Homogeneously broadened optical amplifier noise

Skip to Main Content. A not-for-profit organization, IEEE is the world's largest technical professional organization dedicated to advancing technology for the benefit of humanity. Use of this web site signifies your agreement to the terms and conditions. The model is based on solutions to differential equations which describe the steady-state amplification of the modes for unidirectional propagation through a homogeneously broadened gain medium. The approximate nature of the laser model is due to the neglect of the counter propagating intensity. This beam had to be neglected in order to find analytic solutions to the coupled, non-linear differential equations.

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• Optical amplifier
• Advance in Microwave Photonics
• Stimulated Brillouin Review: Invented 50 Years Ago and Applied Today
• Erbium-Doped Fiber Amplifiers (EDFA)
• Electron-Ion Coupling Mechanism to Construct Stable Output Performance Nanogenerator
• Homogeneous Broadening
• Mechanical and Aerospace Engineering (MAE)
• Ahead of Print / Just Accepted
• CHAPTER 3---- Laser Amplifiers 2015-7-2Fundamentals of Photonics 1 Chapter 3 Laser Amplifiers.
• Gain Saturation in Optical Fiber Laser Amplifiers

WATCH RELATED VIDEO: Optical Amplification

Optical amplifier

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Find more information on the Altmetric Attention Score and how the score is calculated. Visible-light communications VLCs based on white light-emitting diodes LEDs are emerging as a low-cost and energy-efficient alternative solution to wireless communications. We report the fabrication and characterization of planar and channel waveguides based on a blue-emitting polyfluorene conjugated polyelectrolyte, namely, poly[9,9-bis 4-sulfonylbutoxyphenyl fluorene-2,7-diyl- alt -1,4-phenylene] PBS-PFP incorporated into diureasil organic—inorganic hybrids for optical amplification in VLC.

This value is among the best figures of merit known for polymeric materials with additional advantages added by the diureasil hybrid host, namely, mechanical flexibility, thermal stability, and low insertion losses due to the nearly null refractive index contrast between the optical fiber and the amplification device, establishing the proposed approach as a promising cost-effective solution for optical amplification in VLCs.

Figure 1. Figure 2. The scale bars represent 1 cm. M and F denote monolith and film samples, respectively. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Scheme of the experimental setup used to measure the net gain with a modulated optical signal for the two pumping strategies external perpendicular or co-propagating. More details on the sample synthesis and processing, spectroscopic ellipsometry analysis, and optical gain measurements PDF.

Such files may be downloaded by article for research use if there is a public use license linked to the relevant article, that license may permit other uses. The authors thank Dr. Ana-Teresa Marques and Prof. More by Ana Bastos. More by Barry McKenna. More by Paulo S. More by Rachel C. More by Rute A.

Cite this: ACS Omega , 3 , 10 , — ACS AuthorChoice. Article Views Altmetric -. Citations Abstract High Resolution Image. Recent advances in light-emitting diode LED technology have created a new generation of energy-efficient light sources that look set to revolutionize the indoor lighting market.

Despite the ease of processability, the simultaneous control of both the morphology and electronic properties remains a significant challenge for conjugated polymers. Optical loss mechanisms, such as singlet-state annihilation and charge generation, are mediated by interchain coupling, 21 which becomes exacerbated upon transfer to the solid state. Strategies for the control of intermolecular interactions, while maintaining or even enhancing the optical properties in the solid-state are thus highly desirable.

We have recently shown that incorporation of CPs into organosilica hybrid polymers known as diureasils Figure 1 is an effective approach to minimize interchain interactions leading to highly emissive solid-state materials. High Resolution Image. Inspired by these results, we postulated that the combination of a short-lived CP, coupled with the waveguide characteristics of the diureasil, could deliver a fast-response optical amplifier, suitable for VLC. To minimize spectral losses, we chose to use the blue-emitting poly[9,9-bis 4-sulfonylbutoxyphenyl fluorene-2,7-diyl- alt -1,4-phenylene] PBS-PFP, Figure 1 , which exhibits good spectral overlap with the diureasil and shows thermally assisted population of radiative trap sites.

