P. Tuomisto

Tampere University of Technology, Tampere, Western Finland, Finland

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Publications (21)21.99 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: We report a passively Q-switched two-component visible laser light source based on frequency conversion. The device consists of a monolithic single transverse mode ridge-waveguide infrared laser diode and a waveguide-type periodically poled magnesium oxide doped lithium niobate crystal for second harmonic light generation. An integrated 45-degree folding mirror and a coupling lens are formed by etching on opposite sides of the monolithic gallium arsenide -based laser diode for coupling the infrared emission into the waveguide-type nonlinear crystal for efficient single pass frequency conversion. Passively Q-switched operation is realized by an integrated electro-absorber section coupled with the in-plane multi-quantum well gain structure. Stable high-repetition rate self-pulsating operation was achieved by reverse-biasing the electro-absorber section and reduced speckle visibility of the second harmonic light was observed when compared to continuous-wave operation of the same laser.
    Proc SPIE 04/2010;
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    ABSTRACT: We report a fast-switching two-component frequency-converted laser with reduced speckle visibility. A bottom-emitting passively Q-switched laser with integrated electroabsorber, folding mirror and coupling lens was successfully applied with a waveguide-type periodically poled magnesium oxide doped lithium niobate crystal to generate second harmonic light at 532 nm. Reduced speckle visibility was demonstrated when operating the laser in self-pulsating mode when compared to continuous-wave operation even when using a nonlinear crystal with narrow acceptance bandwidth of 0.24 nm @ 1064 nm. The spectral width of the infrared light was 0.33 nm in pulsed mode and 0.08 nm in continuous-wave mode resulting in visible light spectral width of 0.12 nm and 0.03 nm in self-pulsating and continuous-wave mode.
    Proc SPIE 02/2010;
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    ABSTRACT: We report the fabrication and characterization of high-quality GaInNAs/GaAs gain mirror as an active media for semiconductor disk lasers emitting at the 12XX nm spectral range. The structure was fabricated by molecular beam epitaxy using a radio frequency plasma source for incorporating the nitrogen. The growth parameters have been optimized to reduce detrimental effects of nitrogen on the emission efficiency. Using the gain mirror, which comprised 10 GaInNAs quantum wells with a relatively low content of nitrogen, we demonstrated semiconductor disk laser with an output power of ∼5 W and a differential efficiency of ∼20%.
    Journal of Crystal Growth 01/2009; · 1.55 Impact Factor
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    ABSTRACT: We report an essential progress towards the development of efficient GaInNAs-based semiconductor disk lasers operating at 1220 nm spectral range. The gain mirrors were fabricated by molecular beam epitaxy using a radio frequency plasma source for incorporating the nitrogen. The typical structure consisted of a 30-pair GaAs/AlAs distributed Bragg reflector and 10 GaInNAs quantum wells with relatively low content of nitrogen. The growth parameters and the composition of the structures have been optimized to reduce the detrimental effect of nitrogen on the emission efficiency. We have achieved a maximum output power of 3.5 W and a differential efficiency of 20%.
    Proc SPIE 05/2008;
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    ABSTRACT: The constraints on dilute-nitride Semiconductor Optical Amplifiers (SOAs) for multi-wavelength amplification have been evaluated. SOAs have been fabricated by angling the facets of a GaInNAs/GaAs edge emitting laser using gas enhanced focused ion beam etching. The original laser has been characterized in terms of its temperature dependence and net modal gain. A full width half maximum (FWHM) of 40nm has been found at 298K. Good temperature stability has also been found with a value of 0.35nm/K for the lasing wavelength. The good temperature stability of the device has been explained in terms of the role that the monomolecular recombination plays in the temperature dependence of the device. The monomolecular recombination has been reported temperature independent having two key effects; reduction of the temperature performance and reduction of the dynamic performance in terms of an increase in the threshold current and a decrease of the high speed potential. Iodine gas enhanced focused ion beam etching (GAE-FIB) has been used for the fabrication of the SOA, the iodine gas increasing the etching rate by a factor of 2.5. The fabrication has been completed in two steps; in the first one the facets have been angled and in the second step a cross-section procedure has been employed for smoothing of the facets. Once the SOA has been fabricated its potential for simultaneous multiple channel amplification has been studied. A flat gain spectrum over a range of 40nm has been obtained. This value and the wavelength range have good agreement with the net modal gain measured in the original laser device. In addition, minimum channel interspacing has been achieved with no wavelength degradation.
    Proc SPIE 05/2008;
