Semiconductor Laser Chip for Gas Sensor

Abstract

Two side surfaces (107), a bottom surface (109), a top surface (108), and a substrate (105) including them; at least two semiconductor lasers (102), the two lasers (102) being spaced apart by a distance (E) between two adjacent lasers (102) and being distributed between the two side surfaces (102); and the substrate (101) having a width (l) which is the distance between the two side surfaces (107) of the substrate (105), and a thickness (e) which is the distance measured between the bottom surface (109) and the top surface (108) of the substrate (105) perpendicular to the width (l), the width (l) being not more than four times the thickness (e), a semiconductor laser chip (101).

Description

Technical Field

[0001] The present invention relates to the field of semiconductor lasers, and more particularly to semiconductor laser chips, especially semiconductor laser chips for gas sensors.

Background Art

[0002] Generally speaking, a semiconductor laser chip is obtained by a complex series of steps including depositing layers on a single-crystalline substrate (also referred to herein as a substrate) that forms a wafer, and cutting this wafer to obtain the laser chip. This layer deposition is performed by liquid-phase or vapor-phase epitaxy, or by molecular beam injection onto the substrate. The substrate is a pure crystal (usually InP or InAs or GaAs or other semiconductor materials). The laser unit is generally a parallelepiped portion of the wafer and is obtained by a series of chemical or physico-chemical etching and deposition steps of a material, which may be amorphous or crystalline, intended to form a laser cavity and a diffraction grating to structure the laser unit.

[0003] There are many different types of semiconductor laser chips including quantum laser cascade (QCL) chips. A quantum cascade laser chip includes two electrodes for applying an electric field between two electrodes, a waveguide disposed between the electrodes, and a gain region formed of a plurality of layers alternately including, for example, a first type of layer each defining a quantum barrier and a second type of layer each defining a quantum well, and these layers are made of first and second semiconductor materials constituting the barrier and the well, respectively. The quantum cascade laser unit also includes two optical confinement layers disposed on both sides of the gain region. The laser unit forms a rod that extends at least partially along the length of the semiconductor laser chip.

[0004] When a laser chip is manufactured, it is usually cleaved parallel to the bars formed by the laser units on the substrate. This determines the width of the laser chip. Then, to create the facets that function as mirrors, the laser chip is cleaved perpendicular to the bars. These cleavages involve breaking the substrate crystal on which the laser units are deposited along the crystal axis, i.e., the axis extending across the thickness of the substrate, in order to obtain a nearly perfect mirror surface. This breaking is generally achieved by scratching the surface of the substrate containing the laser units and then applying pressure on both sides of the scratch to break the crystal along this crystal axis.

[0005] The overall production cost of a semiconductor laser chip is defined, in particular, by the following formula, i.e., the surface area of the material used to manufacture the laser chip / the production yield of the semiconductor laser chip × the cost of manufacturing the cleaved laser chip.

[0006] The following is understood. The surface area of the material used is defined by the surface area of the material (substrate and deposited layer) used to manufacture the laser chip. The production efficiency of the semiconductor laser chip is defined by the ratio of the number of functional laser units to the maximum number of laser units that can be produced on the laser chip. The cost of manufacturing the cleaved laser chip corresponds to the cost of implementing the process used to manufacture the said laser chip.

[0007] Therefore, the larger the surface area of the material used, and / or the lower the production yield of the semiconductor laser chip, and / or the higher the cost of manufacturing the laser chip.

[0008] In the prior art, there are laser chips with a single laser unit. Such semiconductor laser chips have unoptimized production yields. This is because there is only one functioning laser unit and the surface area of the semiconductor laser chip is not fully utilized. In other words, a part of the laser chip surface is lost.

[0009] The prior art also includes semiconductor laser chips with several laser units each configured to emit a unique specific wavelength. For example, U.S. Patent No. 7826509 describes a laser chip typically having a plurality of laser units with a width of 2 mm. This shape is used in portable broadband sensors for simultaneously detecting a large number of chemical compounds. The use of such a large area of material is particularly costly.

Summary of the Invention

Problems to be Solved by the Invention

[0010] The present invention aims to reduce the overall production cost of semiconductor laser chips by maximizing the number of laser units on the smallest laser chip obtained by cleavage.

Means for Solving the Problems

[0011] In this specification, the terms chip, laser chip, and semiconductor laser chip are used interchangeably, the terms assembly and chip-based plate assembly are used interchangeably, and the terms laser unit and semiconductor laser unit are used interchangeably.

[0012] In this specification, certain elements or parameters, such as the first unit or the second unit, and the first parameter and the second parameter, or the first criterion and the second criterion, may be indexed. In this case, this is a simple indexing problem for distinguishing and naming elements or parameters or criteria that are similar but not identical. This indexing does not mean that one element, parameter, or criterion takes precedence over another, and such names may be easily exchanged without departing from the scope of this specification. This indexing also does not mean, for example, a chronological order for evaluating this or that criterion.

[0013] The present invention relates to a substrate, particularly a cleaved substrate, comprising two side surfaces, a bottom surface, and a top surface, and at least two semiconductor laser units, the two laser units being spaced apart between two adjacent laser units and distributed between the two side surfaces. The substrate has a width that is the distance between the two side surfaces of the substrate and a thickness that is the distance between the bottom surface and the top surface of the substrate perpendicular to the width of the substrate, and the width is not more than 4 times the thickness of the substrate. The present invention relates to a semiconductor laser chip.

[0014] In one aspect of the present invention, the laser chip is obtained by cleaving a substrate.

[0015] In one aspect of the present invention, the two side surfaces of the substrate are obtained by cleaving the substrate, and the substrate is particularly cleaved.

[0016] In one aspect of the present invention, the bottom surface and the top surface are two opposing surfaces of the substrate. The modifiers "lower side" and "upper side" are conventions for distinguishing these two surfaces.

[0017] In one aspect of the present invention, the two side surfaces are two opposing surfaces of the substrate.

[0018] The width means the distance between the two side surfaces of the substrate, and between these side surfaces, semiconductor laser units are dispersed with an interval between two adjacent laser units, that is, the laser units are arranged at different positions separated by the interval between two adjacent laser units in the width dimension of the substrate.

[0019] Here, the thickness refers to the distance between the lower surface and the upper surface of the substrate. The lower surface is configured to rest on the base plate, and the upper surface is on the opposite side of the lower surface.

[0020] The length means the distance between the other two surfaces of the substrate. These two surfaces are each in contact with any one of the two side surfaces, the lower surface, and the upper surface of the substrate, and the laser unit extends at least partially over these two surfaces.

