With the application of freeform surface, beam shaping can achieve greater flexibility and precision. Ray mapping is an efficient geometric method for freeform surface design. However, the mapping may not always be integrable, which will result in actual performance falling short of expectations. Additionally, this method often relies on fitting the surface through the calculated coordinates of discrete points, and the fitting accuracy can also affect actual performance. In this study, adaptive weighted particle swarm optimization (AWPSO) is employed to optimize freeform polynomial coefficients to improve beam shaping performance. The initial freeform structure is obtained by non-integrable ray mapping method and fitted into a surface polynomial. Then, the process of optical design is transformed into a multi-dimensional optimization problem within mathematical models. Therefore, performance improvements do not depend on time-consuming ray tracing. A challenging beam shaping example of circle to regular hexagon is given to prove the effectiveness of the method. The results show a significant improvement in the uniformity of the ray spot on the target surface, with the contour becoming sharper and smoother after optimization. From the numerical results, the potential of this method is shown to be used in more irregular beam shaping conditions.
Flexible polymer optical waveguides demonstrate outstanding advantages over those on rigid substrates, including flexibility, bendability, lightweight, versatility, and ease of integration. However, flexible polymer optical waveguides face significant challenges in achieving efficient connection and integration with optical fibers. In this study, we propose a simple and reliable method for fabricating flexible polymer optical waveguides on polyimide (PI) using an ultraviolet (UV) lithography process. Additionally, MT connectors are fabricated at each end of the flexible waveguide with passive alignment features. This integration facilitates pluggable and efficient connections between waveguides and MT fiber arrays, significantly improving the ease of assembly and the reliability of optical connections. This integrated connector not only enhances the flexibility and reliability of applications in the field of optical interconnects but also lays the foundation for the development of future high-performance optoelectronic systems.
Polymer optical waveguide vertical optical coupler and mode division (de)multiplexer on optical printed circuit boards have garnered considerable attention. We have studied a stepped laser-ablation method for the fabrication of concave micromirrors in rectangular optical waveguides. The vertical coupling loss can be reduced to 1.83 dB experimentally. Further, based on gray-tone optical lithography technology combined with the overlay alignment method, a spherical concave micro-mirror has been fabricated, with the vertical coupling loss of 1.39 dB. Furthermore, a polymer three-mode (de)multiplexer with two cascaded waveguide directional couplers is proposed. The device can ensure that the E11 mode of the two narrower waveguides are highly coupled into the E21 and E31 modes of the central waveguide. The fabricated device exhibits coupling ratios of 98.07% and 95.43%. Moreover, a two-mode (de)multiplexer has been studied. The coupling ratio and extinction ratio of the fabricated (de)multi
The antiresonance spectral characteristics based on a silica capillary sandwiched between two single-mode fibers are investigated on the aspects of both transmission and reflection. Basic theory of the antiresonance reflecting optical waveguide model is presented and analyzed for this structure. During the fabrication, suitable parameters are adopted in in the manual welding process to keep the cross section of the capillary fiber away from the discharge electrode, which ensures the smoothness between the welding surfaces. Subsequently, three experimental samples are fabricated with the same inner diameter and various lengths of 650 μm, 837 μm, and 1070 μm, respectively. It can be observed that devices with different lengths have the same resonance wavelength in the wavelength range of 1500-1700 nm. However, the transmission depth at the resonance wavelength increases with the increase of the capillary length. We also discuss the relationship between inner diameter and transmission spectra through three samples with inner diameters of 25 μm, 50 μm, and 75 μm. The experimental results show that the free spectral range is 22.9 nm, 29.8 nm, and 44.1 nm, respectively. It also exists antiresonance in the reflection, which shows a novel mechanism for possible sensing applications.
It is demonstrated that the constitution of complex Faraday rotation in presence of intrinsic birefringence. We analyze the relationships between incident azimuth of linearly polarized light and birefringence and the influence of different orders birefringence on the measurement of magneto-optical effect. We proposed a relatively simple technique to accurately measure Faraday rotation of fiber. The order of birefringence in optical fiber and the high sensitivity magnetooptical characteristics can be determined by the measurement system.
This paper focuses on a method to decrease the scattering loss induced by surface roughness through waveguide structure optimization. First, the concept of roughness is discussed briefly, and the diagram of waveguide surface roughness tested by optical profiler is given. Then, this report mainly analyzes the influence on scattering loss coefficient and total loss coefficient induced by surface roughness under different waveguide parameters. The study finds that the scattering loss coefficient and the total loss coefficient increase as roughness increasing. Last, the part produces a method to decrease scattering loss induced by roughness through waveguide structure optimization importantly. It is found that the total scattering loss coefficient can be decreased greatly if waveguide core size is in range from 60 μm to 80 μm or the parameter Δ is smaller than 0.016. When surface roughness is 200 nm, the correlation length is 4 μm, waveguide length is 100 cm, and core width (height, a=b) is from 30 μm to 70 μm, the total scattering loss coefficient can decrease from 3.37×10-2 dB/cm to 1.65×10-2 dB/cm.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.