The design for an all optical XOR gate is proposed. The basic idea is to split the input beams and let them cancel
or strengthen each other selectively or flip the encoded information based on their polarization properties. The
information is encoded in terms of polarization of the beam. Polarization of a light beam is well understood hence
the design should be feasible to implement. The truth table of the optical circuit is worked out and compared
with the expected truth table. Then it is demonstrated that the design complies with the linear behavior of the
XOR function. In the next section, based on a similar idea, the design of an all optical CNOT gate is proposed.
The truth table for the gate is verified. Then, it is discussed how this approach can be used for Linear Optics
Quantum Computation (LOQC). It is shown that with a Hadamard gate and a rotation gate, the CNOT gate
makes up a universal set of quantum gates based on linear optics. This novel approach requires no additional
power supply, extra input beam or ancilla photon to operate. It also doesn't require the expensive and complex
single photon source and detector. Only narrowband laser sources are required to operate these gates.
A new design of a variable mechanical optical attenuator is proposed in this paper. Mechanical attenuators are
extensively important in designing optical communication systems. It is also highly used in testing and training
purposes. The design consists a novel fiber optic splitter-combiner setup. Each branch of the splitter meets
a specific branch of the combiner. A fixed distanced multi-window rotary wheel slides between them. Upon
rotation the light is either blocked or allowed to pass from a splitter branch to a combiner branch. By changing
the number of open gates, the amount of yielded light can be controlled. There is only one moving part. So,
the design is easy to manufacture, use or repair. The basic design and work flow is explained. The formula for
calculating the attenuation and calibration guideline is also discussed. Then the design is compared with the
other design standards based on the areas of application. The possible effects of linear and non-linear properties
of light is also discussed. The primary concerns that should be taken if this design is to be fabricated in photonic
integrated circuits is also mentioned briefly.