
    et al.
    Kullander, F.
    Tiihonen, Mikael
    KTH, School of Engineering Sciences (SCI), Physics.
    Nordstrand, M.
    Tjærnhage, T.
    Wæsterby, P.
    Olofsson, G.
    Lindgren, M.
    Development of fluorescence-based LIDAR technology for biological sensing2005In: 2005 MRS Spring Meeting - Symposium FF: Advanced Devices and Materials for Laser Remote Sensing, Materials Research Society, 2005, p. 51-62Conference paper (Refereed)
    Abstract [en]

    Results of our on-going development of biological warfare agents (BWA) detection systems based on spectral detection of ultraviolet (UV) laser induced fluorescence (LIF) are presented. A compact optical parametric oscillator (OPO) with intracavity sum-frequency mixing (SFM) to generate 293 nm UV laser irradiation was developed. The OPO/SFM device was pumped by a diode-pumped Nd:YAG laser (1064 nm), including subsequent second-harmonic generation (SHG) in an external periodically poled KTiOPO4 (PPKTP) crystal. The laser generated 1.8 ns pulses at 100 Hz with an average power of 44 mW at 532 nm. The whole system could be used to deliver approximately 30 μJ laser irradiation per pulse (100 Hz) at 293 nm. The spectral detection part of the system consists of a grating and a photomultiplier tube (PMT) array with 32 channels, which can measure fluorescence spectra in the wavelength band from 250 nm to 800 nm. The detector system was designed along with a trigger laser to enable measurement of fluorescence spectra from an individual aerosol particle of simulants for BWA upon excitation with a single nanosecond laser pulse. We demonstrate the successful detection and spectral characterization of simulants for BWA, i.e., Bacillus atrophaeus (BG), Bacillus thuringiensis (BT), and Ovalbumin (OA).

  • 11. Jonsson, P.
    et al.
    Kullander, F.
    Vahlberg, C.
    Jelger, Pär
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Tiihonen, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Wästerby, P.
    Tjärnhage, T.
    Lindgren, M.
    Spectral detection of ultraviolet laser induced fluorescence from individual bioaerosol particles2006In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 6398Article in journal (Refereed)
    Abstract [en]

    We present results of a measurement system designed for detecting the fluorescence spectrum of individual aerosol particles of biological warfare agents excited with laser pulses at wavelengths around 290 or 340 nm. The biological aerosol is prepared and directed into a narrow air beam. A red laser is focused on the aerosol beam and a trigger photomultiplier tube monitor the presence of individual particles by measuring the scattered light. When a particle is present in the detection volume, a laser pulse is triggered from an ultraviolet laser and the fluorescence spectrum is acquired with a spectrometer based on a diffraction grating and a 32 channels photomultiplier tube array with single-photon sensitivity. The spectrometer measures the fluorescence spectra in the wavelength region from 300 to 800 nm. In the experiment we used different simulants of biological warfare agents. These bioaerosol particles were excited by a commercial available gas laser (337 nm), or a laser (290 nm) that we have developed based on an optical parametric oscillator with intracavity sum-frequency mixing. In the analysis of the experiments we compare the measured signals (fluorescence spectra, total fluorescence energy and the scattered energy) from the individual bioaerosol particles excited with the two different ultraviolet wavelengths.

  • 12. Jonsson, P.
    et al.
    Kullander, F.
    Wästerby, P.
    Tiihonen, Mikael
    KTH, School of Engineering Sciences (SCI), Physics.
    Lindgren, M.
    Detection of fluorescence spectra of individual bioaerosol particles2005In: Proc SPIE Int Soc Opt Eng, 2005Conference paper (Refereed)
    Abstract [en]

    We present initial results of a measurement system designed for detecting the fluorescence spectrum of individual particles of biological warfare agent (BWA). A compact optical parametric oscillator with intracavity sum-frequency mixing and a commercial Nitrogen gas laser was used as excitation sources to generate 293 nm or 337 nm UV laser irradiation. The pulsed lasers and a photomultiplier tube (PMT) array based spectrometer were triggered by a red laser-diode and a PMT detector that sensed the presence of a particle typical of size 5-20 μm in diameter. The spectral detection part of the system consisted of a grating and a PMT array with 32 channels, which measured fluorescence in the wavelength from 280 nm to 800 nm. The detector system was used to demonstrate the measurement of laser induced fluorescence spectra of individual BWA simulant particles by excitation of single UV laser pulses. The spectrum obtained by averaging spectra from several BWA aerosol simulant particles were found generally similar, but not identical, to the fluorescence spectrum obtained from water solutions containing the same particles dissolved.

