An integrated photonics chip, comprising: a photonics substrate; a laser source operatively coupled to the photonics substrate, the laser source operative to emit a light beam; a plurality of tunable optical filters on the photonics substrate, the tunable optical filters in optical communication with each other and with the laser source; a plurality of emitting grating couplers on the photonics substrate, the emitting grating couplers each respectively coupled to an output of one of the tunable optical filters, wherein each emitting grating coupler is configured to emit the light beam received from the output of the respective tunable optical filter into a region of interest in different directions; at least one receiving grating coupler on the photonics substrate, the receiving grating coupler configured to receive scattered light from the region of interest; and a passive optical filter array on the photonics substrate and in optical communication with the receiving grating coupler, the passive optical filter array configured to receive the scattered light from the receiving grating coupler, wherein the passive optical filter array comprises a plurality of optical notch filters operative for frequency selection and a plurality of optical detectors each respectively coupled to an output of one of the optical notch filters, wherein each of the optical notch filters is configured to pass the received scattered light at a corresponding wavelength range to a respective one of the optical detectors, wherein each corresponding wavelength range is distinct, wherein the passive optical filter array is operative to perform frequency spectrum decomposition of the received scattered light into a plurality of signals; wherein the light beam emitted from the laser source is routed to one or more of the tunable optical filters, which are operative to allow transmission of the light beam to one of the emitting grating couplers at any given time, such that the light beam is emitted into the region of interest at different times from each of the emitting grating couplers. a photonics substrate; a laser source operatively coupled to the photonics substrate, the laser source operative to emit a light beam; a plurality of tunable optical filters on the photonics substrate, the tunable optical filters in optical communication with each other and with the laser source; a plurality of emitting grating couplers on the photonics substrate, the emitting grating couplers each respectively coupled to an output of one of the tunable optical filters, wherein each emitting grating coupler is configured to emit the light beam received from the output of the respective tunable optical filter into a region of interest in different directions; at least one receiving grating coupler on the photonics substrate, the receiving grating coupler configured to receive scattered light from the region of interest; and a passive optical filter array on the photonics substrate and in optical communication with the receiving grating coupler, the passive optical filter array configured to receive the scattered light from the receiving grating coupler, wherein the passive optical filter array comprises a plurality of optical notch filters operative for frequency selection and a plurality of optical detectors each respectively coupled to an output of one of the optical notch filters, wherein each of the optical notch filters is configured to pass the received scattered light at a corresponding wavelength range to a respective one of the optical detectors, wherein each corresponding wavelength range is distinct, wherein the passive optical filter array is operative to perform frequency spectrum decomposition of the received scattered light into a plurality of signals; wherein the light beam emitted from the laser source is routed to one or more of the tunable optical filters, which are operative to allow transmission of the light beam to one of the emitting grating couplers at any given time, such that the light beam is emitted into the region of interest at different times from each of the emitting grating couplers.