This theoretical modeling and simulation paper
presents designs and projected performance of an on-chip digital
Fourier transform spectrometer using a thermo-optical (TO)
Michelson grating interferometer operating at∼1550 and 2000 nm
for silicon-on-insulator and for germanium-on-silicon technological
platforms, respectively. The Michelson interferometer arms
consist of two unbalanced tunable optical delay lines operating in
the reflection mode. They are comprised of a cascade connection
of waveguide Bragg grating resonators (WBGRs) separated by a
piece of straight waveguide with lengths designed according to the
spectrometer resolution requirements. The length of eachWBGRis
chosen according to the Butterworth filter technique to provide one
resonant spectral profile with a bandwidth twice that of the spectrometer
bandwidth. A selectable optical path difference (OPD)
between the arms is obtained by shifting the notch in the reflectivity
spectrum along the wavelength axis by means of a low-power TO
heater stripe atop the WBGR, inducing an OPD that depends on
the line position of the WBGR affected by TO switching.We examined
the device performances in terms of signal recostruction in the
radio-frequency (RF) spectrum analysis application at 1 GHz and
at 1.5 GHz of spectrometer resolution. The investigation demonstrated
that high-quality spectrum reconstruction is obtained for
both Lorentzian and arbitrary input signals with a bandwidth
up to 40 GHz. We also show that spectrum reconstruction of
100–200 GHz RF band input signals is feasible in the Ge-on-Si
chips.
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Novel Measurement-Based Efficient Computational Approach to Modeling Optical Power Transmission in Step-Index Polymer Optical Fiber
Polymer optical fibers (POFs) are playing an important role in industrial applications nowadays due to their ease of handling and resilience to bending and environmental effects. A POF can tolerate a bending radius of less than 20 mm, it can work in environments with temperatures ranging from −55 °C to +105 °C, and its lifetime is around 20 years. In this paper, we propose a novel, rigorous, and efficient computational model to estimate the most important parameters that determine the characteristics of light propagation through a step-index polymer optical fiber (SI-POF). The model uses attenuation, diffusion, and mode group delay as functions of the propagation angle to characterize the optical power transmission in the SI-POF. Taking into consideration the mode group delay allows us to generalize the computational model to be applicable to POFs with different index profiles. In particular, we use experimental measurements of spatial distributions and frequency responses to derive accurate parameters for our SI-POF simulation model. The experimental data were measured at different fiber lengths according to the cut-back method. This method consists of taking several measurements such as frequency responses, angular intensity distributions, and optical power measurements over a long length of fiber (>100 m), then cutting back the fiber while maintaining the same launching conditions and repeating the measurements on the shorter lengths of fiber. The model derivation uses an objective function to minimize the differences between the experimental measurements and the simulated results. The use of the matrix exponential method (MEM) to implement the SI-POF model results in a computationally efficient model that is suitable for POF-based system-level studies. The efficiency gain is due to the independence of the calculation time with respect to the fiber length, in contrast to the classic analytical solutions of the time-dependent power flow equation. The robustness of the proposed model is validated by calculating the goodness-of-fit of the model predictions relative to experimental data.
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- Award ID(s):
- 1809242
- NSF-PAR ID:
- 10354317
- Date Published:
- Journal Name:
- Photonics
- Volume:
- 9
- Issue:
- 4
- ISSN:
- 2304-6732
- Page Range / eLocation ID:
- 260
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/photonics9040260