  • 13.
    Pasiskevicius, Valdas
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Tiihonen, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Jacobsson, Björn
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Henriksson, Markus
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Hirohashi, Junji
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Canalias, Carlota
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Optical parametric oscillators and amplifiers with periodically poled ferroelectrics2006In: 2nd EPS-QEOD EUROPHOTON CONFERENCE, European Physical Society , 2006Conference paper (Refereed)
  • 14.
    Tiihonen, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Spectral Management in Quasi-Phase-Matched Parametric Devices2006Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Nonlinear optical interaction in quasi-phase-matched structures opens up unique possibilities to build compact and efficient parametric devices such as optical parametric oscillators, generators, and amplifiers with tailored spectral properties. The focus of this thesis is on novel parametric interactions with periodically-poled KTiOPO4 (PPKTP) as the parametric gain medium.

    Optical parametric oscillators (OPOs) are attractive light sources for many applications, particularly in spectroscopy, and plays a central role in this thesis. Special attention is put on simple, yet powerful, spectral-manipulation and bandwidth-narrowing techniques for OPOs. The overall knowledge gained from these studies has been used for device construction of several tunable ultraviolet sources for biological sensing.

    In the case of bandwidth narrowing, the observation of decreasing spectral bandwidth in a noncollinear, idler-resonant OPO, as compared with a signal-resonant one, has been found to be due to the interplay between the material properties and the angular dispersion of PPKTP. To further reduce the bandwidth, we have shown that it is very beneficial to replace the output mirror in an OPO with a bulk Bragg grating. In fact, even close to degeneracy, where the bandwidth is typically wide, this approach is able to decrease the bandwidth drastically.

    Moreover, different OPO cavity designs have been examined in order to spectrally manipulate the resonant waves. By deploying a grating in a ring OPO cavity, it becomes possible to access the resonant wave and spectrally manipulated it in a zero-dispersion arrangement; the filtered wave is subsequently sent back into its own cavity as a seed signal, in a self-seeding arrangement. This particular cavity design decreases the bandwidth close to ~ 1000 times as compare to the free-running mode. An interesting phenomenon arises when two mutually coherent laser beams are used to pump a linear OPO cavity. When the pump beams intersect within the PPKTP crystal, an interference grating is formed and acts as a catalyst for the generation of new spectral sidebands through multiple cascaded four-wave mixing, in the pump, the idler and the signal directions. The spacing of these sidebands is determined geometrically by the incident pump angle, while the signals are continuously tunable over the c-band telecom window (λ ~ 1.5 μm) by rotating the cavity.

    Ultrabroad bandwidths have been generated in an optical parametric generator (OPG) pumped by an amplified picosecond Ti:sapphire laser. In the collinear direction the output spectrum extends over three octaves in the mid-infrared region. This enormously broad spectrum is also Fourier-filtered and subsequently used for narrowband seeding of an optical parametric amplifier (OPA).

    Finally, the spectral range between 285 nm and 340 nm is of importance for detection of biological substances through fluorescence spectroscopy. With this spectral region in mind a practical way to generate a tunable parametric device in the ultraviolet region is presented in the thesis. The developed ultraviolet laser is used for studies of the characteristics of biological particles. The ultraviolet source and the results from these studies, will be utilized in an integrated detection system, a so called early-warning system.

  • 15.
    Tiihonen, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Fragemann, Anna
    KTH, School of Engineering Sciences (SCI), Physics.
    Canalias, Carlota
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Towards Ultrabroad Parametric Gain Bandwidth in Periodically Poled KTiOPO42006In: Advanced solid-state photonics 2006: topical meeting and tabletop exhibit ; January 29 - February 1, 2006, Hyatt Regency Lake Tahoe Resort, Incline Village, Nevada ; conference program and technical digest ; [21st Annual Conference on Advanced Solid-State Photonics], Optical Society of America, 2006Conference paper (Refereed)
    Abstract [en]

    We present Ti:sapphire pumped degenerate parametric generator bandwidths exceeding 130 THz in 8mm-long PPKTP crystals. Collinear and noncollinear interaction schemes are investigated with the goal of obtaining ultrabroad gain bandwidth with zero-angular dispersion.

