CN103814488B - A kind of outside cavity gas laser - Google Patents
A kind of outside cavity gas laser Download PDFInfo
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- CN103814488B CN103814488B CN201280017638.5A CN201280017638A CN103814488B CN 103814488 B CN103814488 B CN 103814488B CN 201280017638 A CN201280017638 A CN 201280017638A CN 103814488 B CN103814488 B CN 103814488B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
- H01S5/14—External cavity lasers
- H01S5/141—External cavity lasers using a wavelength selective device, e.g. a grating or etalon
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Abstract
A kind of outside cavity gas laser, including: chip gain (11), collimating mirror (14), tunable wave length select assembly (15), condenser lens (16) and reflecting mirror (17).Collimating mirror (14) and the optical axis coincidence of condenser lens (16), tunable wave length selects assembly (15) to be positioned between collimating mirror (14) and condenser lens (16), and tunable wave length selects assembly (15) and chip gain (11) to lay respectively at the both sides of collimating mirror (14), the face, one chamber of chip gain (11) is positioned on the focal plane of collimating lens (14), reflecting mirror (17) is positioned on the focal plane of condenser lens (16), and it is perpendicular to the optical axis of condenser lens (16), another face, chamber of reflecting mirror (17) and chip gain (11) defines the resonator cavity of the outside cavity gas laser of the embodiment of the present invention.This outside cavity gas laser has low-loss, low threshold current, good service behaviour, excellent stability and reliability.
Description
Technical Field
The invention relates to the field of optical communication, in particular to an external cavity laser.
Background
With the development of optical communication systems, fixed Wavelength lasers used in early DWDM (Dense Wavelength division multiplexing) systems are gradually replaced by Wavelength tunable lasers. Therefore, wavelength tunable lasers have become a hot spot for recent research.
The prior art provides a wavelength tunable laser, which has a structure as shown in fig. 1, and includes a gain chip 1, a collimating mirror 4, a fixed wavelength selection element 5, a focusing mirror 6, and an Etalon formed by two parallel mirrors 7 and 8. The multi-longitudinal-mode light beam generated by the gain chip 1 is emitted from the cavity surface 3 of the gain chip, then the large-spot parallel light beam obtained by beam expansion and collimation through the collimating lens 4 is filtered by the fixed wavelength selection element 5, the filtered emergent light beam is focused by the focusing lens 6 and enters an Etalon formed by the reflecting mirror 7 and the reflecting mirror 8, and the Etalon reflects the incident light beam back to the active area of the gain chip 4 to form an external cavity resonance light path. The laser realizes the tuning of the wavelength by means of the detuning reflection caused by the fact that the Etalon deviates from the direction orthogonal to the optical axis, namely, the laser outputs laser with different wavelengths (the formed laser is emitted from the cavity surface 2 of the gain chip) by changing the size of an included angle alpha between the Etalon and the direction orthogonal to the optical axis. In fig. 1, a horizontal broken line indicates an optical axis.
However, the wavelength tuning in the prior art is achieved by means of the "detuned" reflection generated when Etalon deviates from the direction orthogonal to the optical axis, which inevitably results in high reflection loss, and the larger the angle between Etalon and the direction orthogonal to the optical axis, the larger the reflection loss, and therefore, the wavelength tunable laser in the prior art has high loss. In addition, because the Etalon does not form any angle with the orthogonal direction of the optical axis to generate the "detuning" reflection effect, the angle with the orthogonal direction of the optical axis needs to be carefully adjusted to enable the laser to output laser light with a specific wavelength, which causes difficulty in wavelength tuning to be increased and time for tuning to output the specific wavelength to be long.
Disclosure of Invention
In view of the defects of the laser in the prior art, the technical scheme of the invention provides the external cavity laser with low loss and high wavelength tuning speed.
