Group-IV Ge1-xSnx alloys have attracted much attention due to their optical properties and variable band structures. In this work, a strain-adjustable Si0.1Ge0.78Sn0.12/Ge0.90Sn0.10/Si0.012Ge0.848Sn0.14 double-heterostructure short-wave infrared photodetector with giant magnetostrictive stressor is designed and characterized theoretically. Adjustable uniaxial tensile strain from 0 to 0.11% is introduced into Ge0.90Sn0.10 photodetector by adjusting the external magnetic field range from 0eV to 240kA/m to realize a continuously adjustable bandgap of 0.534eV ~ 0.461eV, thus obtaining the detection wavelength between 2.32μm and 2.69μm in short-wave infrared, which provide new ideas for the integration of magnetic-force-electricaloptical devices and next-generation optical communication systems in SWIR.
Self-mixing interferometry (SMI) is a well-developed sensing technology. An SMI system can be described using a model derived from the well-known Lang and Kobayashi equations by setting the system operating in stable region. The features of an SMI signal are determined by the external optical feedback factor (denoted by C). Our recent work shows that when the factor C increases to a certain value, e.g. in moderate feedback regime with 1<C<4.6, the SMI system might enter unstable region and the existing SMI model is invalid. In this case, the SMI signals exhibit some novel features and contain higher-frequency components. To detect an SMI signal without distortion or take suitable correction on the SMI signal, it is must to make an analysis on the system bandwidth and its influence on SMI signals. The results in this paper provide useful guidance for developing an SMI sensing system.
Material parameters such as Young’s modulus and internal friction are important for estimation of material performance. This paper presents an experimental study for measuring material related parameters using a selfmixing interferometric (SMI) configuration. An SMI system consists of a laser diode (LD), a lens and an external target to be measured. When a part of the lasing light back-reflected or back-scattered by the external target re-enters the LD internal cavity, both optical frequency and intensity of the lasing light can be modulated. This modulated laser intensity is often referred as SMI signal. Generally, the target related movement or its surface information can be retrieved from this SMI signal. In this paper, an SMI system is implemented. A tested sample is used as the target to form the external cavity of the LD. The tested sample is stimulated in vibration. Continuous wavelet transform (CWT) is utilized to retrieve the vibration information of the tested sample from an SMI signal. We are able to obtain both Young’s modulus and internal friction from a piece of an experimental SMI signal. This work provides a novel, simple non-destructive solution for simultaneous measurement of Young’s modulus and internal friction.
When a fraction of external optical feedback re-enters inside cavity of a laser diode (LD), the laser intensity and its wavelength will thus be altered. The LD in this case is often called as a self-mixing laser diode (SMLD). This paper presents an SMLD for profile measurement. The LD is modulated by the injection current in triangular waveform and a target to be measured is installed on a mechanic scanning device. The reflection light by the target contains its surface profile. The profile information is then carried in the laser intensity and can be pickup by a photodiode packaged in the rear of the LD. We call this modulated laser intensity as self-mixing interferometric (SMI) signal. In this paper, a new algorithm is developed to retrieve the profile from the SMI signal. Results show that the proposed design is able to achieve the measurement of profile with high resolution.
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