[0021] In particular, the presence of at least two laser units in the laser chip means that substantially the entire surface area of the laser chip can be utilized. In other words, most of the surface area of the substrate, and thus of the laser chip, is not wasted. The laser units are dispersed over the entire width of the substrate such that a single chip comprises a plurality of laser units. This optimizes the production efficiency of the laser chip.

[0022] In one aspect of the present invention, the width of the laser chip is the same as the width of the substrate.

[0023] In one aspect according to the present invention, the substrate has a width that is 3.5 times or less, preferably 3 times or less, preferably 2.5 times or less, preferably 2 times or less, preferably 1.5 times or less the thickness of the substrate.

[0024] In this way, the surface area of the material used to produce the laser chip is reduced, leading to a reduction in the production cost of the laser chip. The width of the substrate of the semiconductor laser chip is large enough to prevent the laser chip from being damaged during the cleavage step that may break the chip. Therefore, the width / thickness ratio of this substrate gives the laser chip sufficient mechanical strength to avoid breakage during the cleavage step. Thereby, the smallest cleavable laser chip is obtained.

[0025] In one aspect according to the present invention, the width of the substrate is 150 μm to 1 mm, preferably 150 μm to 750 μm, more preferably 150 μm to 500 μm, more preferably 150 μm to 400 μm, more preferably 150 μm to 350 μm, more preferably 150 μm to 300 μm, more preferably 150 μm to 250 μm, more preferably 200 μm to 250 μm, and more preferably equal to 250 μm.

[0026] In one aspect according to the present invention, the thickness of the base material is 50 μm to 350 μm, preferably 75 μm to 300 μm, more preferably 100 μm to 200 μm, more preferably 100 μm to 150 μm, and more preferably 120 μm to 150 μm.

[0027] In one aspect of the present invention, the length of the substrate is 0.5 mm to 5 mm, preferably 1 mm to 3.5 mm, and more preferably 2 mm to 3 mm.

[0028] In one aspect of the present invention, the laser chip includes at least three laser units, and these three laser units are spaced apart between two adjacent laser units and are distributed between two side surfaces of the substrate. In other words, at least three laser units are distributed across the entire width of the substrate. In other words, at least three laser units are distributed across the entire width of the laser chip.

[0029] In one aspect of the present invention, the laser unit is arranged on one surface of the substrate.

[0030] In one aspect of the present invention, the laser unit is disposed on the lower surface of the substrate. In another aspect, the laser unit is disposed on the upper surface of the substrate.

[0031] In another aspect of the present invention, the laser unit is embedded in the substrate. In this aspect of the present invention, the laser chip includes at least one layer of electrically insulating material on both sides of the laser unit. The insulating material is, for example, semi-insulating InP (indium phosphide). The semi-insulating InP is, for example, so-called doped InP with impurities such as iron added. In this way, the laser units are electrically insulated from each other.

[0032] In one aspect of the present invention, the laser unit is closer to the upper surface of the substrate than to the lower surface of the substrate. This means that the laser unit is embedded in a substrate closer to the upper surface than the lower surface of the substrate, or that the laser unit is disposed on the upper surface of the laser chip substrate.

[0033] In one aspect of the present invention, the laser unit is closer to the lower surface of the substrate than to the upper surface of the substrate. This means that the laser unit is embedded in a substrate closer to the lower surface than the upper surface of the substrate, or that the laser unit is disposed on the lower surface of the substrate.

[0034] In one aspect of the present invention, the laser chip includes at least two electrodes of different polarities configured to allow current to flow through at least one laser unit of the laser chip. The at least two electrodes are configured to be in electrical contact with the at least one laser unit.

[0035] In one aspect of the present invention, the laser chip includes at least one positive-polarity electrode and at least one negative-polarity electrode, and the electrodes are configured to be in electrical contact with at least one laser unit so as to allow current to flow through the at least one laser unit.

[0036] In one aspect of the present invention, at least one electrode of a given polarity is disposed on at least one laser unit.

[0037] In one aspect of the present invention, the laser chip comprises the same number of positive-polarity electrodes as the number of laser units. In other words, each positive electrode is in electrical contact with a separate laser unit. For example, the laser chip comprises one laser unit and one positive-polarity electrode, or the chip comprises two laser units and two positive-polarity electrodes, or the chip comprises three laser units and three positive-polarity electrodes, or the chip comprises N laser units and N positive-polarity electrodes.

[0038] In one aspect of the present invention, the laser chip comprises the same number of negative-polarity electrodes as the number of laser units. In other words, each negative electrode is in electrical contact with a separate laser unit. For example, the laser chip comprises one laser unit and one negative-polarity electrode, or the chip comprises two laser units and two negative-polarity electrodes, or the chip comprises three laser units and three negative-polarity electrodes, or the chip comprises N laser units and N negative-polarity electrodes.

[0039] In one aspect of the present invention, the laser chip comprises a positive-polarity electrode configured to be in electrical contact with all the laser units at once.

[0040] In one aspect of the present invention, the laser chip comprises a negative-polarity electrode configured to be in electrical contact with all the laser units at once.

[0041] In one aspect of the present invention, at least one electrode is disposed on the lower surface of the substrate.

[0042] In one aspect of the present invention, all electrodes of the same polarity are disposed on the same surface of the substrate.

[0043] In one aspect of the present invention, the electrode is configured to be electrically connected to a base plate, particularly to the electrical tracks of the base plate.

[0044] In one aspect according to the present invention, the distance between two adjacent laser units distributed between two sides of the substrate is 10 μm to 150 μm, preferably 20 μm to 150 μm, more preferably 30 μm to 150 μm, more preferably 40 μm to 150 μm, more preferably 50 μm to 150 μm, more preferably 75 μm to 125 μm, and more preferably equal to 100 μm. In other words, across the entire width of the chip, the distance between two adjacent laser units is 75 to 150 μm, preferably 75 μm to 125 μm, and more preferably equal to 100 μm. In this way, the distance between two adjacent laser units is configured such that the electrodes on the same surface are not electrically connected to each other.

[0045] In one aspect of the present invention, the distance between two adjacent laser units distributed between two sides of the substrate is constant. In other words, when the laser chip includes N laser units and N is 2 or more, the distance between the first laser unit and the second laser unit across the entire width of the substrate is the same as the distance between the second laser unit and the third laser unit, and this distance is the same as the distance between the (N - 1)th laser unit and the Nth laser unit.

[0046] In one aspect of the present invention, the distance between at least two adjacent laser units distributed between two sides of the substrate varies. In other words, the distance between the first laser unit and the second laser unit across the entire width of the substrate is different from the distance between the second laser unit and the third laser unit.

[0047] In one aspect of the present invention, the electrode is formed by depositing a conductive material, particularly a metal material, configured to be in electrical contact with at least one laser unit, on the substrate. For example, the conductive metal material is selected from gold, copper, silver, or aluminum.