An aspect of the present invention provides an external cavity laser including: the device comprises a gain chip, a collimating mirror, a wavelength tunable selection component, a focusing lens and a reflecting mirror;
the gain chip and the wavelength tunable selection component are respectively positioned at two sides of the collimating mirror, and one cavity surface of the gain chip is positioned on a focal plane of the collimating mirror;
the gain chip is used for generating multi-longitudinal-mode light beams, wherein the multi-longitudinal-mode light beams are emitted from the cavity surface;
the collimating lens is used for expanding and collimating the multi-longitudinal-mode light beam emitted from the cavity surface of the gain chip to obtain a parallel light beam;
the wavelength tunable selection component is provided with an adjustable transmission spectrum and is used for filtering the parallel light beams; wherein the different transmission spectra correspond to the external cavity laser outputting laser light of different wavelengths;
the focusing lens is used for converging the filtered parallel light beams to the reflecting mirror;
the reflector is positioned on the focal plane of the focusing lens, is vertical to the optical axis of the focusing lens, and is used for reflecting the light beams incident to the reflecting surface of the reflector to the focusing lens.
In the external cavity laser provided by the technical scheme of the invention, the reflector is vertical to the optical axis of the focusing lens, and the mirror surface of the reflector is positioned on the focal plane of the focusing lens, so that the light incident on the reflecting surface of the reflector can be basically and completely reflected to the focusing lens, and the loss of the external cavity laser is very low. In addition, when the external cavity laser provided by the technical scheme of the invention realizes wavelength tuning, the transmission spectrum of the wavelength tunable selection component is changed by adjusting the wavelength tunable selection component, and the transmission spectrum of the wavelength tunable selection component is very simple and fast to adjust.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a wavelength tunable laser in the prior art;
FIG. 2 is a schematic structural diagram of an external cavity laser according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of another structure of an external cavity laser according to an embodiment of the present invention;
FIG. 4A is a schematic diagram of the longitudinal mode spectrum and the transmission spectrum of Etalon151 in the first example;
FIG. 4B is a schematic diagram of a transmission spectrum of light of multiple longitudinal modes generated by the gain chip after being filtered by Etalon151 according to an embodiment I;
FIG. 4C is a diagram of the transmission spectrum of Etalon152 and the transmission spectrum of the light of multiple longitudinal modes generated by the gain chip after filtering with Etalon151 in the first embodiment;
FIG. 4D is a schematic diagram of the transmission spectrum and the longitudinal mode spectrum of Etalon151 with parameters adjusted according to the first embodiment;
fig. 4E is a schematic diagram of a transmission spectrum of Etalon152 after parameter adjustment and a transmission spectrum of Etalon151 after parameter adjustment of light of multiple longitudinal modes generated by the gain chip in the first embodiment;
FIG. 5A is a diagram showing the transmission spectrum and longitudinal mode spectrum of tunable Etalon in the third embodiment;
fig. 5B is a schematic diagram of the transmission spectrum and the longitudinal mode spectrum of the tunable Etalon with parameters adjusted in the third embodiment.
Detailed Description
The technical solution of the present invention is described below with reference to the accompanying drawings and embodiments.
An embodiment of the present invention provides an external cavity laser, whose structure is shown in fig. 2, including: a gain chip 11, a collimating mirror 14, a wavelength tunable selection component 15, a focusing lens 16, and a reflecting mirror 17.
The optical axes of the collimating mirror 14 and the focusing lens 16 coincide, the wavelength tunable selection component 15 is located between the collimating mirror 14 and the focusing lens 15, the wavelength tunable selection component 15 and the gain chip 11 are respectively located at two sides of the collimating mirror 14, the wavelength tunable selection component 15 and the reflection mirror 17 are respectively located at two sides of the focusing lens 17, the cavity surface 13 of the gain chip is located on the focal plane of the collimating lens 14, and the reflection mirror 17 is located on the focal plane of the focusing lens 16 and is perpendicular to the optical axis 20 of the focusing lens 16. The mirror 17 and the facet 12 of the gain chip 11 form the resonant cavity of the external cavity laser of an embodiment of the present invention.
In an embodiment of the invention, the wavelength tunable selection component 15 has an adjustable transmission spectrum. The transmission spectrum of the tunable wavelength selection component 15 is changed by adjusting the tunable wavelength selection component, so that the external cavity laser in the embodiment of the present invention outputs laser light with different wavelengths.
