If we want to calculate the temperature dependence of the effective index, we can change the silicon material to be "Si with T dependence" and the glass to be "SiO2 with T dependence". In this example, we will design an integrated biosensor circuit and calculate its sensitivity to small refractive index changes due to the presence of an analyte on a waveguide. To see all 3 guided modes, the symmetric boundaries can be removed.
The FSR of an ideal Mach-Zehnder is given by, $$ F S R=\frac{c}{n_{g}\left(L_{2}-L_{1}\right)} $$. We can export the change in effective index to a text file, called delta_neff_vs_index.txt, that can be used by INTERCONNECT with the following lines of script. Refractive index database [about] Shelf ... Optical functions of silicon-germanium alloys determined using spectroscopic ellipsometry, Opt. REFERENCES: (1) Handbook Optical Constants, ed Palik, V1, ISBN 0-12-544420-6 (2) Li, Refractive Index of Germanium etc, J.Phys Chem, V9, p561, 1980 In addition, for the purposes of simulation, we have also introduced an optical phase shifter. Even though the refractive index of SiN is lower than that of silicon, it provides a good optical confinement (˘60-80%) with the advantage of having a higher tolerance to surface Silicon is widely used as an optical material in macroscopic and microscopic opto-mechanical applications.
The Orthogonal ID is used by INTERCONNECT to uniquely identify modes and it is important that this value be set correctly. Silicon has a further pass band 30 to 100 microns which is effective only in very high resistivity uncompensated material. In addition, we use S parameter objects to represent grating couplers. This circuit contains a basic Mach-Zehnder setup. xڝZK�ܶ��W�%nE����l˲�*�i+9����pwX�c�#Y�!=�u7���"ٗ�h ������v��g��>{�*Jv��'A��}�屗�]�g�Ż����ys��&6N�ܸA;����0t=ut��~��c8�(�cՎ�H�b���kR�G��P���ӡ����?�&�˱�P �Ż������_�Jw���a�C�ya��\�E���jk��d�`��c�Ǻ}ލE�^Ff��q��IB6O���ܹayQlvn`��2aj�a�q�(u�{�ƍ��yٝx%P�C���� 2*�B��]5u�磴�j.��b�����$��*�F�:�cQ�]�z�t�:�|�O��� ��6���);=N4����}g�(��y��b����M�ڱ��]K�T{]dqT�����R����������z r#��8VGe���W:�.���)�����+���S B���T��IN�:~���aK��u���N7���C�.�S}�ޏs���Jo+�T�z��p����y&��d��2��}���s�p�N5��� If we visualize in the same visualizer, we will see the figure below. rg���� F���~�J#�� =�2�t �oЋAK��.�c1(�ޣ��Ȅ������5���ܸ���B Once complete, which takes only about a second, we can visualize the transmission of the TM mode, remembering to plot the absolute value squared of this result.
The variable x1 represents T = (T-295K). If the file exists, choose to overwrite it. The waveguide is constructed in biosensor_waveguide.lms, and the fundamental TM mode at 1550nm is shown below.
Because fused silica is optically stable and consistent, many use it as a reference or standard for spectroscopic measurements. Therefore this system could detect a change in refractive index in the 30nm above the waveguide surface of 6e-5. In fact if the refractive index value at 1310 nm is 1.47x, the refractive index value at 1550nm will be 1.47y. 2, 105-117 (1993) Data [CSV - comma separated] [TXT - tab separated] [Full database record] Optical transmission calculator.
More importantly, we can plot the absolute value squared of the transmission at the center frequency, which is what an integrated photodiode would measure if a cw laser were used as a source. However, operation in the near infrared band beyond about 1200 nm provides a sufficiently low optical … Generally the optical fibers are divided into two in terms of refractive index, as the ones having graded index profile and the ones having step index profile. The sensitivity could be increased by increasing the length of the second arm but this can also cause additional problems with thermal stability.
The photodiode readout must be able to measure changes of 1/1000th of the dynamic range. 9N�:�>V���C��(���"!�9���)A(]9�6��&~[��+�!��ũ�m��c7!U��D��.=���x��}�t��7�#4V(T�P(�`p�8v���+�����m[��2n��ʔ�d"u We are now ready to proceed to the circuit simulation. As the analyte binds to the surface of the waveguide, the detector response will increase or decrease, and the change in output intensity can be calibrated to measure the change in refractive index above the waveguide and therefore the concentration of analyte.
Each material in the database has refractive index listed as a function of wavelength over a range typically required for thin-film thickness measurement. We can run this simulation by pressing the run button. Photonic integrated circuits - Circuits - list of examples, Optical QPSK + Electrical 16QAM transceiver, The chemistry required to functionalize the waveguide surface. Glass codes 7979, 7980, and 8655 are high purity non-crystalline silica glasses with excellent optical qualities. We then calculate the mode at 1500nm and perform a frequency sweep from 1500nm to 1600nm while tracking the TM mode. We can see that the TM mode is a good choice because the electric field is very intense precisely where the analyte will be bound to the waveguide surface. The Mach-Zehnder output would need to be fed into an integrated photodector. The arms of the interferometer are different lengths: the reference arm is only 100 microns long, while the sensing arm is 1mm long. The challenges with building this devices are. This waveguide supports 3 guided modes: 2 TE-like modes and 1 TM-like mode. These are analytic materials where the refractive index is set to be n(1550nm) + dn/dT*x1. If we want to calculate the temperature dependence of the effective index, we can change the silicon material to be "Si with T dependence" and the glass to be "SiO2 with T dependence".
As shown below, we should check the "detailed dispersion calculation" check box as well as the "store mode profiles while tracking" check box since these are required for export to INTERCONNECT. Silicon might also be an attractive high-refractive index material for the dielectric mirror coatings.
These are analytic materials where the refractive index is set to be n(1550nm) + dn/dT*x1. You will then see the window below. The text file that determines the change in effective index as a function of analyte refractive index was also created in the previous step and is imported into the phase shifter. We offer many different grades of fused silica to support various product applications.