Moreover, we exploit the intrinsic self-patternability of diureasils to fabricate optical architectures within the CP—diureasil composites using direct UV laser writing on the surface. Results and Discussion. Organic—inorganic hybrid materials incorporating PBS-PFP have been synthesized by the versatile sol—gel methodology at ambient temperature.

Moreover, upon increasing the PBS-PFP concentration, a new band peaking at nm appears, which is ascribed to the polyfluorene absorption. Upon excitation at nm, PBS-PFP diureasil monoliths reveal a structured emission band between and nm Figure 2 c , which is characteristic of the vibronic relaxation of the polyfluorene excited singlet state.

Comparing the emission spectra of the samples processed as monoliths with those in films Figure 2 d , while those for the low-concentrated film PBSF resemble the emission spectra of the monoliths, the emission spectra of the more concentrated films PBS4-F and PBSF are shifted to the blue region, revealing additional variations in the relative intensity of the vibronic progression components.

The contribution of both the dU and PBS-PFP excited states to the observed blue emission is also inferred from the excitation spectra monitored around nm Figure 2 e,f.

The spectra are dominated by a band between and nm, assigned to overlapping contributions from PBS-PFP and the dU host, and a weaker component around nm. As noted above for the more concentrated films, the excitation spectra differ from those of the monoliths and the low-concentration film.

These observations can be attributed to a combination of factors. First, the processing methodology used can lead to distinct kinetic control of the sol—gel process, in particular differences in the gelation times hours for the bulk and seconds for the films , which is known to modulate the degree of organization of the dU host material. In the film samples, the effect of aggregation becomes even more apparent, with the red shift in the emission band and change in the relative intensity of the vibronic peaks indicative of self-absorption usually designated as inner-filter effect.

Table 1. To further characterize the optical features of these materials, the refractive index n was monitored by spectroscopic ellipsometry. As mentioned above, one of the advantages of using the diureasil organic—inorganic hybrid as a host is the possibility to locally control the refractive index through UV exposure by direct writing with a UV pulsed laser.

The measured ellipsometric parameters I s and I c , and the respective fits are represented in Figures S2 and S3 Supporting Information. As an illustrative example, Figure 3 b presents the dispersion curves for UV-exposed regions of PBS2-M, revealing a refractive index increase with the UV dose used in the exposition. We note that the thin films, without UV exposure, behave as planar waveguides, where the propagation occurs without lateral confinement.

The emission spectra were acquired for a stripe length range of 0. Figure 5 a,b shows the respective ASE integrated intensity versus the stripe length for the planar and channel waveguides produced with PBS2-M. An increase in the ASE emission with the excitation length is clearly observed. The gain values obtained for the planar waveguide monoliths are represented in Figure 5 c, which show an increase of the optical gain values by increasing the polymer concentration in the diureasil.

The maximum optical gain obtained was Using the same approach, the optical gain coefficient was also calculated for the channel waveguides. The gain increase in the channel waveguide samples results from the confinement of the radiation, and therefore by the increase of the population inversion. Concluding, similarly to the refractive index, the optical gain can also be defined through chemical PBS-PFP doping and physical UV exposure parameters.

Signal propagation through the waveguide was attained, and an optical fiber was aligned to the channel output extremity to measure the output emission spectra, using a spectrometer. The spectra were taken, independently, without pump excitation, and with UV excitation through an external perpendicular pump source placed above the channel waveguide, and a UV pump co-propagating with the probe optical signal. From the spectra, an intensity improvement was observed when the waveguide was excited, especially for external perpendicular pumping.

To further evaluate the channel waveguides, the net optical gain dB was calculated. The output signal was detected by a photodiode connected to an oscilloscope. Again, an improvement in the intensity is observed when the waveguide is exposed to UV radiation, mainly when the excitation is external. The net gain values were estimated from the ratio between the peak-to-peak voltages of the received signal with and without pumping.