The gain chip 11 generates a light beam of multiple longitudinal modes, the light beam of the multiple longitudinal modes is emitted from the cavity surface 13 to the collimator 14, and the collimator 14 expands and collimates the light beam emitted from the cavity surface 14 to obtain a parallel light beam. The wavelength tunable selection component 15 filters the parallel light beam. The transmission spectrum of the wavelength tunable selection component 15 determines that light having a wavelength that coincides with the position of the transmission peak in the transmission spectrum is substantially completely transmitted through the wavelength tunable selection component 15, and light having a wavelength that does not coincide with the position of the transmission peak in the transmission spectrum is attenuated to a different degree when passing through the wavelength tunable selection component 15. The parallel light beam emitted from the collimator lens 14 is filtered by the wavelength tunable selection assembly 15 and then converged by the focusing lens 16 to the mirror 17, and the mirror 17 reflects the light beam toward the focusing lens 16. The light beam reflected by the reflector 17 sequentially passes through the focusing lens 16, the wavelength tunable selection component 15 and the collimating mirror 15 and then enters the gain chip from the cavity surface 13 of the gain chip 11, wherein in the process that the light beam returns to the gain chip 11 from the reflector 17, the wavelength tunable selection component 15 filters the light beam entering from the direction of the focusing lens 16 again, so that the light with the wavelength which is not coincident with the position of the transmission peak in the transmission spectrum of the tunable selection component 15 is attenuated again. As can be seen from the above description, in the embodiment of the present invention, in the process from the exit of the optical beam from the cavity surface 13 of the gain chip 11 to the return to the cavity surface 13 of the gain chip 11 again, light in the optical beam whose wavelength does not coincide with the position of the transmission peak in the transmission spectrum of the wavelength tunable selection component 15 is attenuated twice. In the resonant cavity formed by the cavity surface 12 of the gain chip and the reflector 17, the light beam can undergo multiple back-and-forth reflections between the cavity surface 12 of the gain chip 11 and the reflector 17, for the light whose wavelength is not coincident with the position of the transmission peak in the transmission spectrum of the wavelength tunable selection component 15, every time the light passes through the wavelength tunable selection component 15, the light is attenuated once, after multiple attenuations, only the light whose wavelength is coincident with the position of the transmission peak in the transmission spectrum of the wavelength tunable selection component 15 is basically in the resonant cavity, and when the energy of the light whose wavelength is coincident with the position of the transmission peak in the transmission spectrum of the wavelength tunable selection component 15 in the resonant cavity reaches the threshold value condition, the light is emitted from the cavity surface 12 of the gain chip 11. When the wavelength tuning of the external cavity laser is realized, the wavelength tunable selection component 15 is adjusted to change the transmission spectrum of the external cavity laser, and specifically, the wavelength tunable selection component 15 is adjusted to align the transmission peak position of the transmission spectrum of the external cavity laser to different longitudinal modes in the multi-longitudinal-mode laser generated by the gain chip 11. Preferably, the wavelength tunable selection component 15 has only one transmission peak in the transmission spectrum within the wavelength tuning range of the external cavity laser according to the embodiment of the present invention.
In the external cavity laser provided by the embodiment of the invention, the reflecting mirror is positioned at the focal plane of the focusing lens and is vertical to the optical axis of the focusing lens, and the reflecting mirror can basically reflect all the light incident on the reflecting surface of the reflecting mirror to the focusing mirror, so that the loss of the external cavity laser is very low. And because the threshold current of the external cavity laser is related to the loss of the external cavity laser, the larger the loss of the external cavity laser is, the larger the threshold current of the external cavity laser is, and the large threshold current causes the working performance, stability and reliability of the external cavity laser to be poor, so that the external cavity laser provided by the embodiment of the invention has good working performance, excellent stability and reliability due to very low loss. In addition, when the wavelength tuning is realized by the external cavity laser provided by the embodiment of the invention, the transmission spectrum of the external cavity laser is changed by adjusting the wavelength tunable selection component, and the transmission spectrum of the wavelength tunable selection component is very simple and fast to adjust, so that the wavelength tuning speed of the external cavity laser provided by the embodiment of the invention is fast, and the tuning control is simple.
