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In this paper, we design a silicon nanowire embedded photonic crystal fiber (SN-PCF) using fully vectorial finite element method. Further, we analyze the various optical properties, namely, waveguide dispersion and nonlinearity by varying the core diameter from 400 to 500 nm for a wide range of wavelengths from 0.8 to 1.7 µm. The proposed structure exhibits a low second (-0.4909 ps 2 /m) and third order (0.6595 10 −3 ps 3 /m) dispersions with very high nonlinearity (1358 W −1 m −1 ) for 480 nm core diameter at 0.8 µm wavelength. Besides, we investigate the evolution of supercontinuum at 0.8 µm, 1.3 µm and 1.55 µm wavelengths for an incredibly low input pulse energy of 2.5 pJ. The numerical results corroborate that the proposed SN-PCF provides a wider supercontinuum bandwidth of 1250 nm at 0.8 µm, 1100 nm at 1.3 µm and 800 nm at 1.55 µm wavelengths. We demonstrate longitudinal resolution of 0.16 µm at 0.8 µm wavelength for ophthalmology and dermatology, 0.41 µm at 1.3 µm wavelength for dental imaging and 0.8 µm at 1.55 µm wavelength also for dental imaging. To our knowledge, these are the highest resolution ever achieved in biological tissue at 0.8 µm, 1.3 µm and 1.55 µm wavelengths.

In this paper, we generate bright as well as dark soliton type ultrashort laser pulses in a photonic nanowire. The pulse evolution in the photonic nanowire is described by higher order nonlinear Schrödinger equation with an additional effect relating to the nonlinear change of group velocity, which, in turn, is proportional to the field intensity. The pulse evolution equation is solved by coupled amplitude-phase method. Further, we calculate the minimum power required for realizing the ultrashort laser pulses. The main crux of this work stems from the generation of ultrashort pulses by an entirely new nonlinear effect involving change of group velocity.