[0048] In one aspect of the present invention, the substrate comprises at least one semiconductor material of InP (indium phosphide) or GaAs (gallium arsenide) or GaSb (gallium antimonide) or InAs (indium arsenide) or silicon type.

[0049] In one aspect of the present invention, the laser chip comprises at least one electrical insulation layer, and the electrical insulation layer is configured to electrically insulate laser units arranged on the same surface of the substrate from each other. In this way, each laser unit has its own current flowing through it.

[0050] In one aspect of the present invention, the electrical insulation layer is obtained by depositing an electrical insulation material on the substrate. For example, the electrical insulation material is selected from silicone or rubber.

[0051] In one aspect of the present invention, the electrical insulation layer is arranged between the upper surface of the substrate and at least one electrode arranged on the upper surface.

[0052] In one aspect of the present invention, the laser chip comprises at least one wall between two electrodes, and the wall is covered by the electrical insulation layer. The wall helps to flatten the surface of the laser chip, especially when the laser unit is on the upper or lower surface of the substrate.

[0053] In one aspect of the present invention, the laser chip is a quantum cascade laser chip. In other words, at least two laser units are quantum cascade laser units.

[0054] In one aspect of the present invention, the laser unit is configured to emit optical radiation in pulse mode. In particular, this mode reduces the energy required to supply power to the laser unit as compared to continuous operation. Therefore, the efficiency (optical energy / required electrical energy) of the laser unit is improved.

[0055] In one aspect of the present invention, at least one laser unit is configured to emit light radiation having an infrared, preferably mid-infrared wavelength.

[0056] In one aspect of the present invention, at least one laser unit is configured to emit light radiation in a wavelength range of 3 to 15 microns, preferably 4 to 10 microns.

[0057] In one aspect of the present invention, all laser units on the laser chip are configured to emit light radiation of the same wavelength.

[0058] In one aspect of the present invention, at least two laser units of the laser chip are configured to emit light radiation of different wavelengths.

[0059] In one aspect of the present invention, the laser chip comprises N laser units, where N is 2 or more, and at least one of the laser units is configured such that a current flowing through it is low enough to allow heat to be generated without emitting light radiation, and at least one other laser unit is configured such that a current flowing through it is high enough to generate light radiation.

[0060] In one aspect of the present invention, the laser chip comprises at least N laser units, where N is 2 or more, and at least two laser units are configured to emit light radiation of a given wavelength under different atmospheric conditions, particularly at different temperatures.

[0061] In one aspect of the present invention, the laser chip is configured to operate only the laser units that emit light radiation of a given wavelength under ambient atmospheric conditions, particularly ambient temperature.

[0062] The present invention also relates to at least one semiconductor laser chip as described above, and a base plate to which the laser chip is attached, and Relates to a chip-based assembly comprising...

[0063] In other words, the chip / base plate assembly comprises a laser chip as described above, and the chip is disposed on the base plate. That is, the laser chip and the base plate are overlapped.

[0064] In one aspect of the present invention, the lower surface of the laser chip substrate faces the base plate. In other words, the lower surface of the laser chip substrate is disposed on the base plate, and the upper surface of the substrate is on the opposite side of the base plate.

[0065] In one aspect of the present invention, the electrodes disposed on the lower surface of the substrate are disposed on the base plate.

[0066] In one aspect of the present invention, the laser chip is fixed to the base plate, for example, by welding or adhesion.

[0067] In one aspect of the present invention, the base plate comprises at least one base made of a material having heat dissipation characteristics selected from copper and AlN.

[0068] In one aspect of the present invention, the base plate comprises a thermal management element, particularly a Peltier element.

[0069] The base plate particularly has the function of thermal management of the laser chip. The base plate actually enables good heat dissipation.

[0070] In one aspect of the present invention, the base of the base plate is a parallelepiped.

[0071] In one aspect of the present invention, the base of the base plate comprises an upper surface, a lower surface, and two side surfaces, and the upper surface is on the opposite side of the lower surface. The modifiers lower side and upper side are conventions for distinguishing these two surfaces.

[0072] In one aspect of the present invention, the laser unit of the laser chip is closer to the lower surface of the laser chip substrate than to the upper surface of the laser chip substrate, and thus closer to the base plate.

[0073] In one aspect of the present invention, the laser unit of the laser chip is closer to the lower surface of the laser chip substrate, and thus closer to the lower surface of the laser chip substrate than to the upper surface of the base plate.

[0074] In one aspect of the present invention, the base plate comprises at least two electrical tracks of different polarities, and each of the electrical tracks is configured to be in electrical contact with at least one electrode of the same polarity on the laser chip.

[0075] In one aspect of the present invention, the electrical track is configured to be in electrical contact with at least one laser unit.

[0076] In one aspect of the present invention, the at least one laser unit is configured to be in electrical contact with at least two electrodes of the laser chip, and the electrodes are electrically connected to the electrical track. In this way, the laser unit is configured to be in electrical contact with the base plate, and more specifically, with the electrical track of the base plate.

[0077] In one aspect of the present invention, the base plate comprises the same number of electrical tracks of a given polarity as the laser chip has electrodes of the same polarity. In other words, the base plate comprises the same number of positive-polarity electrical tracks as the laser chip has positive-polarity electrodes, and the base plate comprises the same number of negative-polarity electrical tracks as the chip has negative-polarity electrodes.

[0078] In one aspect of the present invention, the base plate comprises a positive-polarity electrical track configured to be in electrical contact with all the positive-polarity electrodes on the laser chip.

[0079] In one aspect of the present invention, the base plate comprises a negative electrical track configured to be in electrical contact with all the negative electrodes on the laser chip.

[0080] In one aspect of the present invention, each of the electrical tracks is disposed on the base of the base plate.

[0081] In one aspect of the present invention, each of the electrical tracks is disposed on the same surface of the base of the base plate, particularly on the upper surface of the base.

[0082] In one aspect of the present invention, the electrical track is formed by depositing a conductive material, particularly a metal deposit, on the base.

[0083] In one aspect of the present invention, the chip-base plate assembly comprises at least one electrical connector configured to electrically connect the electrical leads of the base plate to at least one electrode of the chip. The electrical connector is, for example, a wire or a plate comprising a conductive material, particularly gold, copper, aluminum or silver.

[0084] In one aspect of the present invention, the electrical connector is connected, on the one hand, to at least one electrode of a given polarity on the laser chip by an electrical contact zone, particularly by soldering or bonding, and, on the other hand, to at least one electrical track on the base plate having the same polarity as the electrode. The electrical contact zone comprises, for example, a conductive material such as gold, copper, aluminum or silver.

[0085] In one aspect of the present invention, the electrical contact zone at least partially covers the electrode of the laser chip.

