Showing papers on "Tunable laser published in 2009"
TL;DR: In this paper, a calibration-free wavelength-modulation spectroscopy with second harmonic detection (WMS-2f) for measurements of gas temperature and concentration in harsh environments is presented.
Abstract: We present a practical implementation of calibration-free wavelength-modulation spectroscopy with second harmonic detection (WMS-2f) for measurements of gas temperature and concentration in harsh environments. The method is applicable to measurements using lasers with synchronous wavelength and intensity modulation (such as injection current-tuned diode lasers). The key factors that enable measurements without the on-site calibration normally associated with WMS are (1) normalization of the WMS-2f signal by the first harmonic (1f) signal to account for laser intensity, and (2) the inclusion of laser-specific tuning characteristics in the spectral-absorption model that is used to compare with measured 1f-normalized, WMS-2f signals to infer gas properties. The uncertainties associated with the calibration-free WMS method are discussed, with particular emphasis on the influence of pressure and optical depth on the WMS signals. Many of these uncertainties are also applicable to calibrated WMS measurements. An example experimental setup that combines six tunable diode laser sources between 1.3 and 2.0 mum into one probe beam for measurements of temperature, H(2)O, and CO(2) is shown. A hybrid combination of wavelength and frequency demultiplexing is used to distinguish among the laser signals, and the optimal set of laser-modulation waveforms is presented. The system is demonstrated in the harsh environment of a ground-test scramjet combustor. A comparison of direct absorption and 1f-normalized, WMS-2f shows a factor of 4 increase in signal-to-noise ratio with the WMS technique for measurements of CO(2) in the supersonic flow. Multidimensional computational fluid-dynamics (CFD) calculations are compared with measurements of temperature and H(2)O using a simple method that accounts for the influence of line-of-sight (LOS) nonuniformity on the absorption measurements. The comparisons show the ability of the LOS calibration-free technique to gain useful information about multidimensional CFD models.
446 citations
TL;DR: A good qualitative agreement is demonstrated between experimental results and numerical modeling based on modified nonlinear Schrödinger equations in the noise-like pulse generation regime.
Abstract: We observed generation of stable picoseconds pulse train and double-scale optical lumps with picosecond envelope and femtosecond noise-like oscillations in the same Yb-doped fiber laser with all-positive-dispersion cavity mode-locked due to the effect of non-linear polarization evolution. In the noise-like pulse generation regime the auto-correlation function has a non-usual double (femto- and picosecond) scale shape. We discuss mechanisms of laser switching between two operation regimes and demonstrate a good qualitative agreement between experimental results and numerical modeling based on modified nonlinear Schrodinger equations.
243 citations
TL;DR: This review describes experiments in which tunable infrared lasers have been used to irradiate ions in Penning traps, and the ionic systems examined have ranged from small hydrocarbons to multiply charged proteins, and they are discussed in approximate order of increasing complexity.
Abstract: The ability of Paul and Penning traps to contain ions for time periods ranging from milliseconds to minutes allows the trapped ions to be subjected to laser irradiation for extended lengths of time. In this way, relatively low-powered tunable infrared lasers can be used to induce ion fragmentation when a sufficient number of infrared photons are absorbed, a process known as infrared multiple photon dissociation (IRMPD). If ion fragmentation is monitored as a function of laser wavelength, a photodissociation action spectrum can be obtained. The development of widely tunable infrared laser sources, in particular free electron lasers (FELs) and optical parametric oscillators/amplifiers (OPO/As), now allows spectra of trapped ions to be obtained for the entire "chemically relevant" infrared spectral region. This review describes experiments in which tunable infrared lasers have been used to irradiate ions in Penning traps. Early studies which utilized tunable carbon dioxide lasers with a limited output range are first reviewed. More recent studies with either FEL or OPO/A irradiation sources are then covered. The ionic systems examined have ranged from small hydrocarbons to multiply charged proteins, and they are discussed in approximate order of increasing complexity.
240 citations
TL;DR: By controlling local substrate temperature in a chemical vapor deposition system, the nanowire chip provides a spatially continuously tunable laser with a superbroad wavelength tuning range, unmatched by any other available semiconductor-based technology.
