This guide is for general information only and is not legal advice. Laws change — verify current rules with your state DOT or a licensed attorney before relying on this for any legal matter. Read full disclaimer.
The rule
Louisiana requires lamp on the front emitting a white light visible from a distance of at least 500 feet to the front, required between sunset and sunrise. For the rear, red reflector on the rear of a type approved by the department of public safety, visible from all distances from 100 feet to 600 feet when directly in front of lawful lower-beam headlamps. a red rear lamp visible from 500 feet may be used in addition to the reflector. The rule applies whenever it is dark. See La. R.S. 32:329 (Lamps and other equipment on bicycles).
The cheapest way to stay legal in Louisiana is a USB-rechargeable front white light and a rear red light or reflector that meets the spec above. A $30 light set covers it.