In one embodiment, the wavelength tunable selection component 15 is specifically an adjustable Etalon with high finesse. Within the wavelength tuning range of the external cavity laser, the tunable Etalon has only one transmission peak in the transmission spectrum. Preferably, the adjustable Etalon is selected such that, after passing through the adjustable Etalon, a gain difference between a longitudinal mode of the multiple longitudinal modes that coincides with a position of a transmission peak in a transmission spectrum of the adjustable Etalon (referred to as a principal mode) and a longitudinal mode closest to the principal mode is at least 3 dB.
In another embodiment, as shown in fig. 3, the wavelength tunable selection component 15 is specifically composed of a first wavelength selective element 151 and a second wavelength selective element 152. The first wavelength selective element 151 filters the parallel light flux emitted from the collimator lens 14, and the second wavelength selective element 152 is located behind the second wavelength selective element 152 and filters the light flux emitted from the first wavelength selective element 151. It will be appreciated that the light reflected by the mirror 17 passes through the focusing lens 16, is filtered by the second wavelength selective element 152 and then by the first wavelength selective element 151. Wherein there is a coincident transmission peak position between the transmission spectrum of the first wavelength selective element 151 and the transmission spectrum of the second wavelength selective element 152, and the transmission peak position is adjustable. In this embodiment, at least one of the first wavelength selective element 151 and the second wavelength selective element 152 is adjusted to change the position of the coincident transmission peak so that the external cavity laser outputs laser light of different wavelengths.
In a further embodiment, the transmission spectrum of the first wavelength selective element 151 is a non-adjustable transmission spectrum and the transmission spectrum of the second wavelength selective element 152 is an adjustable transmission spectrum. In the present embodiment, the wavelength tuning function of the external cavity laser is achieved by adjusting the transmission spectrum of the second wavelength selective element 152, and specifically, adjusting the second wavelength selective element 152 causes the position of the transmission peak in the transmission spectrum of the second wavelength selective element 152 to be changed, thereby causing the position of the transmission peak coinciding between the transmission spectrum of the second wavelength selective element 152 and the transmission spectrum of the first wavelength selective element 151 to be changed. In this embodiment, since the transmission spectrum of the first wavelength selective element is not adjustable, which single-wavelength laser light the external cavity laser of this embodiment can output is determined by the transmission spectrum of the first wavelength selective element 151, and each transmission peak position in the transmission spectrum of the first wavelength selective element 151 corresponds to one single-wavelength laser light the external cavity laser outputs. In some scenarios, the external cavity laser only needs to be tuned between certain specific wavelengths, and therefore, it may suffice to select the first wavelength selective element 151 whose transmission peak position of the transmission spectrum coincides with the above specific wavelengths. In another embodiment, the transmission spectrum of the first wavelength selective element 151 is tunable, while the transmission spectrum of the second wavelength selective element 152 is non-tunable.
In yet another embodiment, the transmission spectrum of the first wavelength selective element 151 and the transmission spectrum of the second wavelength selective element 152 are both tunable transmission spectra. In this embodiment, the wavelength tuning function of the external cavity laser is achieved by adjusting the transmission spectrum of the first wavelength selective element 151 and the transmission spectrum of the second wavelength selective element 152 such that there is a coincident transmission peak position between the transmission spectrum of the first wavelength selective element 151 and the transmission spectrum of the second wavelength selective element 152. In this embodiment, since the transmission spectrum of the first wavelength selective element 151 and the transmission spectrum of the second wavelength selective element 152 are both adjustable, the external cavity laser can output laser light of any single wavelength within the wavelength tuning range of the external cavity laser.
In a specific embodiment, the aforementioned first wavelength selective element 151 and the second wavelength selective element 152 may each be Etalon. In particular, when it is required that the transmission spectrum of any one of the first wavelength selective element 151 and the second wavelength selective element 152 is adjustable, the wavelength selective element may be specifically tunable Etalon. The adjustable Etalon applicable to the embodiment of the invention has at least the following types: thermoregulated Etalon, liquid crystal adjustable Etalon, and pitch adjustable Etalon.
In order to further reduce loss, the reflecting mirror in the external cavity laser provided by the embodiment of the invention is plated with the reflection increasing film.
