研究目的
To analyze the coherence properties of an octave-spanning mid-infrared supercontinuum source generated in an air clad SiGe/Si waveguide and its implications for absorption spectroscopy, on-chip optical frequency metrology, and ??-to-2?? interferometry applications.
研究成果
The study demonstrates that engineering two closely spaced zero-dispersion wavelengths enclosing an anomalous dispersion band can produce supercontinuum pulses with high spectral density and full coherence at the extreme ends of the spectrum. This approach is beneficial for applications requiring high coherence, such as absorption spectroscopy and optical frequency metrology, without the need for sub-100 fs pump pulses or high multi-photon absorption.
研究不足
The study is limited by the assumptions made in the numerical model, such as constant propagation loss and the neglect of recombination lifetime in the free-carrier density model. Additionally, the experimental setup may be affected by water vapor absorption and increased propagation loss at certain wavelengths not considered in simulations.
1：Experimental Design and Method Selection:
The study involves a numerical analysis of the coherence properties of a mid-infrared supercontinuum generated in a SiGe/Si waveguide. The methodology includes the use of the generalized nonlinear Schrodinger equation (GNLSE) under the slowly varying envelope approximation to model pulse propagation.
2：Sample Selection and Data Sources:
The device under study is a 7 cm long Si
3：6Ge4 on Si (001) air-clad waveguide with a 75 μm × 70 μm cross-section. List of Experimental Equipment and Materials:
The waveguide is pumped by a tunable OPA laser (MIROPA-fs, Hotlight Systems) delivering 205 fs pulses centered at 4 μm.
4：Experimental Procedures and Operational Workflow:
The propagation of short optical pulses in the waveguide is described by the GNLSE, considering high-order dispersions up to ??10, nonlinear Raman response, and free-carrier effects.
5：Data Analysis Methods:
The degree of first-order coherence of the supercontinuum is calculated from an ensemble average over independently generated pairs of supercontinua with random input noise.
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