In this work, light propagation and amplification was attained with high optical gain efficiency values that envisage application of the proposed devices for VLC applications. In particular, to the best of our knowledge, larger or similar optical gain values were only achieved for pure polydioctylfluorene PFO 50 and poly 9,9-dioctylfluorene- co -9,9-di 4-methoxy phenylfluorene F8DP , 51 which has higher processing cost than our PBS-PFP-diureasil hybrid.

We note that compared to other hybrid materials, the gain efficiency values obtained are among the best previously reported in the literature Table 2. The highest gain efficiency values, calculated through the energy density, were 0. Table 2. As the gain efficiency values are comparable to those previously reported for both pure conjugated polymers and hybrid materials, PBS-PFP diureasils are a promising cost-effective solution for optical amplification in white light-emitting diodes for VLC.

Planar and channel waveguides based on PBS-PFP doped within diureasil organic—inorganic hybrids were fabricated and optically characterized with the view of their potential application as optical amplifiers for VLC based on white light-emitting diodes.

From the efficient and synergetic energy transfer between the diureasil-excited states and those of the PBS-PFP, an enhanced high-efficiency and stable emission in the blue spectral region peaking around — nm occurs, which overlaps that of commercial solid-state LEDs used for VLC.

We give emphasis to the heavily facilitated control of the surface optical properties by the inherent flexibility offered by these materials that are easily self-patterned by UV exposition laser writing, in contrast to traditional lithographic processes. This characteristic was exploited to pattern channel waveguides on the surface of PBS-PFP diureasil monoliths using direct UV laser writing, and radiation confinement was observed.

The optical gain coefficient was measured using the variable stripe length method, showing an increase in optical gain with the PBS-PFP concentration and with the irradiated UV energy amount. To further evaluate the channel waveguides, the net gain was measured, using an optical signal peaking at nm coupled in the input, transmitting bits, showing an intensity improvement when the waveguides were exposed to UV radiation.

The maximum gain efficiency value observed in planar waveguides was 0. In the channel waveguides, the highest gain efficiency obtained was 1. These values are among the best known for conjugated polymers and hybrid materials. To the best of our knowledge, larger values were only achieved for pure PFO, which has a higher processing cost than the hybrid material, showing the potential of the proposed material to be implemented as a cost-effective optical amplifier for VLC based on white light-emitting diodes.

Tetrahydrofuran THF The sol—gel reaction was triggered by the addition of ethanol 0. The samples were prepared as either freestanding monoliths or thin films.

To obtain the monoliths, the solution containing the gelation agents was transferred into a polypropylene mold, which was then covered with Parafilm M. Linear waveguides were patterned on the surface of the monoliths by direct laser writing, using an UV pulsed laser Coherent Bragg-Star Industrial V2.

UV—vis—NIR absorption spectra were recorded at room temperature, using a dual-beam Lambda spectrometer PerkinElmer with a mm diameter Spectralon integrating sphere or STD detector module over the scan range — nm and a resolution of 2 nm. The emission and excitation spectra were recorded at room temperature using a FluoroLog3 Horiba Scientific model FLT spectroscope, with a modular double-grating excitation spectrometer fitted with a grooves mm —1 grating blazed at nm and a TRIAX single emission monochromator fitted with a grooves mm —1 grating blazed at nm, reciprocal linear density of 2.

The excitation source was a W Xe arc lamp.

Advance in Microwave Photonics

Stimulated Brillouin scattering SBS is embedded today in a variety of optical systems, such as advanced high-power lasers, sensors, microwave signal processors, scientific instrumentation, and optomechanical systems. Reduction in SBS power requirements involves use of optical fibers, integrated optics, micro-optic devices, and now nano-optics, often in high Q cavities. It has taken fifty years from its earliest invention by conceptual discovery until today for SBS to become a practical and useful technology in a variety of applications. Some of these applications are explained and it is shown how they are tied to particular attributes of SBS: phase conjugation, frequency shifts, low noise, narrow linewidth, frequency combs, optical and microwave signal processing, etc. In we published a paper that first introduced the concept that the newly discovered stimulated Raman scattering SRS process creates coherent molecular oscillations.