  • 16.
    Tiihonen, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Two-dimensional quasi-phase-matched multiplecascaded four-wave mixing in periodically poled KTiOPO2006In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 31, no 22, p. 3324-3326Article in journal (Refereed)
    Abstract [en]

    A two-dimensional quasi-phase-matched structure is realized in a noncollinear, nondegenerate periodically poled KTiOPO4 parametric oscillator by utilizing the mutual coherence of two noncollinear pump beams. The mutually coherent pump beams form an interference pattern inside the crystal that is directed perpendicular to the existing quasi-phase-matched grating vector and acts as a parametric gain grating. The cavity itself supports two signal wavelengths around 1550 nm with tunable separation, while the gain grating reduces the operational threshold of the oscillator. Furthermore, with this two-dimensional quasi-phasematched structure, we can demonstrate the generation of new spectral components through multiple chi((2)) : chi((2))-caseaded four-wave mixing processes.

  • 17.
    Tiihonen, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Fragemann, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Canalias, Carlota
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Ultrabroad Gain in an Optical Parametric Generator with periodically poled KTiOPO42006In: Applied physics. B, Lasers and optics (Print), ISSN 0946-2171, E-ISSN 1432-0649, Vol. 85, no 1, p. 73-77Article in journal (Refereed)
    Abstract [en]

    An optical parametric gain bandwidth of 115 THz at full-width half maximum is generated from a picosecond Ti:sapphire pumped degenerate optical parametric generator. This ultrabroad bandwidth could be obtained by first identifying the wavelength where the nonlinear optical material has zero group-velocity dispersion (GVD). By pumping at half this wavelength the degenerate signal-idler pairs can accommodate ultrabroad bandwidths. The explanation for this is that the group velocities of the signal and the idlers are approximately matched and the GVD is small. However, in order to thoroughly investigate the degeneracy region around 1700 nm we fabricated several periodically poled KTiOPO4 (PPKTP) crystals with different periods, and also one periodically poled RbTiOPO4 (PPRTP). Both collinear and noncollinear configurations were employed for broadband parametric generation in this region. It was found that the optimum pump wavelength is in the region between 800 nm to 850 nm for PPKTP, and we could also conclude that a similar performance was found for PPRTP. This work will allow the design of optical parametric devices for generating few-cycle pulses in the spectral region between 1.1 mu m and 3.8 mu m.

  • 18.
    Tiihonen, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Broadly Tunable Picosecond Narrowband pulses in a periodically poled KTiOPO4 parametric amplifier2006In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 14, no 19, p. 8728-8739Article in journal (Refereed)
    Abstract [en]

    A picosecond double-pass periodically poled KTiOPO4 (PPKTP) noncollinear parametric amplifier that delivers tunable and narrowband outputs between 1.1 mu m and 1.65 mu m is reported. The seed source is an ultra-broadband emitting PPKTP collinear parametric generator, which is spectrally narrowed, from a bandwidth of 80 THz to about 0.3 THz, by a Fourier-filtering arrangement. A parametric gain of 70 dB is measured with preserved spectral bandwidth, resulting in a signal energy of 6.5 mu J at a pump energy of 60 mu J from the Ti:sapphire regenerative amplifier. The total energy-budget for the setup is less than 100 mu J with an optical-to-optical efficiency of 12%. This particular system is scalable to even lower pump energies by tighter focusing arrangements

  • 19.
    Tiihonen, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Coherent coupling and cascaded interactions in noncollinear optical parametric oscillator2006Conference paper (Refereed)
    Abstract [en]

    Two-beam pumped noncollinear PPKTP OPO generating two signal waves with tunable spectral separation is demonstrated. The coherent pumping leads to a parametric gain grating which resonantly enhances cascaded sideband generation by the second-order nonlinear interaction.

  • 20.
    Tiihonen, Mikael
    et al.
    KTH, Superseded Departments, Physics.
    Pasiskevicius, Valdas
    KTH, Superseded Departments, Physics.
    Laurell, Fredrik
    KTH, Superseded Departments, Physics.
    Noncollinear double-ring optical parametric oscillators with periodically poled KTiOPO2004In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 12, p. 5526-Article in journal (Refereed)
    Abstract [en]

    A pulsed self-seeded double-ring optical parametric oscillatorrealized with periodically poled KTiOPO4 is demonstrated. When pumpedfrom two opposite directions, the cavity supported two automaticallyaligned, independent, counter-propagating parametric wave pairs whosewavelength could be continuously tuned by varying a single degree offreedom. The tuning range from 1189 nm to 1267 nm has been achieved forthe resonant idler waves. The parametric rings could be cross-seeded byusing a feedback arrangement. Here, Fourier-domain filtering was utilizedto spectrally manipulate the output spectrum of the seeded ring oscillator.Parametric ring oscillator efficiencies of 46 % were achieved.

