External resonant laser module and method of manufacturing external resonant laser module

1 . An external resonant laser module comprising:

a quantum cascade laser element;

a movable diffraction grating constituting an external resonator for the quantum cascade laser element;

a first lens holder disposed on a side opposite to a side where the movable diffraction grating is disposed with respect to the quantum cascade laser element and configured to hold a first lens for passing a first outgoing light from the quantum cascade laser element;

a second lens holder disposed between the quantum cascade laser element and the movable diffraction grating and configured to hold a second lens for passing a second outgoing light from the quantum cascade laser element and a light returned from the movable diffraction grating to the quantum cascade laser element;

a package configured to accommodate the quantum cascade laser element, the movable diffraction grating, the first lens holder, and the second lens holder;

an electrode terminal disposed along one of an inner surface of a pair of side walls of the package; and

a wire configured to electrically connect the electrode terminal and the quantum cascade laser element,

wherein an end portion of the wire is disposed on a side where the quantum cascade laser element is disposed, the end portion of the wire is disposed at a position between the first lens holder and the second lens holder when viewed from a direction orthogonal to a facing direction in which the first lens holder and the second lens holder face each other,

wherein the package includes a bottom wall,

wherein a height position of the electrode terminal with respect to the bottom wall is higher than a height position of the quantum cascade laser element with respect to the bottom wall, and a top surface of the first lens holder or a top surface of the second lens holder is located at a position higher than the electrode terminal,

wherein the wire is connected to the electrode terminal at a position between the first lens holder and the second lens holder when viewed from the direction orthogonal to the facing direction,

wherein the electrode terminal serves as a starting point of a power supply path within the package, and a driving voltage is applied to the quantum cascade laser element from the electrode terminal through the wire to cause laser oscillation, and

wherein the wire is formed in a space within the package and has a loop height.

2 . The external resonant laser module according to claim 1 ,

wherein the pair of side walls are erected on the bottom wall and formed in an annular shape so as to surround a region in which the quantum cascade laser element is accommodated when viewed from a direction perpendicular to the bottom wall, and

wherein the package further includes a top wall closing an opening of the pair of side walls on a side opposite to a side where the bottom wall is disposed.

3 . The external resonant laser module according to claim 1 ,

further comprising an electrode pad through which the electrode terminal is electrically connected with the quantum cascade laser element,

wherein the wire includes:

a first wire that connects the electrode terminal and the electrode pad; and

a second wire that connects the electrode pad and the quantum cascade laser element.

4 . The external resonant laser module according to claim 3 ,

wherein the electrode pad is provided at a position between the first lens holder and the second lens holder when viewed from the direction orthogonal to the facing direction.

5 . The external resonant laser module according to claim 4 ,

wherein the pair of side walls are erected on the bottom wall and formed in an annular shape so as to surround a region in which the quantum cascade laser element is accommodated when viewed from a direction perpendicular to the bottom wall,

wherein the package further includes a top wall closing an opening of the pair of side walls on a side opposite to a side where the bottom wall is disposed, and

wherein a height position of the electrode pad with respect to the bottom wall is lower than the height position of the electrode terminal with respect to the bottom wall and higher than the height position of the quantum cascade laser element with respect to the bottom wall.

6 . A method of manufacturing an external resonant laser module,

wherein the external resonant laser module comprises:

a quantum cascade laser element;

a movable diffraction grating constituting an external resonator for the quantum cascade laser element;

a first lens holder disposed on a side opposite to a side where the movable diffraction grating is disposed with respect to the quantum cascade laser element and configured to hold a first lens for passing a first outgoing light from the quantum cascade laser element;

a second lens holder disposed between the quantum cascade laser element and the movable diffraction grating and configured to hold a second lens for passing a second outgoing light from the quantum cascade laser element and a light returned from the movable diffraction grating to the quantum cascade laser element;

a package configured to accommodate the quantum cascade laser element, the movable diffraction grating, the first lens holder, and the second lens holder; and

a plurality of electrode terminals disposed along an inner wall surface of the package and disposed along a facing direction in which the first lens holder and the second lens holder face each other,

wherein the method comprising:

a first step of disposing the quantum cascade laser element and the movable diffraction grating in the package;

a second step of forming a wire electrically connecting the quantum cascade laser element disposed in the package and a first electrode terminal of the plurality of electrode terminals by wire bonding; and

a third step of disposing the first lens holder in which the first lens is held and the second lens holder in which the second lens is held in the package after the second step,

wherein, in the second step, an end portion of the wire is disposed on a side where the quantum cascade laser element is disposed, the end portion of the wire is disposed at a position between a position at which the first lens holder is to be disposed and a position at which the second lens holder is to be disposed when viewed from a direction orthogonal to a facing direction in which the first lens holder and the second lens holder face each other,

wherein the quantum cascade laser, the movable diffraction grating, the first lens holder, and the second lens holder are disposed in a single space in the package,

wherein the wire is connected to the first electrode terminal at a position between the first lens holder and the second lens holder when viewed from the direction orthogonal to the facing direction,

wherein the first electrode terminal serves as a starting point of a power supply path within the package,

wherein, in the third step, the first lens holder and the second lens holder are fixed in the package by aligning the first lens and the second lens in a state in which a driving voltage is applied to the quantum cascade laser element from the first electrode terminal through the wire to cause laser oscillation, and

wherein the wire is formed in a space within the package and has a loop height.

7 . The external resonant laser module according to claim 3 ,

wherein the pair of side walls are erected on the bottom wall and formed in an annular shape so as to surround a region in which the quantum cascade laser element is accommodated when viewed from a direction perpendicular to the bottom wall,

wherein the package further includes a top wall closing an opening of the pair of side walls on a side opposite to a side where the bottom wall is disposed,

wherein a height position of the electrode pad with respect to the bottom wall is lower than the height position of the electrode terminal with respect to the bottom wall and higher than the height position of the quantum cascade laser element with respect to the bottom wall, and

wherein the electrode terminal, the electrode pad, and the quantum cascade laser element do not overlap in a direction perpendicular to the bottom wall.