Design of highly nonlinear dispersion flattened hexagonal photonic crystal fibers for dental optical coherence tomography applications

Abstract

In this paper, we propose a highly nonlinear dispersion flattened hexagonal photonic crystal fiber (HNDF-HPCF) with nonlinear coefficients as large as 57.5 W À1 km À1 at 1.31 m wavelength for dental optical coherence tomography (OCT) applications. This HNDF-HPCF offers not only large nonlinear coefficient but also very flat dispersion slope and very low confinement losses. Using these characteristics of our proposed PCF, it is shown through simulations by using finite difference method with an anisotropic perfectly matched boundary layer that this PCF offers the efficient supercontinuum (SC) generation for dental OCT applications at 1.31 m wavelength using a picosecond pulse easily produced by commercially available less expensive laser sources. Coherent length of light source using SC is found 10 m and the spatial resolutions in the depth direction for dental applications of OCT are found about 6.

Near Infrared Supercontinuum Generation in Silica Based Photonic Crystal Fiber

“…Comparison is also made between the proposed HN-PCF, particularly at the centre wavelength values of 1.0 µm, 1.30 µm and 1.55 µm, and other fibers available in the literature [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] in terms of coherent power. This comparison is depicted in Table 3, showing fabricated fiber materials, center wavelength and coherent powers of the different optical fibers considered.…”

“…It should be highlighted that all the fibers considered are doped fibers with the exception of the fibers in [8,[24][25][26] and the proposed HN-PCF in this paper. It can be clearly seen from the table that the proposed HN-PCF achieves higher power values than other fibers [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Furthermore, the proposed HN-PCF is un-doped and hence, is relatively easier to fabricate than doped fiber.…”

“…Various supercontinuum (SC) generated highly nonlinear photonic crystal fibers (HN-PCFs) have been reported in the literature for optical communications and medical applications [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22], using different materials to produce broadband SC spectrum with varying performances.…”

“…Different designs of femtosecond (fs), picosecend and nanosecond pulse laser sources are proposed and consequently, investigated in references [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. In [10], the authors investigate the performance of femtosecond-laser pulses in neodymium-doped yttrium aluminium garnet (Nd:YAG) crystals and report that output power of around 1.3 W at around 1.0 µm center wavelength is achievable from an 2.25 W launched pump power.…”

“…Using a laser source with a peak power of 4.4 kW, an ultra-broadband SC spectrum may be generated at 1.55 µm wavelength, by using germanium doped core fiber [19]. Similarly, Ge-doped PCF picosecond pulse laser with 10 W input peak power is investigated in [20], to produce broadband SC spectrum at the 1.31 µm center wavelength.…”