[0086] In one aspect according to the present invention, the electrical contact zone has a diameter of 100 μm or less, preferably 90 μm or less, preferably 80 μm or less, preferably 70 μm or less, preferably 60 μm or less, preferably 60 μm or less, preferably 50 μm or less, preferably 25 μm or less, preferably 10 μm or less.

[0087] In one aspect of the present invention, the electric track is configured to be in electrical contact with at least one electrode via a bonding zone. The bonding zone means a bonding zone where the contact between the electric track and the electrode is physical. In other words, the electrode and the electric track are overlapped with each other. In this case, it is not necessary to use an electrical connector to electrically contact the at least one electrode and the electric track.

[0088] In one aspect of the present invention, the laser chip comprises N laser units, where N is 2 or more, and at most N - 1 of the laser units are electrically connected to the electric track of the base plate. In other words, at least one laser unit is not electrically connected to the electric track of the base plate. In this way, only the most efficient laser units are in electrical contact with the base plate.

[0089] In one aspect of the present invention, the laser chip comprises N laser units, where N is 2 or more, and at least one of the N laser units is configured such that a current low enough to allow heat to be generated without emitting optical radiation flows through it, and at least one other laser unit is configured such that a current high enough to generate optical radiation flows through it.

[0090] In one aspect of the present invention, the chip comprises N laser units, where N is 2 or more, and at least one of the laser units is configured to emit optical radiation having a wavelength different from that of the other laser units.

[0091] In one aspect of the present invention, the chip - base plate assembly comprises at least two chips as described above.

[0092] In one aspect of the present invention, a chip - based plate assembly comprises at least one laser chip having N laser units, where N is 2 or more, and at least one of the laser units is configured such that a current low enough to allow heat to be generated without emitting optical radiation flows through it, and at least one other laser unit is configured such that a current high enough to generate optical radiation flows through it.

[0093] In one aspect of the present invention, a chip - based plate assembly comprises at least one laser chip having at least N laser units, where N is 2 or more, and at least two laser units are configured to emit optical radiation of a given wavelength under different atmospheric conditions, particularly at different temperatures.

[0094] In one aspect of the present invention, a chip - based plate assembly is configured to operate only the laser units that emit optical radiation of a given wavelength in accordance with the ambient atmospheric conditions, particularly the ambient temperature. In this way, the chip - based plate assembly operates the laser units that are most suitable for the atmospheric conditions such as temperature.

[0095] The present invention also relates to a cell forming a resonator comprising a gas inlet duct, a gas outlet duct, and at least one laser inlet opening, at least one chip - based plate assembly as described above having at least two laser units, wherein at least one of the two laser units is configured to emit optical radiation having a wavelength particularly suitable for exciting a gas whose value is to be detected into the cell, whereby the interaction between the optical radiation and the gas to be detected contained in the cell induces the generation of a signal characteristic of the presence of the gas at the resonant frequency of the cell, and at least one chip - based plate assembly, a signal detection device, and relates to a gas sensor comprising the same.

[0096] In one aspect according to the present invention, the gas sensor comprises: a cell forming an optical resonator having a gas inlet duct, a gas outlet duct, and at least one opening called a laser inlet; at least one chip-based plate assembly as described above comprising at least two laser units, wherein at least one of the two laser units is configured to emit light radiation having a wavelength particularly adapted to the excitation of the gas whose value is to be detected into the cell, whereby the interaction between the light radiation and the gas to be detected contained in the cell induces the generation of an optical signal characteristic of the presence of the gas at the resonance frequency of the cell; a signal detection device; and.

[0097] In one aspect of the present invention, the gas sensor comprises a focusing or collimating device, in particular a lens configured to collimate or focus the light radiation from the at least one laser unit.

[0098] In another embodiment according to the present invention, the gas sensor according to the present invention is a photoacoustic gas sensor including the features described in French Patent No. 3084745.

[0099] In this embodiment, the gas sensor comprises: a cell forming an acoustic resonator having a gas inlet duct, a gas outlet duct, and at least one opening called a laser inlet; at least one chip-based plate assembly as described above comprising at least two laser units, wherein at least one of the two laser units is configured to emit light radiation having a wavelength particularly adapted to the excitation of the gas whose value is to be detected into the cell, whereby the interaction between the light radiation and the gas to be detected contained in the cell induces the generation of an acoustic wave at the resonance frequency of the cell; at least one detection microphone disposed in a chimney opening into the cell; comprises.

[0100] In another aspect of the present invention, the chip-based plate assembly is placed directly in front of the laser input section of the cell without an intervening focusing or collimating optical element.

[0101] In one aspect of the present invention, the chip-based plate assembly is placed inside the sensor cell.

[0102] In another aspect of the present invention, the photoacoustic gas sensor comprises a focusing or collimating device, in particular a lens configured to collimate or focus the light radiation from said at least one laser unit.

[0103] In one aspect of the present invention, the sensor comprises a power supply circuit configured to operate the laser source in pulse mode. In particular, this mode makes it possible to reduce the power consumption for the operation of said sensor as compared to operation in continuous mode. Thus, the laser efficiency corresponding to the light energy / electrical energy ratio is improved.

[0104] In one aspect of the present invention, the gas sensor has an overall length of less than 5 cm and an overall width of less than 4 cm.

[0105] In one aspect of the present invention, the cell is of the dual Helmholtz resonator type connected to a detection microphone and comprising two first cavities each having a laser input section and two other cavities connected to the first cavities and comprising a gas inlet duct and a gas outlet duct.

[0106] In one aspect of the present invention, the cylindrical cavity of the cell has a diameter of less than 2 mm.

[0107] In one aspect of the present invention, the walls of the cell have a light reflectivity of more than 50%, preferably more than 75%.

[0108] In one aspect of the present invention, the gas sensor comprises a chip-based plate assembly comprising at least N laser units, where N is 2 or more, and at least two laser units are configured to emit optical radiation of a given wavelength under different atmospheric conditions, in particular at different temperatures.

[0109] In one aspect of the present invention, the sensor is configured to operate only the laser units that emit optical radiation of a given wavelength in accordance with the ambient atmospheric conditions, in particular the ambient temperature. In this way, the sensor operates the laser unit that is most suitable for the atmospheric conditions such as temperature.

[0110] In one aspect according to the present invention, the sensor comprises a chip-based plate assembly comprising at least N laser units, where N is 2 or more, and at least two laser units are configured to emit optical radiation at different wavelengths corresponding to different excitation wavelengths of the same gas or the same molecule of said gas, and the sensor is configured to operate at least two laser units simultaneously so as to reveal the characteristics of the gas under investigation.

