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Outline

Title
Abstract
Figures
Introduction
Prototype and Experimental Results
Improved Design Progress
Conclusions
References
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Physics
Optics

Ultrafast all-optical switching

Profile image of Nadav CohenNadav Cohen

2002

Abstract

We present innovative concepts related to the realization of ultrafast optical switches to be used for obtaining all-optical switching. We review the construction and the achievements of Civcom Incorporated during its research and development stages of constructing its ultrafast switch. Experimental measurements are exhibited.

Figures (20)
Fig. 2. 2 x 2 bypass exchange switch based on polarization coding with birefri- ngent calcite crystals as BDPs and FLC 2/2 retarder switch.
Fig. 2. 2 x 2 bypass exchange switch based on polarization coding with birefri- ngent calcite crystals as BDPs and FLC 2/2 retarder switch.
Fig. 4. Generalized 2 x 2 broadcast and switching system.
Fig. 4. Generalized 2 x 2 broadcast and switching system.
Fig. 3. Proposed setup for the 2 x 2 broadcast switch. (FLC) pixel and is reopened by the second calcite BDP2. When a proper voltage is applied to the FLC pixel, it acts as a A/2 pixel and the polarization of the signals A and B interchange, thus obtaining an exchanged state of the inputs in the output plane. With no voltage applied, the FLC is transparent to the incoming signals and the output is identical to the input (bypass mode). The final 2/2 plate in the output plane restores the output polarization of the second beam. A similar approach is used to achieve the 2 x 2 broadcast switch (Fig. 3).
Fig. 3. Proposed setup for the 2 x 2 broadcast switch. (FLC) pixel and is reopened by the second calcite BDP2. When a proper voltage is applied to the FLC pixel, it acts as a A/2 pixel and the polarization of the signals A and B interchange, thus obtaining an exchanged state of the inputs in the output plane. With no voltage applied, the FLC is transparent to the incoming signals and the output is identical to the input (bypass mode). The final 2/2 plate in the output plane restores the output polarization of the second beam. A similar approach is used to achieve the 2 x 2 broadcast switch (Fig. 3).
Fig. 5. All-optical 16 x16 switch. SLM, spatial light modulator. A demonstrator based on the design guideline stated in Section 2 was constructed. The light source used is a doubled Nd:Y ag laser (530-nm wavelength). An input mask was placed at the input plane. The constructed switch is a 16 x 16 switch consisting of 2 x 2 modules. The device is depicted in Fig. 5 where the optical core itself occupies a volume of less than 3 cm®. The state of each FLC controls the operation of the switch bypass, exchange, or broadcast. The panels are driven by dedicated hardware, which is computer controlled.
Fig. 5. All-optical 16 x16 switch. SLM, spatial light modulator. A demonstrator based on the design guideline stated in Section 2 was constructed. The light source used is a doubled Nd:Y ag laser (530-nm wavelength). An input mask was placed at the input plane. The constructed switch is a 16 x 16 switch consisting of 2 x 2 modules. The device is depicted in Fig. 5 where the optical core itself occupies a volume of less than 3 cm®. The state of each FLC controls the operation of the switch bypass, exchange, or broadcast. The panels are driven by dedicated hardware, which is computer controlled.
The experiment shown in Fig. 7 presents the polarization rotation ability of the new material. The figure depicts the first x/2 behavior of the material as a function of normalized voltage. As can be seen from the graph, the material has a linear behavior between the square of the operating voltage and the rotation of the polarization angle. This linearity starts from a certain voltage and greater. This behavior might be explained when we consider that the material exhibits a basic (natural) birefringence that exists when no voltage is applied to the device.
The experiment shown in Fig. 7 presents the polarization rotation ability of the new material. The figure depicts the first x/2 behavior of the material as a function of normalized voltage. As can be seen from the graph, the material has a linear behavior between the square of the operating voltage and the rotation of the polarization angle. This linearity starts from a certain voltage and greater. This behavior might be explained when we consider that the material exhibits a basic (natural) birefringence that exists when no voltage is applied to the device.
Fig. 7. Rotation of polarization angle (a) versus the square of the voltage.
Fig. 7. Rotation of polarization angle (a) versus the square of the voltage.
