Complex Kernel-based spectrum reconstruction algorithm for cascaded Fabry-Perot interferometric spectrometer.

A method to calculate the spectrum of the light incident on a cascaded Fabry-Perot interferometric spectrometer from the detector signal versus the scanning mirror position is presented. The method is based on modifying the Fabry-Perot integral equation to reduce possible spectrum reconstruction errors that arise due to inaccurate determination of the optical path difference reference position and the dependence on the dispersion of the cavity material. A transformation algorithm that employs the suggested kernel modification is derived and tested.

On-chip parallel Fourier transform spectrometer for broadband selective infrared spectral sensing.

Optical spectrometers enable contactless chemical analysis. However, decreasing both their size and cost appears to be a prerequisite to their widespread deployment. Chip-scale implementation of optical spectrometers still requires tackling two main challenges.

Autoregressive superresolution microelectromechanical systems Fourier transform spectrometer.

In this work, the application of the superresolution autoregressive (AR) model to enhance the resolution of the microelectromechanical systems (MEMS) Fourier transform infrared spectrometer (FTIR) spectrometer is studied theoretically and experimentally. The effect of the number of spectral lines, the spacing between the lines, the resolution of the MEMS FTIR spectrometer and the signal-to-noise ratio (SNR) on the prediction accuracy is addressed for different targeted prediction resolutions. The effect of the SNR on applying the AR model is studied.

Transformation algorithm and analysis of the Fourier transform spectrometer based on cascaded Fabry-Perot interferometers.

The Fourier transform spectrometer based on cascaded Fabry-Perot interferometers is analyzed, where one of the interferometers has a fixed length, while the other is scanning. We propose a method to reconstruct the spectrum correctly based on solving the integral equation of the overall response of the cascaded interferometers. The method is tested for different design parameters and noise conditions.

Transmission-enabled fiber Fabry-Perot cavity based on a deeply etched slotted micromirror.

In this work, we report the analysis, fabrication, and characterization of an optical cavity built using a Bragg-coated fiber (BCF) mirror and a metal-coated microelectromechanical systems (MEMS) slotted micromirror, where the latter allows transmission output from the cavity. Theoretical modeling, using Fourier optics analysis for the cavity response based on tracing the propagation of light back and forth between the mirrors, is presented. Detailed simulation analysis is carried out for the spectral response of the cavity under different design conditions.

Fourier transform spectrometer based on Fabry-Perot interferometer.

We analyze the Fourier transform spectrometer based on a symmetric/asymmetric Fabry-Perot interferometer. In this spectrometer, the interferogram is obtained by recording the intensity as a function of the interferometer length. Then, we recover the spectrum by applying the discrete Fourier transform (DFT) directly on the interferogram.

Dispersion compensation in Fourier domain optical coherence tomography.

In this work, we propose a numerical technique to compensate for errors due to dispersion effects in Fourier domain optical coherence tomography. The proposed technique corrects for errors in depth measurements and resolution loss due to dispersion. The results show that, by using this technique, errors in thickness measurement are reduced from about 5% to less than 0.

Performance evaluation of a metal-insulator-metal surface plasmon resonance optical gas sensor under the effect of Gaussian beams.

In this work, the performance of a nonconventional IR surface plasmon resonance (SPR) gas sensor structure based on the use of a metal-insulator-metal (MIM) structure is studied. This MIM-based sensor structure gives enhanced performance five times better than the conventional MI SPR optical gas sensors. The performance of the SPR gas sensors is studied under the effect of oblique incident Gaussian beams with different spot sizes, and the performance enhancement of the MIM structure is confirmed for different spot sizes.

Signal-to-noise ratio calculation in a moving-optical-wedge spectrometer.

In this paper we study the signal-to-noise ratio degradation in a moving-optical-wedge interferometer when used as an optical spectrometer. Both the mechanical vibration and temperature fluctuation effects are studied, and the effects are compared to their counterparts in a conventional Michelson interferometer. While the wedge interferometer is found to be more immune to linear translational vibration, it shows much higher sensitivity to rotational vibration.

Spot size effects in miniaturized moving-optical-wedge interferometer.

In this paper we study the effect of diffraction on the performance of a miniaturized moving-optical-wedge interferometer. By using the Gaussian model, we calculate the degradation of the interferometer visibility due to diffraction effects. We use this model to optimize the detector size required to obtain maximum visibility and study its effect on resolution of Fourier transform spectrometers based on a moving-optical-wedge interferometer.

Diffraction effects in optical microelectromechanical system Michelson interferometers.

We study the effect of diffraction on the performance of microelectromechanical system Michelson interferometers. By using a simple Gaussian model, we calculate the degradation of the interferometer visibility due to the diffraction effect. We then use this model to estimate the optimum detector diameter to maximize the fringe visibility at the interferometer output and study its effect on the resolution of Fourier transform spectrometers based on Michelson interferometers.

Steady and oscillating multiple dissipative solitons in normal-dispersion mode-locked Yb-doped fiber laser.

Multiple dissipative solitons are numerically studied in the normal-cavity-dispersion Yb-doped fiber laser. Soliton pairs and triplets of different types are found in parameter domain where single soliton mode-locking is unstable. Similar scenario is found for soliton pair and triplet: an additional weak soliton supplements already existing solitons, then with increasing gain the solitons start oscillating and at higher gain the soliton complex becomes stable.

Dispersion compensation in moving-optical-wedge Fourier transform spectrometer.

In this paper we study the effect of material dispersion on the performance of a moving-optical-wedge Fourier transform spectrometer. The spectrum is thus evaluated numerically using a test spectrum source. The obtained numerical results show that the classical technique for numerical dispersion compensation, usually used with a Michelson interferometer, cannot be efficiently used with wedge interferometers as it is limited to the cases of weak dispersion.

Properties and stability limits of an optimized mode-locked Yb-doped femtosecond fiber laser.

Stable mode-locked operation in a simple normal-cavity-dispersion laser oscillator that consists of only Yb-doped fiber and saturable absorber is studied. The Yb-doped fiber design parameters: group velocity dispersion (GVD), nonlinearity coefficient, bandwidth (Yb-BW), length and gain are considered to be the controlling parameters of the laser cavity. The pulse characteristics such as the temporal width, spectrum and pulse energy as a function of these elements are reported here.

Straight multimode interference phased array structure using periodic segmented waveguide phase array.

A new design of a multimode interference (MMI) phased array structure is proposed. This design is based on replacing the arrayed delay arms between the first MMI power splitter and the second MMI combiner by periodic segmented waveguides. This allows a straight structure without curved waveguides and thus reduces greatly the size of the structure.