Abstract: A device for measuring the power and wavelength of laser radiation via the photoacoustic effect, includes a cell containing at least one gas having an absorption line with a central wavelength ?c, an electro-acoustic transducer arranged within the cell and suitable for generating a signal representative of the photoacoustic signal in the cell, means for processing the signal generated by the electro-acoustic transducer, wherein an estimate of the concentration of the one or more gases is stored, at least one laser source suitable for emitting, into the cell, laser radiation at a wavelength suitable for exciting at least one gas contained in the cell, the laser radiation having a wavelength that is variable in an oscillatory manner about an average wavelength ?moy at a modulation frequency (f1), such that an interaction between the laser radiation and at least one gas contained in the cell induces generation of a photoacoustic signal at a detection frequency of the electro-acoustic transducer, the cell being s

Abstract: Semiconductor laser chip (101) comprising A substrate (105) comprising: two lateral faces (107), an lower face (109), an upper face (108), at least two semiconductor lasers (102), these two lasers (102) being distributed between said two lateral faces (102) with a spacing (E) between two adjacent lasers (102), said substrate (101) having a width (I), this width being the distance between said two lateral faces (107) of the substrate (105), and a thickness (e), this thickness (e) being the distance measured between the lower face (109) and the upper face (108) of the substrate (105) perpendicular to the width (I), said width (I) being less than or equal to 4 times the thickness (e).

Abstract: A free-space optical communication system includes a transmitter and a receiver, the transmitter being configured to transmit an encrypted message to the receiver at the mid-infrared domain, the transmitter comprising a master mid-infrared optical source configured to generate a mid-infrared signal and a chaos generator configured to generate a chaotic signal by applying external optical feedback to the master mid-infrared optical source, the transmitter being configured to determine an encrypted message from an original message by applying a message encryption technique to the original message and to send the encrypted message to the receiver through an optical isolator, the receiver comprising a slave mid-infrared optical source similar to the master mid-infrared optical source the slave mid-infrared optical source being configured to recover the chaotic signal from the encrypted message by applying chaos synchronization, the receiver further comprising a first detector configured to detect the encrypted me

Abstract: A photo-acoustic gas sensor using a method for modulating the wavelength of the laser radiation, the modulation being obtained via judicious use of an electric current, called the generation current, which pumps the one or more laser sources, and is configured to cause the one or more laser sources to operate in pulsed mode, and of a current, called the base current, which takes non-zero values between each laser pulse with a lower magnitude than the magnitude of the generation current, the magnitude of base current being modulated so that the one or more laser sources emit, into the cell, light radiation having a wavelength that varies periodically about a central wavelength so as to take, at regular intervals, a value specifically suitable for the excitation of a gas to be detected, whereby an interaction between the light radiation and the gas to be detected contained in the cell induces the generation of acoustic waves at a resonant frequency of the cell.