where A is the illuminating wavelength, V is the applied voltage, and V,(A) is the voltage (which is wavelength dependent) required for rotating the polarization angle in angle of m. This effect itself results from the imposed electric field that causes the asymmetric molecules of the material to align with the field. This causes the material to become anisotropic and birefringent. The change in the refraction index is given by
where A is the illuminating wavelength, V is the applied voltage, and V,(A) is the voltage (which is wavelength dependent) required for rotating the polarization angle in angle of m. This effect itself results from the imposed electric field that causes the asymmetric molecules of the material to align with the field. This causes the material to become anisotropic and birefringent. The change in the refraction index is given by
In addition to the operating rate mapping, various additional experiments were performed. For instance, for exploring the thermal dependence. The polarizers were in a cross state, and V3,, V2,, Vx were measured between 25 and 100 °C. Note that V,, denotes the normalized voltage required for obtaining an « rotation of the polarization angle with respect to V,, at 25 °C. The measurement was of the actual optical power impinging at the optical detector. No modulation was applied, and only dc voltages were used. Figure 10 presents the obtained results where the y-axis values were normalized to the voltage that was required at 25 °C.
In addition to the operating rate mapping, various additional experiments were performed. For instance, for exploring the thermal dependence. The polarizers were in a cross state, and V3,, V2,, Vx were measured between 25 and 100 °C. Note that V,, denotes the normalized voltage required for obtaining an « rotation of the polarization angle with respect to V,, at 25 °C. The measurement was of the actual optical power impinging at the optical detector. No modulation was applied, and only dc voltages were used. Figure 10 presents the obtained results where the y-axis values were normalized to the voltage that was required at 25 °C.
Fig. 10. Thermal dependence of the operation voltage for (a) V,, (b) V2, and (c) Vine
Fig. 10. Thermal dependence of the operation voltage for (a) V,, (b) V2, and (c) Vine
Fig. 11. Cross-talk demonstration in the 1 x 2 all-optical improved prototype.
Fig. 11. Cross-talk demonstration in the 1 x 2 all-optical improved prototype.
Fig. 12. Civcom’s improved 1 x 2 switching prototype.
Fig. 12. Civcom’s improved 1 x 2 switching prototype.
Fig. 13. Development of special electrical driver providing induced optical response with rise time and fall time of 250 ns.
Fig. 13. Development of special electrical driver providing induced optical response with rise time and fall time of 250 ns.
Fig. 15. Temperature cycling chamber testing. Fig. 14. Optical performance of the improved 1 x 2 switching prototype: (a) Insertion loss, (b) cross talk, (c) PDL, (d) PMD.
Fig. 15. Temperature cycling chamber testing. Fig. 14. Optical performance of the improved 1 x 2 switching prototype: (a) Insertion loss, (b) cross talk, (c) PDL, (d) PMD.
Fig. 16. Temperature cycling chart. In Fig. 17(a) the switch is mounted on an electrodynamic shaker. The sine vibration test graph is seen in Fig. 17(b). Figure 18 presents the switch mounted on the shock machine.
Fig. 16. Temperature cycling chart. In Fig. 17(a) the switch is mounted on an electrodynamic shaker. The sine vibration test graph is seen in Fig. 17(b). Figure 18 presents the switch mounted on the shock machine.
Fig. 19. Mechanical shock test graph. This paper has reviewed the research and development stage of Civcom Incorporated in which, it is believed, the first ultrafast all-optical switch was developed. Experimental results of the designed prototype were demonstrated. Further improvements are to be obtained at Civcom in the near future.
Fig. 19. Mechanical shock test graph. This paper has reviewed the research and development stage of Civcom Incorporated in which, it is believed, the first ultrafast all-optical switch was developed. Experimental results of the designed prototype were demonstrated. Further improvements are to be obtained at Civcom in the near future.
The mechanical shock test graph is seen in Fig. 19. Table 1 presents a measured datasheet of Civcom’s present technical performance for 1 x 2 and 2 x 2 switches, as discussed in this paper.
The mechanical shock test graph is seen in Fig. 19. Table 1 presents a measured datasheet of Civcom’s present technical performance for 1 x 2 and 2 x 2 switches, as discussed in this paper.
Table 1. Technical Specifications of Civcom’s Switch
Table 1. Technical Specifications of Civcom’s Switch

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References (4)

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  2. D. Mendlovic, B. Leibner, and N. Cohen, "Multistage optical system for broadcasting and switching information," Appl. Opt. 38, 6103-6110 (1999).
  3. D. Marom and D. Mendlovic "All-optical reduced state 4 by 4 switch," Opt. Photon. News (July, 1996), p. 43.
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