[0111] In one aspect of the present invention, the chip-based plate assembly of the gas sensor comprises at least N laser units, where N is 2 or more, and at least one of the laser units is configured such that a sufficiently low current flows to generate heat without emitting optical radiation, and at least one other laser unit is configured such that a sufficiently high current flows to generate optical radiation. In this way, the thermal management of the gas sensor is optimized.

[0112] The present invention also relates to depositing a layer of material to form at least two laser units on a substrate, wherein the laser units are spaced apart by a certain interval in the width dimension of the substrate, and the substrate has a thickness corresponding to the distance between the upper and lower surfaces of the substrate. Cleaving the substrate so as to form two side surfaces of the substrate, wherein the width of the obtained substrate corresponds to the distance between the two obtained side surfaces, and the width is not more than four times the thickness of the substrate; forming a laser chip by ; attaching the obtained chip to a base plate; relates to a method for producing a chip-base plate assembly comprising .

[0113] In one aspect of the present invention, the fixing step is performed either by welding or adhesion.

[0114] In one aspect of the present invention, the method comprises cutting a wafer to obtain a desired number of laser chips, the wafer comprising a substrate and a plurality of laser units.

[0115] Further features, details and advantages of the present invention will become apparent from the description given hereinafter by way of example in connection with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0116]

Figure 1

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Figure 8

[0117] FIG. 1 shows a photoacoustic gas sensor 1 according to the present invention. The photoacoustic sensor 1 according to the present invention can have the characteristics of the photoacoustic sensors described in French Patent No. 3084745.

[0118] The photoacoustic gas sensor 1 according to the present invention includes a cell 20 having a gas inlet duct 60 and a gas outlet duct 70, and a chip-based plate assembly 100 having a laser chip disposed on a base plate, wherein the laser chip includes at least two laser units, and at least one of them is configured to emit light radiation having a wavelength in the mid-infrared range. The chip-based plate assembly includes a chimney 30 that opens into the cell and includes a detection microphone 50, and an opening called a laser inlet 40.

[0119] In the embodiment shown in FIG. 1, the chip-based plate assembly 10 is attached to the laser input portion 40, whereby the laser radiation emitted by at least one laser unit of the chip-based plate assembly 100 is directly emitted into the cell 20 without the intervention of an optical focusing element. In the embodiment shown in FIG. 1, the laser radiation is generated by at least one quantum cascade laser unit (QCL) included in the chip-based plate assembly 10, and the laser unit emits in pulse mode at 4 to 10 microns. The QCL laser unit takes the form of a rod typically having dimensions of 3 mm × 10 μm × 20 μm. The divergence of the laser beam from the laser rod is typically 60°. The chip-based plate assembly 10 may be operated, for example, in pulse mode at a frequency sufficiently higher than the resonance frequency of the cell to avoid possible interference.

[0120] The photoacoustic sensor 1 also includes an electronic detection circuit 80 connected to a detection microphone 50. In the embodiment shown in FIG. 1, the gas is introduced via an inlet duct 60 and discharged via an outlet duct 70. Both ducts are directly connected to the cell 20. During the interaction between the laser emitted by at least one laser unit of the 10 chip - based plate assembly and the gas in the cell 20, the gas is excited. The excited vibrational levels are de - excited by non - radiative transitions, resulting in molecular collisions and heating of the gas. In this way, acoustic waves and thermal waves are generated, and the acoustic waves are detected by the detection microphone 50 disposed in a chimney 30 connecting the microphone 50 to the cell 20. The microphone 50 is connected to the detection circuit 80, and the detection circuit 80 determines the amplitude of the acoustic wave and thus determines the concentration of the gas species under investigation. Since the chip - based plate assembly 10 is disposed directly in front of the input surface, this design requires only basic alignment. In addition, the absence of focusing optical elements in the sensor architecture makes the sensor much more resistant to shock and / or vibration, less susceptible to misalignment, and less expensive. This architecture extends the operating time and application range of the sensor.

[0121] The chip - based plate assembly 10 enables light radiation to be emitted into the cell 20 at a wavelength particularly adapted to the generation of the photoacoustic effect in the gas under investigation.

[0122] The inner wall of the gas cell 20 has infrared reflective optics in order to maximize the laser beam interacting with the atoms or molecules of the gas under investigation. For example, the cell has a light reflectivity of more than 50%, preferably more than 75%.

[0123] The chip - based plate assembly of the photoacoustic sensor 1 according to the present invention may be selected from the chip - based plate assemblies described in FIGS. 2 - 8 of this specification. The features of these chip - based plate assemblies are described in more detail in FIGS. 2 - 8.

[0124] Figure 2 shows the chip - based plate assembly 100 in the first embodiment.

[0125] In this embodiment, the chip - based plate assembly 100 includes a laser chip 101 and a base plate 111 on which the laser chip 101 is disposed.

[0126] The laser chip 101 is a substrate, particularly a cleaved substrate 105, which has two side surfaces 107, a bottom surface 109 and a top surface 108, and the substrate 105; three semiconductor laser units 102 disposed on the top surface 108 of the substrate 105, and the three laser units 102 are distributed between the two side surfaces 107 of the substrate 105 with a gap E between two adjacent laser units 102; and it comprises.

[0127] In this example, the width l of the substrate 105 is equal to the width of the laser chip.

[0128] In other words, the three laser units 2 are distributed over the width l of the substrate 105. In this way, the entire width l of the substrate, and thus of the laser chip, is utilized. This improves the production efficiency of the laser chip 101.

[0129] The substrate 105 of the laser chip 101 has a width l less than four times the thickness e of the substrate. In this example, the width l of the substrate is 1.5 to 3 times larger than the thickness e, preferably 2.5 times larger than the thickness e of the substrate 105.

[0130] In this way, the surface area of the material used to produce the laser chip 101 is reduced, and the production cost of the laser chip 101 is reduced. Furthermore, the ratio of the width l to the thickness e of the substrate of the laser chip 105 gives the laser chip the strength required to avoid breakage during the cleavage stage. The width l of the substrate 105 is, for example, 250 μm to 300 μm, and the thickness e of the laser chip 101 is, for example, 120 μm to 150 μm.

[0131] In this embodiment, the laser chip 101 has an "up" configuration, that is, the laser unit 102 is closer to the upper surface 108 of the substrate 105 than to the lower surface 109 of the substrate 105. More precisely, the laser unit 102 is arranged on the upper surface 108 of the substrate 105 of the laser chip 101.

[0132] The laser chip 101 includes three positive-polarity electrodes 103, and each of these three electrodes 103 is configured to be in electrical contact with the laser unit 102. The three positive-polarity electrodes 103 are respectively superimposed on the laser unit 102 and arranged on the upper surface 108 of the substrate 105 of the laser chip 101. The laser chip 101 includes a negative-polarity electrode 103 configured to be in electrical contact with all three laser units 102 simultaneously. Here, the negative-polarity electrode 103 is arranged on the lower surface 109 of the substrate 105 of the laser chip 101. The electrodes 103 are formed here by the deposition of a conductive material, especially a metal material such as gold.

