Micron-scale Raman amplifier: another progressive step towards the maturity of silicon photonics

Abstract

Notice of redundant publication "Micron-scale Raman amplifier: another progressive step towards the maturity of silicon photonics" It has been brought to the attention of the editors that this article contains redundancies when compared with an earlier article published by the authors in Datta T and Sen M 2017 Superlattices Microstruct. 109 107–16. The original article was not referenced. These concerns were identified after the article appeared as accepted but before publication of the final version. As a member of COPE this was been investigated in accordance with the COPE guidelines and it was agreed a notice of redundant publication should be applied. A new model for micron scale all-silicon amplifier has been proposed based on stimulated Raman scattering (SRS) in a slotted photonic crystal waveguide (SPCW). Silicon nanocrystal material is considered to be embedded in the slot of the SPCW to exploit its giant Raman gain coefficient. Moreover, the gain has further been enhanced by using the ultra-high optical confinement of the SPCW. Results of simulations show that the threshold power of a 3 μm long SPCW based Raman amplifier is in the order of merely 500 μW, while the CW Stokes is launched with a power of 50 μW. The simulations also show that a merely 1.5 μm long SPCW can offer ≈3 dB gain even at the 400 Gbps pulse repetition rate. However, pulse shape becomes disrupted by the SRS induced temporal broadening which has further been reduced considerably by operating the Stokes at a different resonance peak in the SRS gain spectrum. With these tremendous performances, the SPCW based Raman amplifier proves its potentiality for application in on-chip optical interconnects and also opens up a pavement for realizing the long desired micron-scale all-silicon Raman laser.

All‐optical logic inverter for large‐scale integration in silicon photonic circuits

“…Section 2 is a ‐based SPCW, as described in [17, 18, 30], having a length of . The material is considered to be formed with an ∼1:10 volumetric proportion of Si to SiO 2 [25], which has a refractive index of 1.98 and a peak Raman gain coefficient of 438 cm/MW.…”

“…The material is considered to be formed with an ∼1:10 volumetric proportion of Si to SiO 2 [25], which has a refractive index of 1.98 and a peak Raman gain coefficient of 438 cm/MW. Here, the pump and signal should be able to co‐propagate inside the SPCW for SRS interaction that has been ensured from its dispersion diagram [17, 18]. The fundamental z ‐odd propagation band in terms of the normalised frequencies with respect to the corresponding normalised wave vectors accommodating both the pump and the Stokes modes inside the SPCW has been recalculated as in [17, 18] using the plane wave expansion technique [32], and is shown in Fig.…”

“…The distribution will subsequently be used for calculating the effective area for SRS interaction. The dispersion diagram is also used to calculate group indices and higher order dispersion coefficients (up to the third order) of the waves, and it has been found that the pump operates at a group index () of ∼4.4 while the signal operates at a group index () of ∼24 [17]. These higher values of the group indices ensure the ultra‐high optical confinement of light in the SPCW, which assists the giant SRS gain coefficient of the to tremendously enhance the SRS interaction.…”

“… Fundamental z‐odd band, confined within the continuum of allowed states, ensuring propagation of the pump and the Stokes as recalculated from [17, 18 ]. Inset shows the corresponding variation in terms of wavelength …”

“…Nevertheless, these limitations can be removed by further intensifying the SRS interaction using the slow‐light phenomenon inside a silicon nanocrystal embedded slotted photonic crystal waveguide (SPCW), which has been demonstrated by the authors in [17, 18]. SPCWs are potential waveguide geometries which offer ultra‐high optical confinement [19] and, thereby, explore myriad of electro‐optical and all‐optical functionalities reported recently [20–24].…”