A. Bhargava

TUNABLE WAVELENGTH DEMULTIPLEXER FOR DWDM APPLICATION USING 1-D PHOTONIC CRYSTAL

Transmission characteristics of 1-D photonic crystal (PC) structure with a defect have been studied. We consider a Si/ZnS multilayer system. We also consider the refractive index of both layers to be dependent on temperature and wavelength simultaneously. The refractive indices of Si and ZnS layers are functions of temperature as well as of the wavelength of incident light. This property can be used to tune the defect modes at desired wavelength. As defect modes are function of temperature, one can tune the defect modes to desired wavelength. It is found that the average change in central wavelength of each defect mode is 0.07nm/K. This property can be exploited in the design of a tunable wavelength demultiplexer for DWDM application in optical communication.

THERMAL EXPANSION OF PHOTONIC BAND GAP FOR ONE DIMENSIONAL PHOTONIC CRYSTAL

The efiect of temperature on the photonic band gap has been investigated. One dimensional photonic crystal in the form of Si/air multilayer system has been studied in this communication. The refractive index of silicon layers is taken as a function of temperature and wavelength both. Therefore, this study may be considered to be physically more realistic. It may be useful for computing the optical properties for wider range of wavelength as well as temperature. We can use the proposed structure as temperature sensing device, narrow band optical fllter and in many optical systems.

TUNABLE MULTI-CHANNEL FILTERING USING 1-D PHOTONIC QUANTUM WELL STRUCTURES

In the present study, we show that it is possible to achieve multi-channel fllters in one-dimensional photonic crystals using photonic quantum well structures. The photonic quantum well structure consists of difierent 1-D photonic structures. We use (AB)8/Cn/(BA)8 structure, where A, B and C are difierent materials. The number of defect layers (C) can be utilized to tune the multi- channel flltering. The fllter range can be tuned for desired wavelength with the change in angle of incidence for multi-channel flltering.

Temperature-Dependent Tunable Photonic Channel Filter

In the present communication, we studied the 1-D photonic quantum-well (PQW) structure for the photonic channel filter. The PQW structure consists of a defect layer in Si/air multilayered regular 1-D photonic crystal. The extension of the work shows the temperature-dependent tuning in the channel filter.

Wide Range Temperature Sensors Based on One-Dimensional Photonic Crystal with a Single Defect

Transmission characteristics of one-dimensional photonic crystal structure with a defect have been studied. Transfer matrix method has been employed to find the transmission spectra of the proposed structure. We consider a Si/air multilayer system and refractive index of Si layer has been taken as temperature dependent. As the refractive index of Si layer is a function of temperature of medium, so the central wavelength of the defect mode is a function of temperature. Variation in temperature causes the shifting of defect modes. It is found that the average change or shift in central wavelength of defect modes is 0.064 nm/K. This property can be exploited in the design of a temperature sensor.

Silicon Based One-Dimensional Photonic Crystal as a TM-Mode Filter

The effect of temperature and angle of incidence on the transmission spectra of a one dimensional photonic crystal for TE and TM polarizations has been studied. For a range of angle of incidence from 0° to 60°, the proposed structure works as an omni-directional reflector. For other angles of incidence more than 60°, the structure works as a selective TM-polarization filter i.e. a filter which completely blocks TE-polarized waves but allows certain frequencies of TM-polarized waves. At an angle of incidence of 89°, the structure works as a multi channel optical filter without introducing any defect in the geometry. Also, this multi-channel filter can work as a tunable filter by varying the temperature of the structure and the number of layers in the geometry. Only for two bi-layers the proposed structure works as a single channel filter. Therefore, such types of structure are easier to fabricate and may be cost effective as compared to defect one-dimensional photonic crystals.

Optical Properties of Plasma Photonic Crystals

In the present communication, the optical properties of a one-dimensional plasma photonic crystal (PPC) containing alternate dielectric and plasma layers has been studied. The photonic band structure, reflection spectra and group velocity of such photonic crystals have been presented. It is found that the photonic bandgap can be increased with the thickness of plasma layers and group velocity reaches negative values at a certain frequency.