[0133] The laser chip 101 includes an electrical insulation layer 104 configured to electrically insulate the laser units 102 arranged on the same surface of the substrate 105, in this case, the laser units 102 arranged on the upper surface 108 of the substrate 105 from each other. The electrical insulation layer 104 is formed by depositing an electrical insulation material selected from silicone or rubber on the upper surface 108 of the substrate 105. The electrical insulation layer 104 is arranged between the upper surface 108 of the substrate 105 and the electrodes 103 arranged on the upper surface 108 of the substrate.

[0134] The laser chip 101 includes a wall 106, and the wall 106 is covered by the electrical insulation layer 104. These walls 106 are arranged between two adjacent laser units 102 so as to flatten the upper surface of the laser chip.

[0135] The distance E between two adjacent laser units 102 is large enough so that the electrodes 103 on the same surface do not electrically contact each other. The distance E between two adjacent laser units 102 is constant, that is, the distance E between the first and second laser units 102 is the same as the distance E between the second and third laser units 102. This distance E is, for example, 100 μm. In an embodiment not shown here, the distance E varies between two adjacent electrodes 103.

[0136] To facilitate handling, the laser chip 101 is attached to a base plate 111. The base plate 111 is a parallelepiped and has dimensions of 5 mm × 6 mm × 1.2 mm. The base plate 111 includes a thermal management element, particularly a Peltier element. The base plate 111 includes a base 115 made of a material having heat dissipation characteristics, particularly AlN. Therefore, the base plate 111 also has the function of ensuring good thermal management of the laser chip 101.

[0137] The base plate 111 includes two electrical tracks 112 of different polarities, and the two electrical tracks are arranged on the upper surface 117 of the base 115. One of the electrical tracks 112 is of negative polarity, and the other electrical track 112 is of positive polarity. The positive-polarity 112 is in electrical contact with one of the positive-polarity 103 electrodes of the laser chip 101, and the negative-polarity 112 is in electrical contact with the negative-polarity 103 electrode of the laser chip 101. Thus, an electric field is formed between the two electrodes 103, and current flows through the laser unit 102. The positive-polarity electrical track 112 is here in electrical contact with the positive-polarity electrode 103 via an electrical connector 113 which may be a gold wire connecting the electrical track 112 and the electrode 103, and the electrical connector 113 is connected to the electrode via an electrical contact zone 114, here a gold-based solder. The negative-polarity electrical track 112 is in electrical contact with the negative-polarity electrode 103 of the laser chip 101 via a bonding zone 116 between the electrical track 112 and the electrode 103.

[0138] The advantage of such a design is that only the most efficient 102 laser units, i.e., the most efficient laser units, are in electrical contact with the base plate 111.

[0139] FIG. 3 shows a second example of a chip-base plate assembly 200 according to the present invention. In this embodiment, the laser chip 201 includes the same features as the embodiment shown in FIG. 2, except that two laser units 202 are in electrical contact with different positive-polarity electrodes 203 and a common negative-polarity electrode 203, respectively.

[0140] Therefore, the substrate 205 of the laser chip 201 has a width l of less than four times the thickness of the substrate. In this example, the width l of the substrate is 1.5 to 3 times greater than the thickness e, preferably 2.5 times greater than the thickness e of the substrate 205.

[0141] The laser chip here includes three laser units 202.

[0142] The base plate 211 includes three electrical tracks 212 of different polarities, and the three electrical tracks are arranged on the upper surface 217 of the base 215 of the base plate 211. One of the electrical tracks 212 is of negative polarity, and the other two electrical tracks 212 are of positive polarity. The two electrical tracks 212 of positive polarity are in electrical contact with separate positive electrodes 203 on the laser chip 201, and each of the electrodes 203 is connected to the laser unit 202. The electrical track 212 of negative polarity is in electrical contact with the negative electrode 203 of the laser chip 201. Therefore, current flows through each laser unit 202 in contact with the positive electrode 203 and the negative electrode 203.

[0143] The electrical track 212 of positive polarity is here in electrical contact with the positive electrode 203 via an electrical connector 213 which may be a gold wire connecting the electrical track 212 to the electrode 203. The electrical connector 213 is connected to the electrode 203 via a gold-based solder 214. The electrical track 212 of negative polarity is in electrical contact with the negative electrode 203 via a bonding zone 216 between the electrical track 212 and the electrode 203.

[0144] The advantage of this type of design is that only the two most performant laser units 202 are in electrical contact with the base plate 211, and thus current flows. In other words, the laser units 202 with the best optical performance are selected.

[0145] In this example, the two laser units 202 in electrical contact with the base plate 211 can be configured to emit light radiation of the same wavelength or different wavelengths.

[0146] Another advantage of this design is that one of the laser units 202 in electrical contact with the base plate 211 may be configured to receive a current that is weak enough not to emit light radiation but strong enough to emit heat, while the other laser units 202 in electrical contact with the base plate 211 are configured to receive a current strong enough to emit light radiation. In this way, the heat-radiating laser unit is involved in the thermal management of the 200 chip-base plate assembly, thereby reducing the costs associated with the thermal management of such an assembly without causing light emission interference.

[0147] Advantageously, the laser unit 202 can be configured to emit light radiation of a given wavelength under different atmospheric conditions, particularly at different temperatures. In this way, only the laser unit 202 that emits the desired wavelength under ambient conditions is turned on, so as not to supply energy to the second laser unit 202 unnecessarily.

[0148] FIG. 4 shows a third example of a chip-base plate assembly 300 according to the present invention. In this embodiment, the laser chip 301 has the same features as the embodiment shown in FIG. 2, except that all the laser units 302 are in electrical contact with electrodes 303 of different polarities and a common electrode 303 of opposite polarity.

[0149] Accordingly, the substrate 305 of the laser chip 301 has a width l that is less than four times the thickness of the substrate. In this example, the width l of the substrate is 1.5 to 3 times, preferably 2.5 times, greater than the thickness e of the substrate 305.

[0150] Here, the laser chip includes three 302 laser units.

[0151] The base plate 311 includes four electrical tracks 312 of different polarities, and the four electrical tracks 312 are arranged on the upper surface 317 of the base 315 of the base plate 311. One of the 312 electrical tracks is of negative polarity, and the other three 312 electrical tracks are of positive polarity. The three electrical tracks 312 are in electrical contact with separate positive-polarity electrodes 303 on the laser chip 301, and each of the positive-polarity electrodes 303 is connected to a separate laser unit 302. The negative-polarity electrical track 312 is in electrical contact with the negative-polarity electrode 303 on the laser chip 301. Therefore, current flows through the laser units 302 in contact with the positive and negative electrodes 303.

