• Current Optics and Photonics
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• v.6 no.1
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• pp.23-31
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• 2022

Heterodyne efficiency is an indicator to evaluate the performance of space coherent laser communication systems. It is affected by signal light and local oscillator (LO) light amplitude, phase and polarization state. In this paper, based on the common heterodyne efficiency, a heterodyne efficiency model that can reflect polarization aberration of optical system is proposed. The heterodyne efficiency is analyzed when the signal light and the LO light are linearly polarized or circularly polarized. For a coherent communication optical system, when the incident signal light is right-circularly polarized light and the incident LO light is 45° linear polarized light. Based on the three-dimensional ray tracing theory and the heterodyne efficiency proposed in this paper, the change of polarization states and the distribution of heterodyne efficiency of the signal light and LO light influenced by the optical system's polarization aberration are analyzed. Analysis shows that the heterodyne efficiency model proposed in this paper can be used to evaluate coherent communication systems and reflect the influence of optical system polarization aberration.

• Current Optics and Photonics
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• v.1 no.4
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• pp.295-307
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• 2017

An innovative system for the alternative continuous wide spectral spatial heterodyne spectrometer (ACWS-SHS) is proposed. The relationship between the ACWS-SHS and the wide spectral spatial heterodyne spectrometer (WS-SHS) at the resolution limit, the spectral range, the grating diffraction efficiency and the interference fringes contrast ratio has been analyzed theoretically. Through the comparison of the theoretical analysis and simulation results, it is found that the two systems for the WS-SHS and the ACWS-SHS have the same resolution limit and spectral range, which are ${\delta}{\sigma}$ and ${\sigma}_{01}$, while in the ACWS-SHS system the critical diffraction efficiency of echelle grating is 68.39% and the critical contrast ratio of interference fringes is 0.4135, which is much better than the performance of the WS-SHS system. Therefore, the ACWS-SHS reduces the high requirements for the precision of equipment and expands the application field of SHS effectively.

• Journal of Sensor Science and Technology
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• v.7 no.5
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• pp.306-312
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• 1998

To develop the multi-channel fiber-optic sensor array system, two-channel TDM(Time Division Multiplexing) fiber-optic sensor array was constructed and characterized. The sensor array topology was Mach-Zehender ladder type and PMDI(Phase-Matched Differential Interferometer) technique was used to exploit the efficiency of the array signal processing. By using a synthetic heterodyne demodulation technique, outputs of the two channels were monitored simultaneously. The sensitivities of channel #1 and #2 were measured ${\sim}60{\mu}rad/\sqrt{Hz}$ and ${\sim}80{\mu}rad/\sqrt{Hz}$, respectively. Crosstalk of sensors in the array was found to be approximately -36dB. Based on the results, we could conclude that TDM Mach-Zehnder ladder type sensor array can be used to detect the acoustic signal with stability and efficiency of the sensor array.

• Journal of the Optical Society of Korea
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• v.5 no.3
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• pp.99-109
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• 2001

This paper presents a phase-only modulation scheme for a three-dimensional (3-D) image matching system to improve optical efficiency of the system. The 3-D image matching system is based on the two mask heterodyne scanning. A hologram of the 3-D reference object is first created and then the phase of the hologram is extracted. The phase of the hologram is represented as one mask with the other mask being a plane wave. The superposition of each beam modulated by the two masks generated a scanning beam pattern. This beam pattern scans the 3-D target object to be recognized. The output of the scanning system gives out the correlation of the phase-only hologram of the reference object and the complex hologram of the target object. Since a hologram contains 3-D information of an object as a form of fringe pattern, the correlation of holograms matches whole 3-D aspect of the objects. Computer simulations are performed with additive gaussian noise and without noise for the complex hologram modulation scheme and the phase-only hologram modulation scheme. The computer simulation results show that the phase-only hologram modulation scheme improves the optical efficiency. Thus the system with the phase-only hologram modulation scheme is more robust than the system with the complex hologram modulation scheme.