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    ABSTRACT: Owing to their good beam quality and high output power, near-infrared semiconductor disk lasers provide an attractive opportunity for visible light generation via frequency conversion. The typical cavity arrangement of a semiconductor disk laser, consisting of a semiconductor multiple quantum well gain mirror and one or more external mirror, offers a convenient configuration for intracavity frequency doubling. Recent progress in the disk laser development has led to demonstrations of multi-watt green-blue-yellow sources. These achievements have been enabled by the possibility to integrate high performance InGaAs/GaAs gain media and Al(Ga)As/GaAs Bragg reflectors operating in the 940-1160 nm wavelength range. In order to achieve ~620 nm red emission, a laser emitting near the fundamental wavelength of 1240 nm is needed. To achieve this spectral range we have developed GaInNAs/GaAs gain mirrors and we have achieved 1 W of output power at 617 nm by frequency doubling in a BBO crystal. This is to our knowledge the highest power reported to date for intracavity doubled disk laser based on dilute nitride gain material.
    Proc SPIE 03/2008;
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    ABSTRACT: The paper presents simulation and experimental studies for the optimization of the ridge profile in ridge waveguide edge-emitting lasers emitting at 980 nm. 2D simulations have been performed, both with in-house developed software and with the commercial simulation package LASTIP, for different etching depths and ridge widths. Several ridge geometries have been fabricated in order to verify experimentally the transverse modal behavior dependence on ridge geometry. The simulation and experimental results are used to derive processing guidelines for achieving stable single-transverse-mode operation in 980 nm ridge waveguide lasers.
    Semiconductor Conference, 2007. CAS 2007. International; 01/2008
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    ABSTRACT: We report on a GaInNAs/GaAs semiconductor disk laser frequency-doubled to produce orange-red radiation. The disk laser operates at a fundamental wavelength of 1224 nm and delivers an output power of 2.68 W in the visible region with an optical-to-optical conversion efficiency of 7.4%. The frequency-converted signal could be launched into a singlemode optical fiber with 70-78% coupling efficiency, demonstrating good beam quality for the visible radiation. Using a Fabry-Pérot glass etalon the emission wavelength could be tuned over an 8 nm spectral range.
    Optics Express 01/2008; 15(26):18345-50. · 3.55 Impact Factor
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    ABSTRACT: Photoluminescence (PL) measurements and in situ reflection high-energy electron diffraction (RHEED) observations were used to optimize GaAs/AlAs multi-quantum-well (MQW) structures grown by molecular beam epitaxy (MBE) under different As fluxes. PL peaks were identified with computer simulations, intensity behavior as a function of temperature, and with previous results in literature. The room temperature PL intensity from our MQW samples first increases with the As flux and then decreases as the flux is increased. Combining our RHEED and PL observations, we propose that an optimum As flux for growth of GaAs/AlAs structures is close to the special As flux at which the GaAs(1 0 0) surface reconstruction changes from (2×4) to (4×2). The reasons for the findings are discussed.
    Applied Surface Science 01/2008; 255(5):2985-2988. · 2.54 Impact Factor
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    Spie Newsroom. 01/2008;
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    ABSTRACT: The need for simultaneous multi-channel transmission in optical communication systems has led to a requirement of semiconductor optical amplifiers (SOAs) with flat gain over a broad range of wavelengths and minimum channel interspacing for the independent and simultaneous amplification of several different laser sources. In addition for ultra-high speed communication with femto-second pulses, composed of a spectrum of wavelengths, simultaneous multi-wavelength amplification is required. The goal of this paper is the modelling, fabrication and characterization of SOAs made from GaInNAs/GaAs quantum-well edge emitting lasers and InAs/GaAs QDot edge-emitting lasers. Both QDots and GaInNAs/GaAs quantum wells (QWs) exhibit broad gain for a range of temperatures and current as measured experimentally.
    Transparent Optical Networks, 2007. ICTON '07. 9th International Conference on; 08/2007
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    ABSTRACT: We report on intracavity frequency-doubling and sum-frequency generation in optically-pumped semiconductor disk lasers. High power second-harmonic red emission from a GaInNAs-based disk laser and aquamarine sum-frequency emission from a dual-wavelength semiconductor disk laser were obtained.
    07/2007;
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    ABSTRACT: We report on frequency doubled GalnNAs-based semiconductor disk laser emitting around 615 nm. The laser gain mirror was fabricated using molecular beam epitaxy.
    Lasers and Electro-Optics, 2007 and the International Quantum Electronics Conference. CLEOE-IQEC 2007. European Conference on; 07/2007