In order to further increase the flexibility of tuning the wavelength of the external cavity laser, the gain chip 11 in the external cavity laser provided in the embodiment of the present invention includes a phase shift region, and after the phase shift region is introduced into the gain chip 11, the gain chip 11 can adjust the distribution of the longitudinal mode according to the change of the injection current.
In order to better understand the wavelength tuning process of the external cavity laser according to the embodiment of the present invention, three specific implementations of the wavelength tunable selection component 15 are described as examples.
Example one
As shown in fig. 3, the wavelength tunable selection component 15 is specifically composed of two wavelength selection elements 151 and 152, and both the wavelength selection elements 151 and 152 are specifically tunable etalons, for convenience of description, in this embodiment, the wavelength selection element 151 is directly referred to as tunable etalons 151, and the wavelength selection element 152 is directly referred to as tunable etalons 152.
In the present embodiment, the cavity length (distance from the cavity surface 12 of the gain chip 11 to the mirror 17) L of the external cavity laser is 2cm, the wavelength of the light of the multiple longitudinal modes generated by the gain chip 11 is distributed in the C band (1530 nm to 1565 nm), and the longitudinal mode interval Δ λ is set to the longitudinal mode intervalmode=0.06 nm. The reflectance R of the adjustable Etalon151 was 0.9, the gap length was 2.9995mm, and the gap refractive index was 1. Etalon152 had a reflectivity of 0.9, a gap length of 22.4851 μm, and a gap index of refraction of 1.4581.
As shown in fig. 4A, the dashed lines indicate the respective longitudinal modes (each corresponding to a wavelength), and the solid lines indicate the transmission spectrum of tunable Etalon 151. As can be seen from fig. 4A, the longitudinal mode with wavelength 1549.72nm (shown by the 4 th dashed line after 1549.5nm in fig. 4A) coincides with one transmission peak position (transmission peak at 1549.72 nm) in the transmission spectrum of tunable Etalon151, and the longitudinal mode with wavelength 1550.92nm (shown by the 2 nd dashed line before 1551nm in fig. 4A) coincides with the other transmission peak position (transmission peak at 1550.92 nm) in the transmission spectrum of tunable Etalon 151. After light entering each longitudinal mode of the adjustable Etalon151 passes through the adjustable Etalon151, only light of the longitudinal mode having a wavelength coincident with a transmission peak position in the transmission spectrum of the adjustable Etalon151 passes through the adjustable Etalon151 without loss, and light of the longitudinal mode having a wavelength not coincident with a transmission peak position in the transmission spectrum of the Etalon151 is attenuated to a different degree when passing through the adjustable Etalon 151. Fig. 4B shows the transmission spectrum of the light of the multiple longitudinal modes emitted from the gain chip 11 after being filtered by the tunable Etalon151, and it is clear from this figure that the power of the light of the longitudinal mode with the wavelength of 1549.72nm and the power of the light of the longitudinal mode with the wavelength of 1550.92nm after passing through the tunable Etalon151 are substantially unchanged compared to the power before entering the tunable Etalon, while the power of the light of the other longitudinal modes is greatly attenuated after passing through the tunable Etalon 151.
Tunable Etalon152 further filters the light transmitted from tunable Etalon 151. As shown in fig. 4C, the dashed line in the figure indicates the transmission spectrum of the adjustable Etalon152, and the solid line in the figure indicates the transmission spectrum of the light of the multiple longitudinal modes emitted from the gain chip 11 after being filtered by the adjustable Etalon 151. As is clear from fig. 4C, the 1549.72nm longitudinal mode coincides with a transmission peak position (transmission peak position is 1549.72 nm) in the transmission spectrum of tunable Etalon152, so that only the longitudinal mode with a wavelength of 1579.72nm of the light transmitted from tunable Etalon151 passes through tunable Etalon152 substantially without loss, while the light of the other longitudinal modes is greatly attenuated when passing through tunable Etalon 152. After the light of multiple longitudinal modes emitted from the gain chip 11 passes through the tunable Etalon151 and the tunable Etalon152 in sequence, there is substantially only light of one longitudinal mode, and the light of the other longitudinal modes is substantially not attenuated, so that the light emitted from the cavity surface 12 of the gain chip 11 will be laser light of a single longitudinal mode. The process of filtering out light of one longitudinal mode from light of multiple longitudinal modes generated by the gain chip 11 by the adjustable Etalon151 and the adjustable Etalon152 is a mode selection process of the external cavity laser.