Stimulated Brillouin Review: Invented 50 Years Ago and Applied Today

In this paper, the effects of homogeneous and inhomogeneous broadenings on the response of quantumdot semiconductor optical amplifier QD-SOAs are investigated. For the first time, the state space model is used to simulate static and dynamic characteristics of the QD-SOA. It is found that with decreasing the homogeneous and inhomogeneous broadenings, the saturation power of the QD-SOA decreases and the optical gain and the ultrafast gain compression increase. In addition, it is found that the homogeneous and inhomogeneous linewidths should be small for nonlinear applications. The homogeneous and inhomogeneous broadenings need to be large enough for linear applications. This is a preview of subscription content, access via your institution. Rent this article via DeepDyve. Spectral hole-burning and carrier-heating dynamics in InGaAs quantum-dot amplifiers. Article Google Scholar. Theory of optical signal amplification and processing by quantum-dot semiconductor optical amplifiers.

Erbium-Doped Fiber Amplifiers (EDFA)

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Electron-Ion Coupling Mechanism to Construct Stable Output Performance Nanogenerator

Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. The SAFADOF is able to significantly amplify very weak laser signals and reject noise in order to obtain clean signals in strong background. Having the ability to amplify weak signals with low background contribution, the SAFADOF finds outstanding potential applications in weak signal detections.

Homogeneous Broadening

This website uses cookies to deliver some of our products and services as well as for analytics and to provide you a more personalized experience. Click here to learn more. By continuing to use this site, you agree to our use of cookies. We've also updated our Privacy Notice. Click here to see what's new. Homogeneously broadened delay-line oscillators such as lasers or optoelectronic oscillators OEOs can potentially oscillate in a large number of cavity modes that are supported by their amplifier bandwidth. In a continuous wave operating mode, the oscillating mode is selected between one or few cavity modes that experience the highest small-signal gain. In this manuscript, we show that the oscillation mode of a homogeneously broadened oscillator can be selected from a large number of modes in a frequency region that can be broader than the full width at half maximum of the effective cavity filter.

Mechanical and Aerospace Engineering (MAE)

An important class of lumped optical amplifiers makes use of rare-earth elements as a gain medium by doping the fiber core during the manufacturing process. Although doped-fiber amplifiers were studied as early as , their use became practical only 25 years later, after their fabrication techniques were perfected. In such amplifiers, properties such as the operating wavelength and the gain bandwidth are determined by the dopants while silica plays the role of a host medium. Among the rare-earth elements, erbium is the most practical element to realize fiber amplifiers operating in the wavelength region near 1.

Ahead of Print / Just Accepted

RELATED VIDEO: Types of Optical Amplifier on basis of Application -- Booster , Pre and In-Line Amplifier.

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CHAPTER 3---- Laser Amplifiers 2015-7-2Fundamentals of Photonics 1 Chapter 3 Laser Amplifiers.

This chapter describes the determination of amplifying parameters in rare—earth—doped optical fiber laser amplifiers. In the context of this review, the system will be analyzed under both continuous—wave CW and pulse conditions. A comprehensive analysis has been implemented using the set of coupled propagation rate equations based on the atomic energy structure of dopant as well as the absorption and emission cross sections. Recently, intense activities have been devoted to characterize rare—earth—doped double—clad fiber laser amplifiers. Owing to their compactness, superb beam quality, great thermal control, and high efficiency, they demonstrate to be important light sources in medicine, modern telecommunication [ 1 ], and industries [ 2 , 3 ].

Gain Saturation in Optical Fiber Laser Amplifiers

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