A method to produce in-situ steam comprising the steps of producing a laser beam in a steam generator segment positioned in a wellbore in a formation; introducing the laser beam to an activated carbon container, where the activated carbon container comprises activated carbon; increasing a temperature of the activated carbon with the laser beam to produce a hot activated carbon; introducing water to the activated carbon container through a water supply line; producing steam in the activated carbon container when the water contacts the hot activated carbon; increasing pressure in the activated carbon container as steam is produced until a pressure set point of an inter-container valve is reached; releasing steam through the inter-container valve to a steam container; increasing a pressure in the steam container until a release set point of one or more release valves is reached; and releasing steam through the release valve to the formation.