Abstract: By controlling local substrate temperature in a chemical vapor deposition system, we have successfully achieved spatial composition grading covering the complete composition range of ternary alloy CdSSe nanowires on a single substrate of 1.2 cm in length. Spatial photoluminescence scan along the substrate length shows peak wavelength changes continuously from ∼500 to ∼700 nm. Furthermore, we show that under strong optical pumping, every spot along the substrate length displays lasing behavior. Thus our nanowire chip provides a spatially continuously tunable laser with a superbroad wavelength tuning range, unmatched by any other available semiconductor-based technology.
212 citations
TL;DR: In this paper, the effect of optically pumped lasing in a'super yellow' film cast onto a gate dielectric and gate conducting electrode was investigated, and it was observed during the study that light-emitting field-effect-transistor (LEFET) architecture with a distributed feedback (DFB) resonator structure nanoimprinted into the gain medium helped to achieve an electrically pumped plastic laser.
Abstract: A study was conducted to investigate the effect of optically pumped lasing in a 'super yellow' film cast onto a gate dielectric and gate conducting electrode. It was observed during the study that light-emitting field-effect-transistor (LEFET) architecture with a distributed feedback (DFB) resonator structure nanoimprinted into the gain medium helped to achieve an electrically pumped plastic laser. Nanoimprint lithography was applied to obtain 1D and 2D DFB grating resonator structures in multilayer films. The study showed that the 2D DFB laser provided a lower lasing threshold compare to 1D DFB laser under same conditions. The nanoimprinted 2D DFB laser showed a lasing threshold of 32nJ/pulse and slope efficiency of 1.2%. The 1D grating provided a high degree of chain orientation for the organic semiconducting polymers in the source-drain channel.
143 citations
TL;DR: A transportable prototype Faraday rotation spectroscopic system based on a tunable external cavity quantum cascade laser has been developed for ultrasensitive detection of nitric oxide (NO) and results of continuous, unattended monitoring of atmospheric NO concentration levels are reported.
Abstract: A transportable prototype Faraday rotation spectroscopic system based on a tunable external cavity quantum cascade laser has been developed for ultrasensitive detection of nitric oxide (NO). A broadly tunable laser source allows targeting the optimum Q3/2(3/2) molecular transition at 1875.81 cm−1 of the NO fundamental band. For an active optical path of 44 cm and 1-s lock-in time constant minimum NO detection limits (1σ) of 4.3 parts per billion by volume (ppbv) and 0.38 ppbv are obtained by using a thermoelectrically cooled mercury–cadmium–telluride photodetector and liquid nitrogen-cooled indium–antimonide photodetector, respectively. Laboratory performance evaluation and results of continuous, unattended monitoring of atmospheric NO concentration levels are reported.
142 citations
TL;DR: The effect of chromatic dispersion on coherence length and noise of Fourier Domain Mode Locked (FDML) lasers and a simple model is developed providing a connection between timing, photon cavity lifetime and characteristic time constant of the filter.
Abstract: We report on the effect of chromatic dispersion on coherence length and noise of Fourier Domain Mode Locked (FDML) lasers. An FDML laser with a sweep range of 100nm around 1550nm has been investigated. Cavity configurations with and without dispersion compensation have been analyzed using different widths of the intra-cavity optical band-pass filter. The measurements are compared to non-FDML wavelength swept laser sources. Based on these observations, a simple model is developed providing a connection between timing, photon cavity lifetime and characteristic time constant of the filter. In an optimized configuration, an instantaneous laser linewidth of 20pm is observed, corresponding to a 10× narrowing compared to the intra-cavity optical band-pass filter. A relative intensity noise of -133dBc/Hz or 0.2% at 100MHz detection bandwidth during sweep operation is observed. For optimum operation, the filter drive frequency has to be set within 2ppm or 120mHz at 51kHz.
124 citations
TL;DR: A wavelength-swept fiber laser with high speed and wide tuning range, and its application to fiber sensors is reported, based on the dispersion tuning technique, which does not require any optical tunable filter in the laser cavity.
Abstract: We report a wavelength-swept fiber laser with high speed and wide tuning range, and its application to fiber sensors. The laser is based on the dispersion tuning technique, which does not require any optical tunable filter in the laser cavity. By directly modulating the semiconductor amplifier and adjusting the dispersion in the cavity, a wide wavelength tuning range of 178.7 nm and a fast tuning rate of over 200 kHz are obtained. The wavelength-swept laser source is applied to a dynamic fiber Bragg grating sensing system. Dynamic measurement of a 150 Hz sinusoidal strain is demonstrated with a measuring speed as fast as 40 kHz.
