B. K. Das

Bio: B. K. Das is an academic researcher from Indian Institute of Technology Kharagpur. The author has contributed to research in topics: Lithium niobate & Waveguide (optics). The author has an hindex of 1, co-authored 3 publications receiving 5 citations.

Fabrication and characterization of erbium-doped titanium-indiffused lithium niobate waveguides for an integrated-optic amplifier

Abstract: Erbium is doped into z-cut Lithium Niobate (LiNbO3) substrate by thermal diffusion from thin Er film. XPS, PL and reflection studies have been carried out in order to characterize the doped sample and to test the suitability for amplifying signal at the wavelength 1530 nm. Straight waveguides of different widths (10, 15 and 100 micrometer) have been fabricated on the Er-doped sample by Ti diffusion. Loss measurements for the Er:Ti:LiNbO3 waveguides have been done by using lasers of wavelengths 633 and 1300 nm.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Modeling of titanium-indiffused lithium niobate optical waveguide by variational method

Abstract: The optical properties oftitaniurn-indiffused lithiu,n niobate (Ti:LiNbO3) waveguides can be analysed by various methodslike effective index method, WKB method, finite element method, ,natrix method, BPM method, variational method, etc.Among these, the variational method offers a great advantage in estimating the important characteristics of Ti:LiNbO3optical waveguides by direct use ofcontrollable fabrication parameters with less computing time. The present work dealswith the assessment ofoptical properties ofTi:LiNbO3 wai'eguide, typically at 1.53 and 1.3 pn wavelengths, although themethod can be extendedfor other communication wavelengths within the range 0.6-1.6 1um. Our simulated results on modeprofile have been verified with the experimental data. Keywords :variational method, lithium niobate, mode profile, effective refractive index, waveguide.1. INTRODUCTION The theoretical analysis of the guided modes in titanium indiffused lithium niobate waveguide (Ti:LiNbO3), is required foroptimising the performance of integrated optical devices on LiNbO3 substrates, like electrooptic modulators/switches,

Simulation of Gain Characteristics of Erbium-Doped Titanium in-Diffused Lithium Niobate Optical Waveguide Amplifiers

Abstract: Theoretical analyses have been carried out in order to find out the various characteristics of erbium-doped titanium indiffused lithium niobate (Er:Ti:LiNbO3) optical amplifiers. The relevant coupled differential equations of pump and isgnal evolution are numerically evaluated in getting the small signal gain characteristics through computer simulation. The pump and signal wavelengths of amplifier are chosen as λp =1.48 fim and λ =1.53 μm respectively. The amplifier gain is found to be fairly influenced by the erbium diffusion conditions, viz., temperature, time and ambient, the intensity profiles of the pump and signal, the level of lau]nched pump power and the length of the waveguide, etc. The maximum gain is obtained as 26 dB for 100 mW pump power in case of 28 cm length of a typical Er:Ti:LiNbO3 waveguide amplifier. It is found that beyond 28 cm, the gain of the amplifier decreases with the increase of length. This is expected due to the reduction of population inversion resulting from the gradual enhancement of total absorption and scattering losses of the pump power with respect to the distance traversed.

Gain calculation in erbium-doped LiNbO3 channel waveguides by defining a complex index profile

Abstract: An analysis of erbium-doped titanium indiffused LiNbO3 channel waveguides under 1484-nm excitation is presented in terms of a complex refractive index profile under 1484-nm excitation (pump) to obtain modal gain and loss for signal and pump powers, respectively. Closed form analytical expressions for modal fields are used to define the complex index profile. The calculated gain characteristics are compared with available experimental results.

Diffusion and solubility of ion-implanted Nd and Er in LiNbO3

Abstract: For our studies of laseractive rare earth ions in dielectric optical waveguides we have implanted Nd and Er ions into x and zcut LiNbO3 single crystals. We show the recrystallization of the host and the rare earth diffusion during annealing. Nd and Er have different solubilities and different diffusion constants in LiNbO3. The solubility is strongly temperature dependent. The diffusion is substitutional fastest parallel to c-axis of the LiNbO3 crystal and characterized by an activation energy of approximately 3. 6 eV.

Effects of Gamma Irradiation on Erbium Indiffused Lithium Niobate Substrate

Abstract: The effects of γ-radiation on Erbium (Er) doped LiNbO3, subsrate are investigated by measuring the photoluminescence (PL) spectra at different radiation doses and by performing the x-ray diffraction (XRD) analysis before and after γ-irradiation. The PL spectra are found to change significantly with γ-irradiation of dose 11.46 rad or above, γ-irradiation effects both the C-and L-bands of the erbium spectra. XRD study reveals that γ-ray exposure of dose 15.62 rad leads to morphological modification of the surface, with the appearance of a strong (101) Er2O3 peak and a (104) LiNbO3, peak along with the (006) and other peaks.

Studies on erbium diffusion in lithium niobate

Abstract: Experimental work on the study of erbium (Er) diffusion and the characterisation of Er-diffused layers required to form waveguide amplifiers in LiNbO3 substrate is presented. The presence of active Er in the lattice of LiNbO3 is investigated using x-ray photoelectron spectroscopy (XPS), photoluminescence (PL) measurement, and spectroscopic reflectometry. The shift of XPS peaks confirms the oxidized state of Er. The PL spectrum shows a sharp peak at 1530-nm wavelength, indicating the 4I15/24I13/2 lasing transition of Er3+. The reflectance spectrum indicates absorption at ~980 and ~1500 nm.