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ALT'23 The 30th International Conference on Advanced Laser Technologies
P-O-5
Cascading of logic gates based on Y shaped photonic crystal
waveguide
P. Mokshin1, D. Golovashkin1'2, V. Pavelyev1,2
1- Samara National Research University, Samara, Russia 2- Image Processing Systems Institute, Branch of the Federal Scientific Research Centre "Crystallography and Photonics " of
Russian Academy of Science, Samara, Russia
A further step in the development of photonic digital computing devices is the combination of interference logic gates into one circuit [1] using some serial connections. Sequential realization of logical operations imposes a significant limitation on the phase of the gate output signal. The phase has to be determined. Note, that the issue of phase uncertainty does not preclude the use of logic gates. However, there are limitations that arise when trying to cascade them. The problem of phase uncertainty lies in the dependence of the phase of the gate output signal corresponding to the value 1 on the values of the operands of the logic gate of the type "OR", "NOR", "XOR", etc. An uncertain value of the phase of the output signal makes it impossible to cascade such elements. The supply of different-phase signals corresponding to 1 to the input of the logic gate of the next stage will lead to different results.
To solve this problem authors propose to exploit the basic fact of Boolean logic. "AND" and "NOT" operations are enough to form a minimal complete basis [2]. Any other logical operation can be expressed as their combination. It should be noted that "AND" and "NO" gates do not have the problem of phase uncertainty, so it is possible to design a logic gate for any logical operation without this problem. The Figure 1 proposes the implementation of "NOR" on the base of "AND" and "NOT" gates cascading. Ports A and B are the "NOT" inputs. C and D are inputs of the second element associated with the realization of "NOT" operation. E is the output of the combined "NOR" logic gate.
Fig. 1. Photonic crystal with three Y-shaped defects, which implements the logical operation «NOR». B and C are inputs for operand signals, A and
D are inputs for reference signals, E is an output for the operation result signal
The proposed logic gate (Fig.1) was studied in a series of numerical experiments. The signal that corresponds to "true" value at the E output is always has the same phase. It should be noted that the implementation of the logic gate (Fig.1) demonstrates the possibility of logic gates cascading.
[1] Hussein M.E., Tamer A. Ali, Nadia H. Rafat, New designs of a complete set of Photonic Crystal logic gates, Optics Communications, vol. 411, pp. 175-181, (2018)
[2] S. V. Yablonski, Introduction to Discrete Mathematics, (1986, In Russian)