114 citations
TL;DR: The continuous tuning of the CW THz emission from Fe(+)-implanted InGaAs photomixers is successfully demonstrated using the monolithic dual-mode laser as the excitation source.
Abstract: We report on a monolithic dual-mode semiconductor laser operating in the 1550-nm range as a compact optical beat source for tunable continuous-wave (CW) terahertz (THz) generation. It consists of two distributed feedback (DFB) laser sections and one phase section between them. Each wavelength of the two modes can be independently tuned by adjusting currents in micro-heaters which are fabricated on the top of the each DFB section. The continuous tuning of the CW THz emission from Fe+-implanted InGaAs photomixers is successfully demonstrated using our dual-mode laser as the excitation source. The CW THz frequency is continuously tuned from 0.17 to 0.49 THz.
114 citations
NEC1
TL;DR: A wavelength tunable laser with an SOA and external double micro-ring resonator, which is fabricated with silicon photonic-wire waveguides, is demonstrated, and is the first wavelength Tunable laser fabricated with Silicon photonic technology.
Abstract: A wavelength tunable laser with an SOA and external double micro-ring resonator, which is fabricated with silicon photonic-wire waveguides, is demonstrated. To date, it is the first wavelength tunable laser fabricated with silicon photonic technology. The device is ultra compact, and its external resonator footprint is 700 x 450 microm, which is about 1/25 that of conventional tunable lasers fabricated with SiON waveguides. The silicon resonator shows a wide tuning range covering the C or L bands for DWDM optical communication. We obtained a maximum tuning span of 38 nm at a tuning power consumption of 26 mW, which is about 1/8 that of SiON-type resonators.
104 citations
TL;DR: Continuous wave laser operation with a tunable range of over 300 nm in the visible and near-infrared regions is demonstrated using a single 9-cm Pr(3+)-doped ZBLAN fiber pumped by a GaN laser.
Abstract: We demonstrated continuous wave laser operation with a tunable range of over 300 nm in the visible and near-infrared regions (479–497, 515–548, 597–737, 849-960 nm) using a single 9-cm Pr3+-doped ZBLAN fiber pumped by a GaN laser The total tunable range was 6469 cm−1, which is wider than that of conventional Ti:sapphire lasers
TL;DR: This paper reports the first experimental realization of distributed feedback (DFB) semiconductor lasers based on reconstruction-equivalent-chirp (REC) technology, which shows a potential for the REC technology in combination with the photonic integrated circuits (PIC) technology to be a possible method for monolithic integration.
Abstract: In this paper we report, to the best of our knowledge, the first experimental realization of distributed feedback (DFB) semiconductor lasers based on reconstruction-equivalent-chirp (REC) technology. Lasers with different lasing wavelengths are achieved simultaneously on one chip, which shows a potential for the REC technology in combination with the photonic integrated circuits (PIC) technology to be a possible method for monolithic integration, in that its fabrication is as powerful as electron beam technology and the cost and time-consuming are almost the same as standard holographic technology.
TL;DR: In this paper, a double-ring-resonator-coupled tunable laser with series-connected microring resonators is described, achieving a tuning range of 50 nm with injection current of less than 5.2 mA.
Abstract: We describe widely tunable lasers incorporating microring resonators. By using a double-ring-resonator-coupled filter, a wide wavelength tuning range is achieved with a low tuning current. A double-ring-resonator-coupled tunable laser has series-connected microring resonators in the laser cavity. A tuning range of 50 nm is achieved with injection current of less than 5.2 mA. This low injection current reduces the frequency drift caused by thermal transients to less than 5 GHz. We also describe an integrated filtered feedback tunable laser consisting of a Fabry-Perot (FP) laser and integrated filtered feedback sections. In this device, the filter section is removed from the laser cavity. The device exhibits a 24-nm tuning range with a side-mode suppression ratio of 50 dB. The frequency drift is less than 1 GHz because the longitudinal mode of the laser is mainly determined by the FP laser section. We have also developed a filter-free widely tunable wavelength converter by monolithically integrating a tunable laser and a wavelength converter based on a semiconductor optical amplifier. Wavelength conversion for a 10-Gb/s nonreturn-to-zero signal is also demonstrated, tunable over a 40-nm range.
TL;DR: In this paper, a density-matrix based theory of transport and lasing in quantum-cascade lasers is proposed, which reveals that large disparity between luminescent linewidth and broadening of the tunneling transition changes the design guidelines to favor strong coupling between injector and upper laser level.