  • 21.
    Tiihonen, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Physics.
    Spectral and spatial limiting in an idler-resonant PPKTP optical parametric oscillator2005In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 250, no 1-3, p. 207-211Article in journal (Refereed)
    Abstract [en]

    The spectral and spatial properties of a non-collinear signal- and idler-resonant periodically poled KTiOPO4 optical parametric oscillator (OPO) have been investigated. The lower angular dispersion of the idler-resonant OPO allows for generation of up to two-times smaller spectral bandwidths at large non-collinear angles, and at the same time the beam quality improves considerably compared with the signal-resonant case. The overall efficiency reached 67% in both cases.

  • 22.
    Tiihonen, Mikael
    et al.
    KTH, Superseded Departments, Physics.
    Pasiskevicius, Valdas
    KTH, Superseded Departments, Physics.
    Laurell, Fredrik
    KTH, Superseded Departments, Physics.
    Spectral and spatial limiting in idler-resonant optical parametric oscillator with PPKTP2004In: OSA Trends in Optics and Photonics Series: Volume 94, Optical Society of America, 2004, p. 456-460Conference paper (Refereed)
    Abstract [en]

    The spectral and spatial properties of a non-collinear signal- and idler-resonant PPKTP OPO have been investigated. The lower angular dispersion of the idler-resonant OPO allows for generation of up to two-times smaller spectral bandwidths at large non-collinear angles, and at the same time the beam quality improves considerably compared with the signal-resonant case. The overall efficiency reached 67% in both cases.

  • 23.
    Tiihonen, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Tailored UV-laser source for fluorescence spectroscopy of biomolecules2007In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 45, no 4, p. 444-449Article in journal (Refereed)
    Abstract [en]

    A dual-wavelength UV-laser source was developed for biosensing. First, a passively Q-switched diode-pumped Nd:YAG laser was constructed. The astigmatic diode output beam was converted into a homogenous beam profile by utilizing a mode converter. As a result, a frequency-doubling conversion efficiency of 50% was achieved in a periodically poled KTiOPO4. With a repetition rate of 100 Hz, the pulse energies and lengths were 650 mu J and 1.8 ns, respectively, at 532 nm with a M-2 of 1.3. The UV-generation is based on cascaded parametric processes using an intra-cavity sum-frequency mixing scheme in a periodically poled KTiOPO4 parametric oscillator pumped at 532 nm. Here, the wavelengths 293 and 343 nm were generated, with conversion efficiencies of 7% and 6.5%, respectively, in respect to 532 nm. With pulse length 1 ns and an average power above 2.7 mW, the wavelengths were used for fluorescence measurements of nonpathogenic bacteria.

  • 24.
    Tiihonen, Mikael
    et al.
    KTH, Superseded Departments, Physics.
    Pasiskevicius, Valdas
    KTH, Superseded Departments, Physics.
    Laurell, Fredrik
    KTH, Superseded Departments, Physics.
    Wavelength-agile noncollinear optical parametric oscillators with periodically poled KTiOPO42004In: OSA Trends in Optics and Photonics, 2004, p. 471-472Conference paper (Refereed)
    Abstract [en]

    Spectral and spatial properties of the output beams are investigated in noncollinear periodically poled KTiOPO4 OPO. Noncollinear idler-resonant counterpropagating ring parametric oscillators for simple and continuous tunability are realized in a single cavity.

  • 25.
    Tiihonen, Mikael
    et al.
    KTH, Superseded Departments, Physics.
    Pasiskevicius, Valdas
    KTH, Superseded Departments, Physics.
    Laurell, Fredrik
    KTH, Superseded Departments, Physics.
    Hammarström, Per
    Lindgren, Mikael
    A UV laser source for biological and chemical sensing2004In: FREE-SPACE LASER COMMUNICATION AND ACTIVE LASER ILLUMINATION III / [ed] Voelz, DG; Ricklin, JC, BELLINGHAM: SPIE-INT SOC OPTICAL ENGINEERING , 2004, Vol. 5240, p. 127-136Conference paper (Refereed)
    Abstract [en]

