Liquid crystal optical routing switch

Abstract

The design and experimental results of a new 2 x 2 optical routing switch based on liquid crystal is reported. The switch uses nematic liquid crystal for polarization beamsplitting and ferroelectric liquid crystal for polarization rotation. The polarization insensitive, broadcast capable, full duplex switch has a signal-to crosstalk ratio of ~20 dB, a switching speed below 250 micros and a measured insertion loss of 1.4 dB. We show that the basic 2 x 2 switch can be extended to form a N x N rearrangeable permutation network.

Highly efficient interconnection for use with a multistage optical switching network with orthogonally polarized data and address information

“…This is true for the two switches being considered here, an acousto-optic switch 3 and a ferroelectric liquid-crystal switch. 4 …”

“…4 The second switch has a higher switching speed, but it must be slightly modified to work with this network. Other types of switches may also work for this architecture.…”

“…This extra pair of SS-FLC's is not included in the switch described in Ref. 4. They are necessitated by the orthogonal polarization of the data and the address information for this network.…”

“…A pair of Fabry-Perot cavities exist within the ferroelectric switch 4 because each beam splitter is made of a pair of glass prisms sandwiching a passive nematic liquid-crystal 1NLC2 cell. The slight index mismatch between the glass and the liquid crystal forms the cavity.…”

Tunable retarder made of pentaprisms and liquid crystal

“…On the other hand, parallel alignment of nematic LC induces retardation; i.e., a polarization state of the incident beam turns to the linear, elliptic, or circular polarization depending on wavelength and birefringence of LC [72][73][74]. Tunable LC retarders have been used for fabricating optical switches and routers [75][76][77][78][79].…”