Abstract: A density-matrix based theory of transport and lasing in quantum-cascade lasers reveals that large disparity between luminescent linewidth and broadening of the tunneling transition changes the design guidelines to favor strong coupling between injector and upper laser level. This conclusion is supported by the experimental evidence.
TL;DR: In this article, a corrugated pattern etched into both sidewalls of the 6- and 9-μm wide ridges serves to suppress higher-order lateral modes by increasing their loss, and also provides a fourth-order distributed-feedback grating for longitudinal mode selection.
Abstract: We report interband cascade lasers operating in a single spectral mode (λ≈3.6 μm) at −5–30 °C. A corrugated pattern etched into both sidewalls of the 6- and 9-μm-wide ridges serves to suppress higher-order lateral modes by increasing their loss, and also provides a fourth-order distributed-feedback grating for longitudinal mode selection. Despite the grating’s weak coupling strength, the 9 μm ridge produced up to 12 mW per facet of single-mode cw output power at 25 °C, with a side-mode suppression ratio of >30 dB.
TL;DR: A new method for monitoring the nonlinearities perturbing the optical frequency sweep in high speed tunable laser sources is presented, which allowed to drastically reduce the effects of nonlinear sweep, resulting to a spatial resolution enhancement of 30 times.
Abstract: A new method for monitoring the nonlinearities perturbing the optical frequency sweep in high speed tunable laser sources is presented. The swept-frequency monitoring system comprises a Mach-Zehnder interferometer and simple signal processing steps. It has been implemented in a coherent optical frequency domain reflectometer which allowed to drastically reduce the effects of nonlinear sweep, resulting to a spatial resolution enhancement of 30 times.
TL;DR: The pump laser is a high power tapered laser with a distributed Bragg reflector etched in the ridge section of the laser to provide wavelength selectivity and a conversion efficiency of 18.5 % was achieved in the experiments.
Abstract: More than 1.5 W of green light at 531 nm is generated by single-pass second harmonic generation in periodically poled MgO:LiNbO3. The pump laser is a high power tapered laser with a distributed Bragg reflector etched in the ridge section of the laser to provide wavelength selectivity. The output power of the single-frequency tapered laser is 9.3 W in continuous wave operation. A conversion efficiency of 18.5 % was achieved in the experiments.
TL;DR: In this paper, a quantum cascade laser structure based on three-phonon-resonance design is proposed and demonstrated, and a 3 mm long, 12 μm wide buried-heterostructure device without a high-reflection (HR) coating exhibited continuous wave output power of as high as 65 mW from a single facet at 300 K.
Abstract: A quantum cascade laser structure based on three-phonon-resonance design is proposed and demonstrated. Devices, emitting at a wavelength of 9 μm, processed into buried ridge waveguide structures with a 3 mm long, 16 μm wide cavity and a high-reflection (HR) coating have shown peak output powers of 1.2 W, slope efficiencies of 1 W/A, threshold current densities of 1.1 kA/cm2, and high wall-plug efficiency of 6% at 300 K. A 3 mm long, 12 μm wide buried-heterostructure device without a HR coating exhibited continuous wave output power of as high as 65 mW from a single facet at 300 K.
TL;DR: To demonstrate the applicability of wavelength beam combined DFB-QCL arrays for remote sensing, the absorption spectrum of isopropanol at a distance of 6 m from the laser array was obtained.
Abstract: Wavelength beam combining was used to co-propagate beams from 28 elements in an array of distributed-feedback quantum cascade lasers (DFB-QCLs). The beam-quality product of the array, defined as the product of near-field spot size and far-field divergence for the entire array, was improved by a factor of 21 by using wavelength beam combining. To demonstrate the applicability of wavelength beam combined DFB-QCL arrays for remote sensing, we obtained the absorption spectrum of isopropanol at a distance of 6 m from the laser array.
TL;DR: In this paper, the main design considerations for efficient operation of hybrid laser based on Er:YAG in both continuous-wave (CW) and pulsed modes of operation are discussed. And the potential for further increase in output power and improvement in overall performance in CW and Q-switched modes of operations is discussed.
