Pseudo-self-imaging phenomenon in multimode waveguide and its application

Abstract

The self-image profiles in a multimode waveguide can be estimated from the phase relations of the guided-modes. However, in MMI theory, the propagation constants of each guided-mode are defined as a perfectly confined condition. Because of the effect of the Goos-Hänchen shift, there are large phase differences for each guided-mode between the predictions of MMI theory and the actual phenomena. Because the relative phases of the guided-modes are not the same as the theoretical ones in a multimode waveguide, it is possible that an undefined self-image can be produced. In this paper, such a phenomenon is called the 'pseudo-self-imaging phenomenon'. This phenomenon can be observed in both the simulation and the experimental results. The excess loss has been measured, and the results are the same as -0.5dB for both the 1st 0-dB self-image and the 1st pseudo-self-image. These results may have been occurred by the phase mismatch of the guided-modes. The extinction ratios are also measured, and the results are 15.5dB for the 0-dB selfimage and 16.2dB for the pseudo-self-image. From the result, it is shown that the pseudo-self-image is formed after the 0-dB self-image and the pseudo-self-images' intensity can be higher then the 0-dB self-images.

Building large area CZT imaging detectors for a wide-field hard X-ray telescope—ProtoEXIST1

“…For instance, in order to reduce the capacitance noise on the ASIC input, we introduced narrow traces (3 mil) and the low dielectric constant material (Arlon NT55 or ST55) for the latest revision of these boards. The capacitance-induced noise estimates and the measured electronics noise of the bare DCUs (IPB+ASIC, no crystal) match very well [4,5], demonstrating one of the dominant components of electronics noise we observe is the large capacitance of the long traces in the IPB's between the anode pixels and the ASIC inputs (see also Fig. 11 in §5).…”

“…It is also capable of multipixel pulse-profile readout, which can provide the depth (z) information of the interaction as well as x, y and the energy deposit (E). The flexible readout mode also allows for the complete reconstruction of multi-pixel trigger events arising from charge splitting or Compton scattering [5,9]. The reconstruction of Compton scattered events makes possible the polarization measurement of detected X-rays and the full recovery of the total energy deposited through multiple interactions within the detector.…”

“…1). An extensive description of the early development of the telescope and detector plane can be found in [4,5,6] …”

“…2, when the post-trigger samples are lower in amplitude than the pre-trigger samples, negatively induced charges are then recorded. Negative charges are usually induced in pixels neighboring triggered pixels due to slow-moving holes, and the total sum of the induced signal in neighbor pixels is proportional to the depth of the interaction [8,5,9].…”

“…EXIST is the leading candidate for the Black Hole Finder Probe under NASA's Beyond Einstein Program 4 , which is currently undergoing further development as part of the Advanced Mission Concept Study Program 5 . The main goals of EXIST are to perform an unbiased survey of black holes on all scales and to probe the early universe through the detection of high redshift (z 7) GRB's.…”