Transmission peak position λ of EtalonmDetermined by equation (1):
wherein n is the gap refractive index of Etalon, d is the gap distance of Etalon, theta is the included angle between the light beam incident to Etalon and Etalon, and m is a positive integer. For tunable Etalon, n, d, and θ are adjustable, while for non-tunable Etalon, n, d, and θ are fixed, so that the transmission peak position of tunable Etalon can be changed, while the transmission peak position of non-tunable Etalon is not.
In this embodiment, when the external cavity laser is required to output laser light with another wavelength (for example, laser light with an output wavelength of 1549.78 nm), at least one of n, d and θ of adjustable etalons 151 and 152 may be adjusted, so that the transmission spectra of adjustable etalons 151 and 152 are both changed, and the changed transmission spectra of adjustable etalons 151 and 152 have a coincident transmission peak only at a wavelength of 1549.78 nm. For example, by increasing the gap distance d of adjustable Etalon151 and fine-tuning the gap index n of adjustable Etalon152, the transmission spectrum of adjustable Etalon151 and the transmission spectrum of adjustable Etalon152 may have coincident transmission peaks only at 1549.78 nm. As shown in fig. 4D, the dashed lines indicate the longitudinal modes, the solid lines indicate the transmission spectrum of the tunable Etalon151 with increased D, and it can be seen that only the longitudinal modes with wavelengths of 1549.78nm (as shown by the fifth dashed line at 1549.5nm in fig. 4D) and 1550.98nm (as shown by the first dashed line at 1551nm in front of the Etalon151 in fig. 4D) coincide with the two transmission peak positions in the transmission spectrum of Etalon 151. As shown in fig. 4E, a solid line in the figure indicates the transmission spectrum of the modulated Etalon151 after the light of the multiple longitudinal modes emitted from the gain chip 11 is increased by d, a dashed line in the figure indicates the transmission spectrum of the modulated Etalon152 after n is fine-tuned, and it can be seen from the figure that the longitudinal mode with a wavelength of 1549.78nm coincides with one transmission peak position (the transmission peak is located at 1549.78 nm) in the transmission spectrum of Etalon 152. As can be seen from fig. 4D and 4E, after the light of multiple longitudinal modes emitted from the gain chip 11 passes through the tunable Etalon151 and the tunable Etalon152 in sequence, substantially only one longitudinal mode with a wavelength of 1579.78nm is emitted, and the light of the other longitudinal modes is substantially not attenuated, so that the laser light with a wavelength of 1579.78nm is emitted from the cavity surface 12 of the gain chip 11.
In the present embodiment, since the wavelength selective elements 151 and 152 are both tunable etalons, the external cavity laser of the present embodiment can output laser light of any single longitudinal mode.
Example two
In the embodiment, the wavelength tunable selection component 15 is specifically composed of two wavelength selection elements 151 and 152, and both the wavelength selection elements 151 and 152 are specifically etalons, and one of the etalons is tunable etalons, and the other is non-tunable etalons.
In this embodiment, only one of the wavelength selective elements 151 and 152 is the adjustable Etalon, so that the external cavity laser in this embodiment outputs laser light with one wavelength to output laser light with another wavelength by adjusting the adjustable Etalon, and the method for adjusting the adjustable Etalon refers to the related description in the first embodiment, and is not described herein again.
In this embodiment, since one of the wavelength selective elements 151 and 152 is the non-tunable Etalon, which wavelengths of laser light can be output by the external cavity laser in this embodiment depends on the non-tunable Etalon. The transmission spectrum of the non-tunable Etalon cannot be changed, and only the light of the longitudinal mode which coincides with the transmission peak position in the transmission spectrum of the non-tunable Etalon among the light of the multiple longitudinal modes generated by the gain chip 11 of the external cavity laser may finally form laser light to be emitted from the cavity surface 12 of the gain chip 11.
