An optical sensing system comprising: a tunable laser that generates light over a range of wavelengths corresponding to a tuning range of the tunable laser; and an optical sensor configured to be coupled to the tunable laser to receive at least a portion of the light, the optical sensor comprising an optical fiber including one or more cores, characterized in that, for each core of the one or more cores: the core is inscribed with a first micrograting (G2, G3) at a first grating location along a length of the core and a second micrograting (G2, G3) located at a second grating location along the length of the core, the first micrograting (G2, G3) has a length along the core of 10 μm to 100 μm, and a width of a spectrum of a reflection from at least one grating is larger than the tuning range of the tunable laser, wherein the at least one grating is selected from the group consisting of the first micrograting (G2, G3) and the second micrograting (G2, G3), and wherein the width of the spectrum of the reflection enables measurement of reflections for a predetermined range of strains to be measured by the optical sensor, the predetermined range of strains including a maximum strain that creates a wavelength shift greater than half of the tuning range of the tunable laser, and a portion of the spectrum of the reflection is within the tuning range of the tunable laser for the predetermined range of strains. a tunable laser that generates light over a range of wavelengths corresponding to a tuning range of the tunable laser; and an optical sensor configured to be coupled to the tunable laser to receive at least a portion of the light, the optical sensor comprising an optical fiber including one or more cores, characterized in that, for each core of the one or more cores: the core is inscribed with a first micrograting (G2, G3) at a first grating location along a length of the core and a second micrograting (G2, G3) located at a second grating location along the length of the core, the first micrograting (G2, G3) has a length along the core of 10 μm to 100 μm, and a width of a spectrum of a reflection from at least one grating is larger than the tuning range of the tunable laser, wherein the at least one grating is selected from the group consisting of the first micrograting (G2, G3) and the second micrograting (G2, G3), and wherein the width of the spectrum of the reflection enables measurement of reflections for a predetermined range of strains to be measured by the optical sensor, the predetermined range of strains including a maximum strain that creates a wavelength shift greater than half of the tuning range of the tunable laser, and a portion of the spectrum of the reflection is within the tuning range of the tunable laser for the predetermined range of strains. an optical fiber including one or more cores, characterized in that, for each core of the one or more cores: the core is inscribed with a first micrograting (G2, G3) at a first grating location along a length of the core and a second micrograting (G2, G3) located at a second grating location along the length of the core, the first micrograting (G2, G3) has a length along the core of 10 μm to 100 μm, and a width of a spectrum of a reflection from at least one grating is larger than the tuning range of the tunable laser, wherein the at least one grating is selected from the group consisting of the first micrograting (G2, G3) and the second micrograting (G2, G3), and wherein the width of the spectrum of the reflection enables measurement of reflections for a predetermined range of strains to be measured by the optical sensor, the predetermined range of strains including a maximum strain that creates a wavelength shift greater than half of the tuning range of the tunable laser, and a portion of the spectrum of the reflection is within the tuning range of the tunable laser for the predetermined range of strains. the core is inscribed with a first micrograting (G2, G3) at a first grating location along a length of the core and a second micrograting (G2, G3) located at a second grating location along the length of the core, the first micrograting (G2, G3) has a length along the core of 10 μm to 100 μm, and a width of a spectrum of a reflection from at least one grating is larger than the tuning range of the tunable laser, wherein the at least one grating is selected from the group consisting of the first micrograting (G2, G3) and the second micrograting (G2, G3), and wherein the width of the spectrum of the reflection enables measurement of reflections for a predetermined range of strains to be measured by the optical sensor, the predetermined range of strains including a maximum strain that creates a wavelength shift greater than half of the tuning range of the tunable laser, and a portion of the spectrum of the reflection is within the tuning range of the tunable laser for the predetermined range of strains.