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Small-signal modulation characteristics of a polariton laser.

Baten MZ, Frost T, Iorsh I, Deshpande S, Kavokin A, Bhattacharya P - Sci Rep (2015)

Bottom Line: A maximum -3 dB modulation bandwidth of 1.18 GHz is measured.The experimental results have been analyzed with a theoretical model based on the Boltzmann kinetic equations and the agreement is very good.Gain compression phenomenon in a polariton laser is interpreted and a value is obtained for the gain compression factor.

View Article: PubMed Central - PubMed

Affiliation: Center for Photonics and Multiscale Nanomaterials, Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Avenue, Ann Arbor, MI 48109, USA.

ABSTRACT
Use of large bandgap materials together with electrical injection makes the polariton laser an attractive low-power coherent light source for medical and biomedical applications or short distance plastic fiber communication at short wavelengths (violet and ultra-violet), where a conventional laser is difficult to realize. The dynamic properties of a polariton laser have not been investigated experimentally. We have measured, for the first time, the small signal modulation characteristics of a GaN-based electrically pumped polariton laser operating at room temperature. A maximum -3 dB modulation bandwidth of 1.18 GHz is measured. The experimental results have been analyzed with a theoretical model based on the Boltzmann kinetic equations and the agreement is very good. We have also investigated frequency chirping during such modulation. Gain compression phenomenon in a polariton laser is interpreted and a value is obtained for the gain compression factor.

No MeSH data available.


Related in: MedlinePlus

Dynamic characteristics of polariton laser.a, Frequency response derived from measured time resolved electroluminescence at different DC injection levels. The solid lines represent the corresponding frequency responses calculated from the modulation transfer function (see Methods). Inset shows the measured transient response of the polariton laser to a high speed switching pulse at J = 5.4Jth. b, Measured resonance frequency as function of  , where  is the steady-state ground state occupancy at . The solid line shows the calculated values from equation (2) for the given scattering rate, b and polariton lifetime, τLP. c, Variation of the damping factor as a function of the square of the resonance frequency. d, measured linewidth of LP emission peak as a function of the small signal modulating frequency, under a fixed DC bias of 1.15 Jth.
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f3: Dynamic characteristics of polariton laser.a, Frequency response derived from measured time resolved electroluminescence at different DC injection levels. The solid lines represent the corresponding frequency responses calculated from the modulation transfer function (see Methods). Inset shows the measured transient response of the polariton laser to a high speed switching pulse at J = 5.4Jth. b, Measured resonance frequency as function of , where is the steady-state ground state occupancy at . The solid line shows the calculated values from equation (2) for the given scattering rate, b and polariton lifetime, τLP. c, Variation of the damping factor as a function of the square of the resonance frequency. d, measured linewidth of LP emission peak as a function of the small signal modulating frequency, under a fixed DC bias of 1.15 Jth.

Mentions: To investigate and analyze the dynamic characteristics of the polariton laser, we have measured the small signal modulation response of the device. The modulation response at various injection levels is shown in Fig. 3(a). A −3 dB modulation bandwidth of 1.18 GHz was measured at an injection current density of 5.4 Jth and the resonance frequency, fr, at this injection level is 0.9 GHz. The solid curves in Fig. 3(a) represent the modulation response calculated in accordance with the transfer function described in the Methods section. Emission is stimulated in a conventional photon laser, whereas in the polariton laser polariton-polariton scattering is stimulated once the occupation is unity. The separation of stimulation and emission in a polariton laser leads to coherent emission without the requirement for population inversion. Iorsh et al.27 have theoretically investigated the small-signal modulation behavior of III-nitride electrically pumped polariton lasers. According to their theory, the resonance frequency of the modulation response, ωR(pol), in the framework of the Boltzmann kinetic model (see Methods for details), is given by:


Small-signal modulation characteristics of a polariton laser.

Baten MZ, Frost T, Iorsh I, Deshpande S, Kavokin A, Bhattacharya P - Sci Rep (2015)

Dynamic characteristics of polariton laser.a, Frequency response derived from measured time resolved electroluminescence at different DC injection levels. The solid lines represent the corresponding frequency responses calculated from the modulation transfer function (see Methods). Inset shows the measured transient response of the polariton laser to a high speed switching pulse at J = 5.4Jth. b, Measured resonance frequency as function of  , where  is the steady-state ground state occupancy at . The solid line shows the calculated values from equation (2) for the given scattering rate, b and polariton lifetime, τLP. c, Variation of the damping factor as a function of the square of the resonance frequency. d, measured linewidth of LP emission peak as a function of the small signal modulating frequency, under a fixed DC bias of 1.15 Jth.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4495564&req=5

f3: Dynamic characteristics of polariton laser.a, Frequency response derived from measured time resolved electroluminescence at different DC injection levels. The solid lines represent the corresponding frequency responses calculated from the modulation transfer function (see Methods). Inset shows the measured transient response of the polariton laser to a high speed switching pulse at J = 5.4Jth. b, Measured resonance frequency as function of , where is the steady-state ground state occupancy at . The solid line shows the calculated values from equation (2) for the given scattering rate, b and polariton lifetime, τLP. c, Variation of the damping factor as a function of the square of the resonance frequency. d, measured linewidth of LP emission peak as a function of the small signal modulating frequency, under a fixed DC bias of 1.15 Jth.
Mentions: To investigate and analyze the dynamic characteristics of the polariton laser, we have measured the small signal modulation response of the device. The modulation response at various injection levels is shown in Fig. 3(a). A −3 dB modulation bandwidth of 1.18 GHz was measured at an injection current density of 5.4 Jth and the resonance frequency, fr, at this injection level is 0.9 GHz. The solid curves in Fig. 3(a) represent the modulation response calculated in accordance with the transfer function described in the Methods section. Emission is stimulated in a conventional photon laser, whereas in the polariton laser polariton-polariton scattering is stimulated once the occupation is unity. The separation of stimulation and emission in a polariton laser leads to coherent emission without the requirement for population inversion. Iorsh et al.27 have theoretically investigated the small-signal modulation behavior of III-nitride electrically pumped polariton lasers. According to their theory, the resonance frequency of the modulation response, ωR(pol), in the framework of the Boltzmann kinetic model (see Methods for details), is given by:

Bottom Line: A maximum -3 dB modulation bandwidth of 1.18 GHz is measured.The experimental results have been analyzed with a theoretical model based on the Boltzmann kinetic equations and the agreement is very good.Gain compression phenomenon in a polariton laser is interpreted and a value is obtained for the gain compression factor.

View Article: PubMed Central - PubMed

Affiliation: Center for Photonics and Multiscale Nanomaterials, Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Avenue, Ann Arbor, MI 48109, USA.

ABSTRACT
Use of large bandgap materials together with electrical injection makes the polariton laser an attractive low-power coherent light source for medical and biomedical applications or short distance plastic fiber communication at short wavelengths (violet and ultra-violet), where a conventional laser is difficult to realize. The dynamic properties of a polariton laser have not been investigated experimentally. We have measured, for the first time, the small signal modulation characteristics of a GaN-based electrically pumped polariton laser operating at room temperature. A maximum -3 dB modulation bandwidth of 1.18 GHz is measured. The experimental results have been analyzed with a theoretical model based on the Boltzmann kinetic equations and the agreement is very good. We have also investigated frequency chirping during such modulation. Gain compression phenomenon in a polariton laser is interpreted and a value is obtained for the gain compression factor.

No MeSH data available.


Related in: MedlinePlus