Table 2.

The comparison table of the evaluated $\beta$ and $n_2$ values of the present study and previous reports on other oxide and NiO.

Sample	$\beta$ (cm ${\text{W}}^{-1}$)	$n_2$ (${\text{cm}}^2$ ${\text{W}}^{-1}$)	Parameters	References
Ni-doped ZnO thin film	$2.80-4.28\times$ ${10}^{-7}$	$4.04-4.78\times$ ${10}^{-11}$	$\lambda =750$ nm	42
170 nm thick ITO thin film	–	$9.0\times$ ${10}^{-12}$	$\lambda =820$ nm	43
As deposited NiO films	–	$9.4-8.8\times$ ${10}^{-7}$	$\lambda =632.8$ nm	14
250 °C annealed NiO films	–	$2.3-3.3\times$ ${10}^{-5}$	$\lambda =632.8$ nm	14
NiO microrods	$3.5\times$ ${10}^{-9}$	–	$\lambda =532$ nm	44
NiO-PVA composite film	$1.30-3.39\times$ ${10}^{-6}$	–	$\lambda =532$ nm	45
Undoped NiO films	$0.92\times$ ${10}^{-5}$	$2.2\times$ ${10}^{-12}$	$\lambda =532$ nm	16
N-doped (20% Ar, 80% N$_2^{}$) NiO films	$4.55\times$ ${10}^{-5}$	$6.5\times$ ${10}^{-12}$	$\lambda =532$ nm	16
Undoped NiO films	$9.01\times$ ${10}^{-2}$	$8.36\times$ ${10}^{-9}$	$\lambda =632.8$ nm	21
15% N in NiO films	$5.32\times$ ${10}^{-2}$	$6.35\times$ ${10}^{-7}$	$\lambda =632.8$ nm	21
NiO films	$6.60\times$ ${10}^{-7}$	$0.2\times$ ${10}^{-10}$	$\lambda =800$ nm	17
Pristine NiO	$-6.66\times$ ${10}^{-6}$	$2.68\times$ ${10}^{-10}$	$\lambda =1030$ nm	This work
300 °C annealed	$9.23\times$ ${10}^{-6}$	$1.99\times$ ${10}^{-10}$	$\lambda =1030$ nm	This work
350 °C annealed	$9.86\times$ ${10}^{-6}$	$1.64\times$ ${10}^{-10}$	$\lambda =1030$ nm	This work
400 °C annealed	$19.08\times$ ${10}^{-6}$	$4.21\times$ ${10}^{-10}$	$\lambda =1030$ nm	This work
450 °C annealed	$17.08\times$ ${10}^{-6}$	$4.11\times$ ${10}^{-10}$	$\lambda =1030$ nm	This work
500 °C annealed	$0.89\times$ ${10}^{-6}$	$0.92\times$ ${10}^{-10}$	$\lambda =1030$ nm	This work