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High resonance frequency in a coupled cavity DFB-LD with two phase-shifts
摘要： To realize a single-longitudinal-mode laser diode (LD) with high speed direct-modulation, a coupled cavity DFB-LD with two phase-shifts is proposed. From simulated results, it is expected that the resonance frequency of 71.3 GHz and the 3-dB down bandwidth of 95.9 GHz are obtained when the injected current is 3.075 times the threshold current. The resonance frequency for a main-mode is enhanced by an interaction between the main-mode and sub-mode. This interaction is called photon–photon resonance. The proposed coupled cavity DFB-LD is composed of two regions which are connected in series. Both regions have phase-shifted gratings. The phase-shift of the first region is ? π; the phase-shift of the second region is ? 0.9π. A phase-shift is not introduced at the interface of the two regions. The corrugation pitch of the second region is shorter than that of the first region by 1.6 nm; the grating coupling coefficient is 40 cm?1; each region length is 300 μm. These parameters are modest to fabricate DFB-LDs.
关键词： Longitudinal mode,Coupled cavity,Direct modulation,Semiconductor laser,Diffraction grating
更新于2025-09-23 15:19:57
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Sn-doped CdS Nanowires with Low Temperature Lasing by CW-Laser Excitation
摘要： Sn-doped CdS nanowires, with the inside coexisting Sn(II)S, Sn2(III)S3 and Sn(IV)S2 identified by in situ Raman and XPS spectra, are grown via a simple thermal evaporation deposition technique. Its room-temperature photoluminescence (PL) spectrum shows a broad ingap emission band out of different Sn dopants which is also superposed by a series of weak modes from a microcavity due to the wire size and its structure, besides the CdS bandedge emission and a sideband emission due to SnS2. The ratio of the intensity of the ingap emission versus that of the bandedge emission is only 1/4 at room temperature, but it can be remarkably increased to about 7 at 80K. This significant enhancement of the ingap emission may be attributed to the local plasma coming from more bound carriers and enhanced microcavity effect at low temperature by analyzing the temperature-dependent PL and Raman spectra in detail. For these reasons, the bandedge and ingap emission both can realize lasing excitated by a continuous laser at 80K. The results would provide a way to get temperature tunable low threshold microscale lasers and study the plasma-polariton process within microcavity.
关键词： Sn-doped nanowires,plasma,cavity modes,lasing,coupled cavity
更新于2025-09-12 10:27:22
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Slow-Light Frequency Combs and Dissipative Kerr Solitons in Coupled-Cavity Waveguides
摘要： We study Kerr frequency combs and dissipative Kerr solitons in silicon photonic crystal coupled-cavity waveguides (CCWs) with globally optimized dispersion at telecom wavelengths. The corresponding threshold for comb generation is found to explicitly depend on the main CCW figures of merit, namely, the mode volume, the normal-mode quality factor, and the slow-light group index. Our analysis is carried out by solving the nonlinear dynamics of the CCW Bloch modes in the presence of Kerr nonlinearity and two-photon absorption. Our results open the way to CCW comb generation via dispersion engineering and slow-light enhancement.
关键词： dissipative Kerr solitons,silicon photonic crystal,dispersion engineering,slow-light enhancement,coupled-cavity waveguides,Kerr frequency combs
更新于2025-09-12 10:27:22
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Investigation of a passively Q-switched Raman laser at 1176?nm with Nd3+:YAG/Cr4+:YAG/YAG composite crystal and a coupled cavity
摘要： To reduce the thermal lens effect and increase the efficiency, a composite crystal of Nd3+:YAG/Cr4+:YAG/YAG and a coupled cavity structure were employed in our passively Q-switched YVO4-based Raman laser system. Both the simulation and the experiment results showed that the undoped YAG crystal bonded in the end-face of Cr4+:YAG crystal can speed up the heat transfer of Cr4+:YAG crystal and reduce the temperature difference between its side surfaces and the center significantly, and the coupled cavity structure can improve the laser performance, especially at high pump power. The maximum output power of Raman laser of 0.92 W at 1176 nm was obtained with an optical-to-optical efficiency of 11.51%. The corresponding repetition rate and the pulse width is 53.5 kHz and 3.22 ns, respectively.
关键词： Composite crystal,Passively Q-switched,Temperature field,Coupled cavity,Raman,Finite element method
更新于2025-09-12 10:27:22
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AIP Conference Proceedings [AIP Publishing LLC OPTOELECTRONIC MATERIALS AND THIN FILMS: OMTAT 2013 - Kochi, Kerala, India (3–5 January 2013)] - Dynamics of atom-field probability amplitudes in a coupled cavity system with Kerr non-linearity
摘要： We have investigated the dynamics of two cavities coupled together via photon hopping, filled with Kerr non-linear medium and each containing a two level atom in it. The evolution of various atom (field) state probabilities of the coupled cavity system in two excitation sub space are obtained numerically. Detailed analysis has been done by taking different initial conditions of the system, with various coupling strengths and by varying the susceptibility of the medium. The role of susceptibility factor, on the dynamics atom field probability has been examined. In a coupled cavity system with strong photon hopping it is found that the susceptibility factor modifies the behaviour of probability amplitudes.
关键词： Two level atom,Kerr medium,Coupled cavity
更新于2025-09-12 10:27:22
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Double-wavelength nanolaser based on strong coupling of localized and propagating surface plasmon
摘要： We theoretically demonstrate a kind of plasmon coupled cavity to achieve a nanolaser with high intensity and low threshold. The plasmon cavity is composed of the gold film substrate and gold disk array, which supports two strong coupled resonance modes (i.e. surface plasmon polariton (SPP) and localized surface plasmon (LSP)). Compared with the nanolaser with the LSP resonance structure, the scattering cross-section of the LSP-SPP coupled laser is 80 times higher. The coupled cavity nanolaser with different wavelengths can be excited with different plasmon resonance modes by selecting the appropriate gain medium. In addition, a compact tunable dual-wavelength laser can be developed using this coupled structure.
关键词： localized surface plasmon,nanolaser,surface plasmon polariton,dual-wavelength laser,plasmon coupled cavity
更新于2025-09-12 10:27:22
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Counterpropagating continuous-variable entangled states in lossy coupled-cavity optical waveguides
摘要： We present an integrated source of counterpropagating entangled states based on a coupled resonator optical waveguide that is pumped by a classical pulsed source incident from above the waveguide. We investigate theoretically the generation and propagation of continuous-variable entangled states in this coupled-cavity system in the presence of intrinsic loss. Using a tight-binding approximation, we derive analytic time-dependent expressions for the number of photons in each cavity, as well as for the correlation variance between the photons in different pairs of cavities, to evaluate the degree of quantum entanglement. We also derive simple approximate expressions for these quantities that can be used to guide the design of such systems, and discuss how pumping configurations and physical properties of the system affect the photon statistics and the degree of quantum correlation.
关键词： quantum entanglement,lossy coupled-cavity optical waveguides,continuous-variable entangled states,counterpropagating,tight-binding approximation
更新于2025-09-11 14:15:04