[0152] The positive-polarity electrical track 312 is here in electrical contact with the positive-polarity electrode 303 via an electrical connector 313, and the electrical connector may be a gold wire connecting the electrical track 312 to the electrode 303. The electrical connector 313 is connected to the electrode 303 via a gold-based solder 314. The negative-polarity electrical track 312 is in electrical contact with the negative-polarity electrode 303 via a bonding zone 316 between the electrical track 312 and the electrode 303.

[0153] In this example, the two laser units 302 in electrical contact with the base plate 311 can be configured to emit light radiation of the same wavelength or different wavelengths.

[0154] One advantage of this design is that one of the laser units 302 in electrical contact with the base plate 311 may be configured to receive a current that is weak enough not to emit light radiation but strong enough to dissipate heat, while the other laser units 302 in electrical contact with the base plate 311 are configured to receive a current strong enough to emit light radiation. In this way, the heat-radiating laser unit 302 is involved in the thermal management of the chip-base plate assembly 300, thereby reducing the cost associated with the thermal management of such an assembly without causing emission interference.

[0155] Advantageously, the laser unit 302 can be configured to emit light radiation of a given wavelength under different atmospheric conditions, in particular at different temperatures. In this way, only the laser unit 302 that emits the desired wavelength under the ambient conditions is turned on, and it is possible to avoid unnecessarily supplying energy to the second laser unit 302.

[0156] FIG. 5 shows a chip-based plate assembly 400 in a fourth embodiment.

[0157] In this embodiment, the chip-based plate assembly 400 includes all the features of the embodiment shown in FIG. 2, except that the chip-based plate assembly is in the "down" position, that is, the laser unit 402 is arranged closer to the lower surface 409 than to the upper surface 408 of the substrate 405.

[0158] Accordingly, the substrate 405 of the laser chip 401 has a width l of less than four times the thickness of the substrate. In this example, the width l of the substrate is 1.5 to 3 times larger than the thickness e, preferably 2.5 times larger than the thickness e of the substrate 405.

[0159] The laser chip comprises three laser units 402.

[0160] In this example, the laser unit 402 is arranged on the lower surface 409 of the substrate 405.

[0161] In this example, only the positive electrode 403 of the laser chip is electrically connected to the positive electrical track 412 of the base plate 411. Accordingly, current flows only to the positive electrode 403 on the one hand and to the laser unit 402 electrically connected to the negative electrode 403 on the other hand.

[0162] The negative electrical track 412 is here in electrical contact with the negative electrode 403 of the laser chip 401 via an electrical connector 413, which may here be a gold wire connecting the electrical track 412 and the electrode 403. The electrical connector 413 is electrically connected to the electrode via a gold-based solder 414. The positive electrical track 412 is in electrical contact with the positive electrode via a bonding zone 416 between the electrical track 412 and the electrode 403.

[0163] Figure 6 shows a fifth example of a chip-based plate assembly 500 according to the present invention.

[0164] Accordingly, the substrate 505 of the laser chip 501 has a width l of less than four times the thickness of the substrate. In this example, the width l of the substrate is 1.5 to 3 times greater than the thickness e, preferably 2.5 times greater than the thickness e of the substrate 505.

[0165] The laser chip comprises three laser units 502.

[0166] In this embodiment, the chip-based plate assembly 500 includes all the features of the embodiment shown in FIG. 3, except that the chip-based plate assembly is in the "downward" position, i.e., the laser unit 502 is disposed closer to the lower surface 509 than to the upper surface 508 of the substrate 505.

[0167] In this example, the laser unit 502 is disposed on the lower surface 509 of the substrate 505.

[0168] In this example, the two positive electrodes 503 of the laser chip 501 are each electrically connected to the positive electrical track 512 of the base plate 511. Accordingly, current flows only through the laser units 502 that are electrically connected on the one hand to the positive electrode 503 of the laser chip 501 and on the other hand to the negative electrode 503 of the laser chip 501.

[0169] The negative electrical track 512 is, here, in electrical contact with the negative electrode 503 of the laser chip 501 via an electrical connector 513 which may here be a gold wire connecting the electrical track 512 and the electrode 503. The electrical connector 513 is electrically connected to the electrode via a gold-based solder 514. The positive electrical track 512 is in electrical contact with the positive electrode via a bonding zone 516 between the electrical track 512 and the electrode 503.

[0170] FIG. 7 shows a sixth example of a chip-based plate assembly 600 according to the present invention.

[0171] Thus, the substrate 605 of the laser chip 601 has a width l of less than four times the thickness of the substrate. In this example, the width l of the substrate is 1.5 to 3 times greater than the thickness e, preferably 2.5 times greater than the thickness e of the substrate 605.

[0172] The laser chip comprises three laser units 602.

[0173] In this embodiment, the chip-based plate assembly 600 includes all the features of the embodiment shown in FIG. 4, except that the chip-based plate assembly is in the "downward" position, i.e., the laser unit 602 is disposed closer to the lower surface 609 than to the upper surface 608 of the substrate 605.

[0174] In this example, the three positive electrodes 603 are each electrically connected to a positive electrical track 612 on the base plate 611. Thus, current flows through all the laser units 602 that are electrically connected to the positive electrode 603 on the one hand and to the negative electrode 603 on the other hand.

[0175] The negative electrical track 612 is electrically in contact here with the negative electrode 603 via an electrical connector 613 which may here be a gold wire connecting the electrical track 612 and the electrode 603, the electrical connector 613 being electrically connected to the electrode via a gold-based solder 614. The positive electrical track 612 is electrically in contact with the positive electrode via a bonding zone 616 between the electrical track 612 and the electrode 603.

[0176] Figure 8 shows a 700 chip - baseplate assembly in a seventh embodiment.

[0177] In this embodiment, the chip - baseplate assembly 700 includes all the features of the embodiment shown in FIG. 2, except that the laser unit 702 is embedded in the substrate 705 of the chip 701.

[0178] Accordingly, the substrate 705 of the laser chip 701 has a width l of less than four times the thickness of the substrate. In this example, the width l of the substrate is 1.5 to 3 times, preferably 2.5 times, greater than the thickness e of the substrate 705.

[0179] The laser chip comprises three laser units 702.

[0180] In this embodiment, the laser unit 702 is closer to the upper surface 708 of the substrate 705 than to the lower surface 709 of the substrate 705.

[0181] In this embodiment, only one positive electrode 703 is electrically connected to the electrical track 712 on the baseplate. Accordingly, current flows through only one laser unit 702.