    Optical parametric oscillator (OPO) and sum-frequency mixing (SFM) devices are useful tools for constructing ultraviolet (UV) laser sources for fluorescence spectroscopy. Here, a compact UV-laser sources based on frequency conversion of an actively Q-switched Nd:YAG laser is presented. The second harmonic generation from a Nd:YAG laser was utilized as pump radiation for a periodically poled KTiOPO4 nanosecond optical parametric oscillator(1). The OPO-signal and the remaining pump were spatially mode-matched for Type I SFM in a beta-barium borate (BBO) crystal and UV radiation at 293 nm could be generated. This corresponds to a conversion efficiency of 2% with respect to the 532 nm harmonic radiation. The wavelength region accessible with this UV source is useful for chemical and biological sensing. Excitation of tryptophan at 293 nm for detection of fluorescence emission in ovalbumin and transthyretin was demonstrated.

  • 26.
    Tiihonen, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Jonsson, P.
    Kullander, F.
    Tjärnhage, T.
    Nordstrand, M.
    Wästerby, P.
    Lindgren, M.
    Development of Fluorescence-Based LIDAR for Biological Sensing2005Conference paper (Refereed)
  • 27.
    Tiihonen, Mikael
    et al.
    KTH, Superseded Departments, Physics.
    Pasiskevicius, Valdas
    KTH, Superseded Departments, Physics.
    Laurell, Fredrik
    KTH, Superseded Departments, Physics.
    Jonsson, P
    Lindgren, M
    A compact OPO/SFG laser for ultraviolet biological sensing: TECHNOLOGY AND DEVICES2004In: SOLID STATE LASERS XIII: TECHNOLOGY AND DEVICES / [ed] Scheps, R; Hoffman, HJ, BELLINGHAM: SPIE-INT SOC OPTICAL ENGINEERING , 2004, Vol. 5332, p. 134-142Conference paper (Refereed)
    Abstract [en]

    A compact parametric oscillator (OPO) with intracavity sum-frequency generation (SFG) to generate 293 nm UV laser irradiation, was developed. The OPO/SFG device was pumped by a 100 Hz Nd:YAG laser (1064 nm) of own design, including subsequent second harmonic generation (SHG) in an external periodically poled KTiOPO4 (KTP) crystal. The whole system could be used to deliver more than 30 muJ laser irradiation per pulse (100 Hz) at 293 nm. The UV laser light was introduced in an optical fiber attached to a sample compartment allowing detection of fluorescence emission using a commercial spectrometer. Aqueous samples containing biomolecules (ovalbumin) or bacteria spores (Bacillus subtilis) were excited by the UV-light at 293 nm resulting in strong fluorescence emission in the range 325-600 nm.

  • 28.
    Tiihonen, Mikael
    et al.
    KTH, Superseded Departments, Physics.
    Pasiskevicius, Valdas
    KTH, Superseded Departments, Physics.
    Laurell, Fredrik
    KTH, Superseded Departments, Physics.
    Jonsson, P.
    Lindgren, M.
    A novel OPO-SFG laser for biological and chemical sensing2004Conference paper (Refereed)
  • 29.
    Tiihonen, Mikael
    et al.
    KTH, Superseded Departments, Physics.
    Pasiskevicius, Valdas
    KTH, Superseded Departments, Physics.
    Laurell, Fredrik
    KTH, Superseded Departments, Physics.
    Lindgren, M
    A novel UV-laser source for fluorescence excitation of proteins2004In: OPTICALLY BASED BIOLOGICAL AND CHEMICAL SENSING FOR DEFENCE / [ed] Carrano, JC; Zukauskas, A, BELLINGHAM: SPIE-INT SOC OPTICAL ENGINEERING , 2004, Vol. 5617, p. 261-268Conference paper (Refereed)
    Abstract [en]

    A novel, compact and robust UV laser has been developed for laser induced fluorescence spectroscopy of biomolecules in the spectral region from 290 nm to 345 nm. It was based on a frequency-doubled passively Q-switched Nd:YAG laser. emitting at 53 2 nm, which was pumping a periodically poled KTiOPO4 optical parametric oscillator with intra-cavity sum-frequency mixing in a 13130 crystal. The output was generated in two branches in the UV, 293 mn and 343 nm, with pulse widths of 1.8 ns and pulse repetition rate of 100 Hz. These wavelengths were then used for fluorescence experiments of bioagents.

1 - 29 of 29
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