Abstract: Hybrid fiber-laser-pumped solid-state lasers exploit high-power cladding-pumped fiber lasers for direct (in-band) pumping of a crystal-based solid-state laser to reduce heating in the laser crystal, and hence allow scaling to higher power in both continuous-wave (CW) and pulsed modes of operation. In this paper, we briefly review the attractions of the hybrid laser approach for generation of output in the ~ 1.6 mum wavelength regime and consider the main design considerations for efficient operation of hybrid lasers based on Er:YAG in both CW and pulsed modes of operation. Examples of hybrid Er:YAG lasers, pumped by Er,Yb codoped fiber lasers at 1532 nm, with CW output powers up to 60 W at 1645 nm and 31 W at 1617 nm and slope efficiencies of 80% and 47% with respect to incident pump power, respectively, are described. In Q-switched mode of operation, pulse energies up to 30.5 mJ were obtained, limited by coating damage. Finally, the prospects for further increase in output power and improvement in overall performance in CW and Q-switched modes of operation will be discussed.
TL;DR: The first theoretical model of Fourier domain mode locking operation in a moving spectral reference frame is presented, enabling efficient numerical treatment, despite the broad laser spectrum and the extremely long cavity.
Abstract: The first theoretical model of Fourier domain mode locking operation is presented. A specially tailored dynamic equation in a moving spectral reference frame is derived, enabling efficient numerical treatment, despite the broad laser spectrum and the extremely long cavity. The excellent agreement of the presented theory with experiment over a wide range of operation parameters enables a quantitative assessment of the relevant physical effects, such as the spectral loss modulation and gain saturation dynamics, amplified spontaneous emission, linewidth enhancement, and self-phase modulation.
TL;DR: A diode-pumped high-power continuous-wave laser at 912 nm based on the quasi-three-level (4)F(3/2)-->(4)4I(9/2) transition in Nd:GdVO(4) crystal is presented.
Abstract: We present a diode-pumped high-power continuous-wave (cw) laser at 912 nm based on the quasi-three-level 4F3/2→4I9/2 transition in Nd:GdVO4 crystal. By using a 5-mm-long conventional bulk crystal with 0.2at.% Nd3+-doped concentration, the maximum output power of 12.0 W is obtained, with a slope efficiency of 29.3%. To the best of our knowledge, this is the highest output at 912 nm generated by diode-pumped Nd:GdVO4 lasers. Furthermore, 3.2 W 456 nm deep-blue light is acquired by frequency doubling, resulting in an optical-to-optical efficiency of 8.0%. The short-term power instability of the blue laser is less than 3%.
TL;DR: In this paper, a metal layer is deposited on top of the semiconductor microdisk, the radius of which is systematically varied to enable mode hybridization between surface-plasmon and dielectric modes, and the anticrossing behavior of the two cavity modes is experimentally observed via photoluminescence spectroscopy and optically pumped lasing action at a wavelength of λ ~ 1.3 µm.
Abstract: Hybridization of surface-plasmon and dielectric waveguide whispering-gallery modes are demonstrated in a semiconductor microdisk laser cavity of subwavelength proportions. A metal layer is deposited on top of the semiconductor microdisk, the radius of which is systematically varied to enable mode hybridization between surface-plasmon and dielectric modes. The anticrossing behavior of the two cavity mode types is experimentally observed via photoluminescence spectroscopy and optically pumped lasing action at a wavelength of λ ~1.3 µm is achieved at room temperature.
TL;DR: In this paper, a low-order distributed feedback (DFB) optofluidic dye laser with reduced threshold was demonstrated using replica molding with two masters, and the second order DFB dye laser exhibited the lowest pump threshold of 78 nJ/pulse.
Abstract: We report the demonstration of low order distributed feedback (DFB) optofluidic dye lasers with reduced threshold. The laser chips were realized in polydimethylsiloxane using replica molding with two masters. A comparison between first, second, and third order DFB dye lasers was performed, while the second order DFB dye laser exhibited the lowest pump threshold of 78 nJ/pulse. Compared to previous reports on higher order Bragg grating structures, the pump threshold in this work is approximately 30-fold lower than the state of the art due to the reduction in the cavity losses and the more efficient pumping configuration.
TL;DR: In this paper, a discrete mode (DM) laser was proposed, which is basically a ridge waveguide Fabry-Perot (FP) laser whose wavelength spectra has been modified to obtain a single mode operation.
