Bistable light switching

The authors have applied polymer/LC composite films as novel permselective membranes [1-8]. The polymer/LC composite film exhibited a distinct and rapid light switching between turbid and transparent states upon off- and on-a.c. electric fields, respectively [9-13]. Also, we proposed a novel type of reversible and bistable light switching by the use of the LCP/LC composite system[l4,15]. 

Bistable Light Switching of the PCPHS/CPHOB Composite System... 

In this paper, the phase transition behavior, aggregation states, and also, a bistable and reversible light switching behavior based on light scattering have been investigated for the ternary (LCP/LC2/LC1) composite system in an induced smectic phase. 

Mirrorless optical nonlinear effects (optical bistability, optical switching, and transient grating nonlinearity) as mentioned above, were observed only in dye-doped CLCs. In nonabsorbing CLCs, the realization of the light-induced pitch dilation became possible when it was used in optical schemes as a mirror. 

Of much interest are the electroluminescence properties of conjugated polymers that allow the development of electrically switched light-emitting devices [8.257]. Electric field activated bistable molecules are expected to switch at a critical field strength [8.258]. 

In solid state all the 10 pyroelectric crystal groups allow in principle for bistable switching behaviour. This is the proper ferroelectricity. Under certain conditions ferroelectricity (improper) can be realized in liquid crystals. This was shown by Meyer and coworkers115 in 1975. Since that time intense activities have been initiated, applying this property for flat-panel devices, switches, light modulators etc. In principle, three effects can be observed and used ... 

So far, several example of the chemically and electrochemically controlled switching of bistable linear molecular machines have been presented. The final section of this chapter will be dedicated to illustrating how such molecular switches and motors, when designed ingenuously, can also be powered by nature s most abundant and powerful energy source - light. 

The preparation of chiral magnetic materials is not limited to those that show paramagnetism and magnetic ordering. Another important phenomenon is that of spin crossover, as it can lead to bistable systems, that in addition can be switched by light [213,214]. A homochiral spin crossover... 

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