[0182] In another embodiment, as shown in FIGS. 3 and 4, a plurality of positive electrodes 703 may be electrically connected to the positive electrical track 712.

[0183] In an embodiment not shown here, the laser unit 702 may be embedded in the substrate 705 so as to be closer to the lower surface 709 of the substrate 705 than to the upper surface 708 of the substrate.

[0184] In this embodiment, the substrate includes layers of semi-insulating material on both sides of these laser units so as to electrically insulate the 702 laser units from each other.

[0185] Other features of the embodiments shown in FIGS. 2 to 7 are applied here.

Claims

1. Two sides (107, 207, 307, 407, 507, 607, 707) and Bottom surface (109, 209, 309, 409, 509, 609, 709) and Top surface (108, 208, 308, 408, 508, 608, 708) and A substrate (105, 205, 305, 405, 505, 605, 705) comprising, At least two semiconductor lasers (202, 302, 402, 502, 602, 702), wherein these two lasers (102, 202, 302, 402, 502, 602, 702) are dispersed between the two sides (102, 202, 302, 402, 502, 602, 702) with a gap (E) between two adjacent lasers (102, 202, 302, 402, 502, 602, 702), and at least two semiconductor lasers (202, 302, 402, 502, 602, 702), Equipped with, The substrate (105, 205, 305, 405, 505, 605, 705) has a width (l), which is the distance between the two sides (107, 207, 307, 407, 507, 607, 707) of the substrate (105, 205, 305, 405, 505, 605, 705), and a thickness (e), which is the distance measured between the lower surface (109, 209, 309, 409, 509, 609, 709) and the upper surface (108, 208, 308, 408, 508, 608, 708, 808) of the substrate (105, 205, 305, 405, 505, 605, 705) perpendicular to the width (l), wherein the width (l) is 4 times or less the thickness (e). Semiconductor laser chips (101, 201, 301, 401, 501, 601, 701).

2. The chip according to claim 1, characterized in that the substrate (105, 205, 305, 405, 505, 605, 705) has a width (l) that is 1.5 to 3 times greater than the thickness (e).

3. The chip according to claim 1, comprising at least three laser units (102, 202, 302, 402, 502, 602, 702), wherein these three laser units (102, 202, 302, 402, 502, 602, 702) are dispersed between the two sides (107, 207, 307, 407, 507, 607, 707) of the substrate (105, 205, 305, 405, 505, 605, 705) with a gap (E) between two adjacent lasers (102, 202, 302, 402, 502, 602, 702).

4. The chip according to any one of claims 1 to 3, characterized in that the laser unit (102, 202, 302) is closer to the upper surface (108, 208, 308) of the substrate (105, 205, 305) than to the lower surface (109, 209, 309) of the substrate (105, 205, 305).

5. The chip according to any one of claims 1 to 3, characterized in that at least one laser unit (102, 202, 302, 402, 502, 602, 702) of the laser chip (101, 201, 301, 401, 501, 601, 701) comprises at least two electrodes (103, 203, 303, 403, 503, 603, 703) of different polarities configured to allow the passage of current.

6. The chip according to any one of claims 1 to 3, characterized by comprising at least one insulating layer (104, 204, 304, 404, 504, 604, 704) configured to electrically insulate laser units (102, 202, 302, 402, 502, 602, 702) arranged on the same substrate surface (105, 205, 305, 405, 505, 605, 705) from one another.

7. The chip according to any one of claims 1 to 3, characterized in that the substrate (105, 205, 305, 405, 505, 605, 705) comprises at least one semiconductor material selected from InP, GaAs, GaSb, InAs, or silicon type.

8. The chip according to any one of claims 1 to 3, characterized in that the laser chip (101, 201, 301, 401, 501, 601, 701) is a quantum cascade laser chip comprising a quantum cascade laser unit (102, 202, 302, 402, 502, 602, 702).

9. The chip according to any one of claims 1 to 3, characterized in that at least one laser unit (102, 202, 302, 402, 502, 602, 702) is a quantum cascade laser unit that emits in pulse modes of 4 to 10 microns.

10. At least one laser tip (101, 201, 301, 401, 501, 601, 701) according to any one of claims 1 to 3, The base plates (111, 211, 311, 411, 511, 611, 711) to which the aforementioned chips (101, 201, 301, 401, 501, 601, 701) are attached, Assembly including (100, 200, 300, 400, 500, 600, 700).

11. The assembly according to claim 10, characterized in that the base plate (111, 211, 311, 411, 511, 611, 711) comprises at least two electrical tracks (112, 212, 312, 412, 512, 612, 712) of different polarities, and each of the electrical tracks (112, 212, 312, 412, 512, 612, 712) is configured to electrically contact at least one electrode (103, 203, 303, 403, 503, 603, 703) of the same polarity.

12. The assembly according to claim 10, characterized in that the chip (101, 201, 401, 501, 701) comprises N laser units (102, 202, 402, 502, 702), where N is 2 or more, and at most N-1 of the laser units (102, 202, 402, 502, 702) are electrically connected to the electric tracks (112, 212, 412, 512, 712) of the base plate (111, 211, 411, 511, 711).

13. The assembly according to claim 10, wherein the chip-baseplate assembly (100, 200, 300, 400, 500, 600, 700) comprises at least one laser chip (101, 201, 301, 401, 501, 601, 701) having at least N laser units (102, 202, 302, 402, 502, 602, 702), where N is 2 or more, and at least two laser units are configured to emit light radiation of a given wavelength under different atmospheric conditions, particularly at different temperatures.

14. A cell (20) forming a resonator, comprising a gas inlet duct (60), a gas outlet duct (70), and at least one so-called laser inlet opening (40), At least one chip-baseplate assembly (100, 200, 300, 400, 500, 600, 700) according to claim 10, comprising at least two laser units, wherein at least one of the two laser units is configured to emit light radiation into the cell (20) having a wavelength whose value is particularly suited to the excitation of the gas to be detected, thereby causing an interaction between the light radiation and the gas to be detected contained in the cell to induce the generation of a signal characteristic of the presence of the gas at the resonant frequency of the cell, Signal detection device and A gas sensor (1) equipped with the following.

15. A method for depositing layers of material on a substrate to form at least two laser units, wherein the laser units are spaced apart by a certain distance in the width dimension of the substrate, and the substrate has a thickness corresponding to the distance between the upper and lower surfaces of the substrate. Cleaving the substrate so as to form two sides of the substrate, wherein the width of the obtained substrate corresponds to the distance between the two obtained sides, and the width is four times or less the thickness of the substrate, The steps of forming a laser tip and The steps include attaching the obtained chip to a base plate, A method for producing the chip-baseplate assemblies (100, 200, 300, 400, 500, 600, 700) according to claim 10, comprising:

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