EXAMPLE III
In this embodiment, the wavelength tunable selection component 15 is specifically an adjustable Etalon. In order to enable the external cavity laser of the present embodiment to output laser light in a single longitudinal mode, the tunable Etalon in the present embodiment needs to be tunable Etalon with high finesse. Specifically, only one transmission peak in the tunable Etalon transmission spectrum is selected within the wavelength tuning range of the external cavity laser. Preferably, the adjustable Etalon is selected such that a gain difference between a longitudinal mode (for convenience of description, this longitudinal mode is referred to as a main mode) coinciding with a position of a transmission peak in the transmission spectrum and a longitudinal mode closest to the main mode after passing through the adjustable Etalon is equal to or greater than 3 dB.
In the present embodiment, the cavity length (the distance from the cavity surface 12 of the gain chip 11 to the mirror 16) L of the external cavity laser is 2cm, the wavelength of the light of the multiple longitudinal modes generated by the gain chip 11 is distributed in the C band (1530 nm to 1565 nm), and the longitudinal mode interval Δ λ is set to the longitudinal mode intervalmode=0.06nm。
As shown in fig. 5A, the solid line in the figure indicates the transmission spectrum of the tunable Etalon in the present embodiment, and the broken line in the figure indicates each longitudinal mode generated by the gain chip 11. As can be seen in FIG. 5A, the transmission peak of tunable Etalon is at a wavelength of 1549.72nm (indicated by the fourth dashed line behind 1549.5nm in FIG. 5A), and the longitudinal mode at 1549.72nm coincides exactly with the position of the transmission peak. Of the light incident on each longitudinal mode of the tunable Etalon of this embodiment, only the light of the longitudinal mode with the wavelength of 1549.72nm passes through the tunable Etalon of this embodiment without loss, while the light of the other longitudinal modes is attenuated to a great extent when passing through the Etalon of this embodiment, and therefore, the laser light with the wavelength of 1549.72nm is finally emitted from the cavity surface 12 of the gain chip 11.
When the laser needs to output laser with the wavelength of 1551.28nm, at least one parameter of n, d and theta of the adjustable Etalon in the embodiment is adjusted, so that the position of the transmission peak of the adjustable Etalon in the embodiment is shifted to 1551.28nm, and the transmission peak is overlapped with a longitudinal mode with the wavelength of 1551.28 nm. As shown in fig. 5B, the parameters shown by the solid line in the graph are the transmission spectrum of the adjusted tunable Etalon, and the broken lines show the longitudinal modes generated by the gain chip 11. As can be seen from fig. 5B, after the parameters of the adjustable Etalon in this embodiment are adjusted, the position of the transmission peak of the adjustable Etalon in this embodiment has been shifted to 1551.28nm (as shown by the fourth dotted line in front of 1551.5nm in fig. 5B), so that the external cavity laser can output laser light with a wavelength of 1551.28nm after the parameters of the adjustable Etalon in this embodiment are adjusted.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (8)
1. An external cavity laser, comprising: the device comprises a gain chip, a collimating mirror, a wavelength tunable selection component, a focusing lens and a reflecting mirror;
the gain chip and the wavelength tunable selection component are respectively positioned at two sides of the collimating mirror, and one cavity surface of the gain chip is positioned on a focal plane of the collimating mirror;
the gain chip is used for generating multi-longitudinal-mode light beams, wherein the multi-longitudinal-mode light beams are emitted from the cavity surface;
the collimating lens is used for expanding and collimating the multi-longitudinal-mode light beam emitted from the cavity surface of the gain chip to obtain a parallel light beam;
the wavelength tunable selection component is provided with an adjustable transmission spectrum and is used for filtering the parallel light beams; wherein the different transmission spectra correspond to the external cavity laser outputting laser light of different wavelengths;
the focusing lens is used for converging the filtered parallel light beams to the reflecting mirror;
the reflector is positioned on the focal plane of the focusing lens, is vertical to the optical axis of the focusing lens, and is used for reflecting the light beams incident to the reflecting surface of the reflector to the focusing lens;
the gain chip comprises a phase shift area, and the distribution of longitudinal modes is adjusted according to the change of injection current;
wherein the adjustable transmission spectrum of the wavelength tunable selection component has only one transmission peak within the wavelength tuning range of the external cavity laser;
and the gain difference between the light of the longitudinal mode with the wavelength coincident with the position of the transmission peak and the light of the longitudinal mode closest to the position of the transmission peak in the multi-longitudinal-mode light beam after passing through the wavelength tunable selection component is more than or equal to 3 dB.
