Abstract: “High-sensitivity laser-based sensors have attracted much interesting for their significant applications in biological applications. In this work, the concept of laser-based detector fabricated by using optical fiber for detection of the hemoglobin concentration in the human blood was proposed. The laser biosensor is based on Mach-Zehnder interferometer (MZI) (micro-holes collapsing) which exhibits high sensitivity changing in the hemoglobin concentration of the blood sample. This sensor measures the reduction in the intensity of light from the laser source. By using this sensor, two drops of human blood sample are sufficient to detect the concentration of the hemoglobin. Green laser with wavelength of 532 nm and input power of 12.2 nw has been used. A calibration curve between the absorbance of the green laser by the blood sample and the hemoglobin concentration was obtained to find the hemoglobin concentration for any blood sample which has the refractive index in the range between (1”

Keywords: Laser biosensor, Photonic crystal Fiber