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    ABSTRACT: We report on a high-power GaInNAs/GaAs optically pumped semiconductor disk laser operating at a wavelength of 1240 nm. The laser structure consisted of 12 dilute nitride (GaInNAs) quantum wells placed on top of a GaAs/AlAs distributed Bragg reflector, the whole structure being grown by molecular beam epitaxy. A diamond heat spreader was bonded onto the sample for improved heat dissipation. When cooled down to 8°C, the laser produced continuous-wave output power up to 1.46 W in the TEM00 mode, demonstrating the potential of dilute nitrides for high-power disk laser applications.
    New Journal of Physics 05/2007; 9(5):140. · 4.06 Impact Factor
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    ABSTRACT: We report on an optically-pumped intracavity frequency doubled GaInNAs/GaAs -based semiconductor disk laser emitting around 615 nm. The laser operates at fundamental wavelength of 1230 nm and incorporates a BBO crystal for light conversion to the red wavelength. Maximum output power of 172 mW at 615 nm was achieved from a single output. Combined power from two outputs was 320 mW. The wavelength of visible emission could be tuned by 4.5 nm using a thin glass etalon inside the cavity.
    Optics Express 04/2007; 15(6):3224-9. · 3.55 Impact Factor
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    ABSTRACT: A 1234 nm GalnNAs/GaAs optically-pumped semiconductor disk laser utilising an intracavity BBO (beta barium borate) crystal for nonlinear frequency conversion is reported. 1 W of power at 617 nm has been achieved.
    Electronics Letters 02/2007; · 1.04 Impact Factor
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    ABSTRACT: We discuss a new method to shape the temporal response of saturable absorption in semiconductors. In particular, we investigate the possibility to control independently the absorption recovery time of each quantum-well forming the semiconductor absorber. The recovery time is tailored by irradiation with nitrogen ions produced by an RF-plasma source. The irradiation is performed in-situ as one step of the epitaxial growth process; the quantum-wells are individually exposed to a flux of N-ions after they are grown. The amount of non-radiative recombination centers within the quantum-wells is strongly related to the time interval during which the N-ions flux is active and to the thickness of the semiconductor layer grown on top of each quantum-well before the irradiation is performed. We apply this method to fabricate fast semiconductor saturable absorbers operating in the 1-mum wavelength range. The absorption recovery time could be changed from 300 ps to 10 ps without degradation of the nonlinear optical response. The practicality of the design is finally proved by using the semiconductor saturable absorbers for mode-locking Yb-doped fiber lasers.
    Proc SPIE 01/2007;
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    ABSTRACT: The constraints on dilute-nitride Semiconductor Optical Amplifiers (SOAs) for multi-channel amplification have been evaluated. The SOA has been fabricated angling the facets of a GalnNAs/GaAs edge emitting laser using gas enhanced focused ion beam etching.
    01/2007;
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    ABSTRACT: We demonstrate a ring cavity ytterbium fiber laser mode-locked with a semiconductor saturable absorber used in transmission. The resonant cavity-enhanced nonlinear response corresponding to the low-loss transmission state enables a robust self-starting mode-locking. Such a transfer function is opposite to that of the resonant absorber operating in the reflection mode, where the highest modulation depth matches the high-loss state. The device ensures ultrashort pulse operation with the wavelength self-adjusted to the optimal value corresponding to the low-loss state of the laser cavity. When using a saturable absorber etalon in transmission mode, the mode-locking mechanism is also highly tolerant to the total cavity dispersion
    IEEE Photonics Technology Letters 11/2006; · 2.04 Impact Factor
  • J. Konttinen, P. Tuomisto, M. Guina, M. Pessa
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    ABSTRACT: The GaInNAs/GaAs semiconductor heterostructures have emerged as promising alternatives to InP-based compound semiconductors for the fabrication of 1.3-mum METRO and LAN telecommunications lasers. We shall review the recent advances made in the field of the GaInNAs technology. An emphasis is put on the development of low-threshold double-quantum-well (DQW) and triple-quantum-well (TQW) ridge waveguide lasers (RWG) grown by molecular beam epitaxy. A record slope efficiency of 0.28 W/A and a low threshold current density of 278 A/cm<sup>2</sup>/QW are demonstrated in this paper for the TQW single-mode lasers. We shall also discuss the first measurements of electron-spin relaxation in dilute nitride quantum-wells. Excitation of spin-polarized electrons is potentially attractive for implementing all-optical polarization switches in a broad wavelength range
    Transparent Optical Networks, 2006 International Conference on; 07/2006

Publication Stats

58 Citations
21.99 Total Impact Points

Institutions

  • 2006–2009
    • Tampere University of Technology
      • Optoelektroniikan tutkimuskeskus
      Tampere, Western Finland, Finland
  • 2007
    • University of Bristol
      • Department of Electrical and Electronic Engineering
      Bristol, England, United Kingdom