2. The external cavity laser of claim 1, wherein the wavelength tunable selection component comprises:
a first wavelength selective element for filtering the parallel light beam;
the second wavelength selective element is positioned on the light beam output by the first wavelength selective element for filtering; wherein there is a coincident transmission peak position between the transmission spectrum of the second wavelength selective element and the transmission spectrum of the first wavelength selective element, and the transmission peak position is adjustable.
3. The external cavity laser according to claim 2, wherein the transmission spectrum of the first wavelength selective element is in particular an adjustable transmission spectrum and the transmission spectrum of the second wavelength selective element is in particular an adjustable transmission spectrum.
4. The external cavity laser according to claim 3, wherein the transmission spectrum of the first wavelength selective element is in particular a non-tunable transmission spectrum and the transmission spectrum of the second wavelength selective element is in particular a tunable transmission spectrum; or,
the transmission spectrum of the first wavelength selective element is in particular an adjustable transmission spectrum and the transmission spectrum of the second wavelength selective element is in particular a non-adjustable transmission spectrum.
5. An external cavity laser as claimed in any one of claims 2 to 4 wherein said first and second wavelength selective elements are each in particular an etalon.
6. An external cavity laser as claimed in claim 5 wherein when the transmission spectrum of any one of the first and second wavelength selective elements is tunable, the wavelength selective element is in particular a tunable etalon.
7. An external cavity laser as claimed in claim 6 wherein said tuneable etalon is particularly one of a thermoregulated etalon, a liquid crystal tuneable etalon and a pitch tuneable etalon.
8. An external cavity laser as claimed in any one of claims 1 to 4 wherein said mirror is coated with a reflection enhancing film.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/CN2012/078002 WO2014000311A1 (en) | 2012-06-30 | 2012-06-30 | External cavity laser |
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| CN103814488A CN103814488A (en) | 2014-05-21 |
| CN103814488B true CN103814488B (en) | 2016-09-28 |
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| WO (1) | WO2014000311A1 (en) |
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| CN103515840A (en) * | 2013-08-07 | 2014-01-15 | 苏州旭创科技有限公司 | External-cavity laser device with tunable wave length |
| CN215377956U (en) * | 2021-06-21 | 2021-12-31 | 苏州旭创科技有限公司 | External cavity laser |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1357951A (en) * | 2000-11-02 | 2002-07-10 | 古河电气工业株式会社 | Semiconductor laser module, laser unit and Raman amplifier |
| CN1509507A (en) * | 2001-03-16 | 2004-06-30 | 英特尔公司 | Adjustable extemal cavity laser |
| CN101557076A (en) * | 2009-05-22 | 2009-10-14 | 中国科学院国家授时中心 | Shakeproof external cavity semiconductor laser |
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| US6822979B2 (en) * | 2001-07-06 | 2004-11-23 | Intel Corporation | External cavity laser with continuous tuning of grid generator |
| CN1225824C (en) * | 2003-07-11 | 2005-11-02 | 清华大学 | Composite external chamber stepping toning semiconductor laser and its toning method |
| GB0823084D0 (en) * | 2008-12-18 | 2009-01-28 | Renishaw Plc | Laser Apparatus |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1357951A (en) * | 2000-11-02 | 2002-07-10 | 古河电气工业株式会社 | Semiconductor laser module, laser unit and Raman amplifier |
| CN1509507A (en) * | 2001-03-16 | 2004-06-30 | 英特尔公司 | Adjustable extemal cavity laser |
| CN101557076A (en) * | 2009-05-22 | 2009-10-14 | 中国科学院国家授时中心 | Shakeproof external cavity semiconductor laser |
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| WO2014000311A1 (en) | 2014-01-03 |
| CN103814488A (en) | 2014-05-21 |
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