Abstract: The authors present a novel, low cost laser transmitter for telecommunication systems. This device, called discrete mode (DM) laser, is basically a ridge waveguide Fabry-Perot (FP) laser, whose wavelength spectra has been modified to obtain a single mode operation. This is achieved by perturbing the effective refractive index of the guided mode along very small sections of the laser cavity, by etching features into the ridge waveguide. Suitable positioning of these interfaces allows the mirror loss spectrum of an FP laser to be manipulated in order to achieve single longitudinal mode emission. The waveguide structure requires only a single growth stage and uses optical lithography to realise the ridge. In addition, the fabrication process is re-growth free. Despite this simple and low cost fabrication process, the DM lasers portray many advantages over the distributed feedback and distributed Bragg reflector lasers, such as very high side mode suppression ratio, stable operation over a large temperature range, narrow linewidth and low sensitivity to optical feedback.
TL;DR: The cubic-quintic Ginzburg-Landau equation can serve to qualitatively explain the experimental observations ofissipative soliton evolution in passively mode-locked fiber lasers with ultra-large net-normal-dispersion.
Abstract: Dissipative soliton (DS) evolution in passively mode-locked fiber lasers with ultra-large net-normal-dispersion (as large as 1 ps(2)) is investigated. The proposed DS laser operates on three statuses with respect to the pump power. The DS laser works on a status that is similar to an all-normal-dispersion laser when the pump power is low, whereas it creates a new type of pulses exhibited as the trapezoid-spectrum profile when the pump power is large. The laser cavity emits the unstable pulses between the above two statuses. The cubic-quintic Ginzburg-Landau equation can serve to qualitatively explain our experimental observations.
TL;DR: What the authors believe to be the first demonstration of an edge-emitting Bragg reflection waveguide laser is reported, using InGaAs quantum wells emitting at 980 nm, with Al(x)Ga(1-x)As core and claddings.
Abstract: What we believe to be the first demonstration of an edge-emitting Bragg reflection waveguide laser is reported. The laser utilized InGaAs quantum wells emitting at 980 nm, with AlxGa1−xAs core and claddings. The lasing mode is centered in a low-index core with a width of 700 nm, hence providing a large mode volume with strong discrimination against any modes other than the fundamental photonic bandgap mode. Single-transverse mode operation is observed with thresholds as low as 157 A/cm2. The propagation losses of the mode were measured for the first time and found to be 11.4 cm−1.
TL;DR: This work demonstrates, for the first time, 10 W, Er-fiber laser pumped, pure CW, thermally diffusion doped, polycrystalline Cr(2+):ZnS laser operating at 2380 nm with maximum output power of 7.4 W.
Abstract: We demonstrate, for the first time, 10 W, Er-fiber laser pumped, pure CW, thermally diffusion doped, polycrystalline Cr(2+):ZnS laser operating at 2380 nm. We also show Littrow-grating, "single-knob", wavelength tuning of the laser spanning 1940-2780 nm spectral range with the maximum output power of 7.4 W near the central wavelength of 2400 nm and above 2 W over 1970-2760 nm wavelength range. The laser performs with 40% real optical- and 43% slope efficiency, and shows no output power roll-off up to the highest available incident pump power of 27 W.
TL;DR: In this paper, a sequence of partially reflective slots etched into an active ridge waveguide of a 1.5 mum laser structure is found to provide sufficient reflection for lasing, and two such active mirrors together with an active central section are combined in a Vernier configuration to demonstrate a tunable laser exhibiting 11 discrete modes over a 30 nm tuning range with mode spacing around 400 GHz and side-mode suppression ratio larger than 30 dB.
Abstract: A sequence of partially reflective slots etched into an active ridge waveguide of a 1.5 mum laser structure is found to provide sufficient reflection for lasing. Mirrors based on these reflectors have strong spectral dependence. Two such active mirrors together with an active central section are combined in a Vernier configuration to demonstrate a tunable laser exhibiting 11 discrete modes over a 30 nm tuning range with mode spacing around 400 GHz and side-mode suppression ratio larger than 30 dB. The individual modes can be continuously tuned by up to 1.1 nm by carrier injection and by over 2 nm using thermal effects. These mirrors are suitable as a platform for integration of other optical functions with the laser. This is demonstrated by monolithically integrating a semiconductor optical amplifier with the laser resulting in a maximum channel power of 14.2 dBm from the discrete modes.
TL;DR: In this paper, the effect of external optical feedback on 17 GHz passively mode-locked two-section lasers based on InAs/InP quantum dashes emitting at 1.58 µm was investigated.
Abstract: We report on a systematic investigation of the effect of external optical feedback on 17 GHz passively mode-locked two-section lasers based on InAs/InP quantum dashes emitting at 1.58 μm. Narrowing of mode-beating linewidth down to a record value of ∼500 Hz is demonstrated over a large operating range.