Tunable narrow linewidth high-speed laser and modulation method thereof

Abstract

The present disclosure provides a tunable narrow linewidth high-speed laser and a modulation method thereof, which comprises: a substrate (1); a first temperature control carrier (2), a second temperature control carrier (3), a third temperature control carrier (4), a standard carrier (5) and a fourth temperature control carrier (6), which are sequentially and spacedly arranged on the substrate (1) along the light emitting direction of the laser chip; a laser chip, which comprises a gain region (7), a grating region (8) and a modulation region (9), and is sequentially arranged on the fourth temperature control carrier (6) along the light emitting direction; a collimating lens (10) arranged on the standard carrier (5); a first F-P etalon (11) and a second F-P etalon (12), wherein the first F-P etalon (11) is arranged on the third temperature control carrier (4), and the second F-P etalon (12) is arranged on the second temperature control carrier (3); and a reflection crystal (13) arranged on the first temperature control carrier (2).

Description

Technical Field

[0001] This disclosure relates to the field of laser technology, and in particular to a tunable narrow-linewidth high-speed laser and its modulation method. Background Technology

[0002] With the increasing speed of optical communication systems, the demand for and requirements of high-speed lasers are growing. High-speed direct-tuned lasers offer advantages such as low power consumption and low cost, making them one of the main candidates for applications such as passive optical networks, short-range communication, and data centers. However, for wavelength division multiplexing (WDM) scenarios, tunable lasers can reduce laser backup costs. The tuning range of typical DBR lasers is limited to around tens of nanometers due to the injection current in the grating region, while for LWDM and CWDM applications, the wavelength typically covers tens of nanometers. While monolithic lasers using sampling grating designs can meet the wavelength requirements, their linewidth is around 100kHz, making further narrowing of the linewidth difficult. Laser solutions that simultaneously possess wide-range tunability, narrow linewidth, and high speed are even rarer. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] In view of the above problems, this disclosure provides a tunable narrow linewidth high-speed laser and its modulation method, so as to at least partially solve the problems of small wavelength tuning range, large linewidth and low modulation rate of current lasers.

[0005] (II) Technical Solution

[0006] One aspect of this disclosure provides a tunable narrow-linewidth high-speed laser, comprising: a substrate; a first temperature control carrier, a second temperature control carrier, a third temperature control carrier, a standard carrier, and a fourth temperature control carrier, disposed sequentially and at intervals on the substrate along the light emission direction of a laser chip; a laser chip, including a gain region, a grating region, and a modulation region, disposed sequentially on the fourth temperature control carrier along the light emission direction; a collimating lens disposed on the standard carrier; a first FP etalon and a second FP etalon, the first FP etalon being disposed on the third temperature control carrier and the second FP etalon being disposed on the second temperature control carrier; and a reflecting crystal disposed on the first temperature control carrier.

[0007] Optionally, the feedback light end face of the reflective crystal and the grating region constitute the resonant cavity of the laser.

[0008] Optionally, the laser chip has anti-reflection coatings on both end faces along the light emission direction; the collimating lens has an anti-reflection coating on its entirety; the first FP etalon and the second FP etalon have high-reflection coatings on both end faces along the light emission direction; the feedback light end face of the reflective crystal has a reflective coating, and the end face opposite to the feedback light end face has an anti-reflection coating.

[0009] Optionally, the material structure of the grating region is an active layer and / or a passive layer.

[0010] Optionally, the grating region may contain a single-period grating or multiple gratings with different periods.

[0011] A second aspect of this disclosure provides a modulation method for a tunable narrow-linewidth high-speed laser, applied to the tunable narrow-linewidth high-speed laser, comprising: injecting current into a gain region to generate laser light in the gain region, which is then irradiated by a collimating lens; collimating the laser light through the collimating lens so that the laser light enters a first FP etalon and a second FP etalon; filtering the laser light through the first FP etalon and the second FP etalon and transmitting it to a reflecting crystal; reflecting the laser light through the reflecting crystal so that the laser light is reflected back to the gain region along the output direction, whereby the gain region amplifies and outputs the laser light.

[0012] Optionally, the method further includes: forming a resonant cavity of the laser by means of the feedback light end face of the reflective crystal and the grating region; after the laser is reflected back to the gain region, a portion of the laser is reflected into the resonant cavity through the grating region, and another portion of the laser is output through the modulation region.

[0013] Optionally, filtering the laser using the first FP etalon and the second FP etalon includes: based on the different maximum transmission peak values ​​of the first FP etalon and the second FP etalon at different times, filtering the wavelength output at the transmission peak position in the laser to obtain a single-wavelength signal; wherein, by changing the injection current of the third temperature control carrier and the second temperature control carrier, the temperature of the first FP etalon and the second FP etalon is changed, causing the maximum transmission peak values ​​of the first FP etalon and the second FP etalon to shift.

[0014] Optionally, the method further includes: changing the temperature of the reflective crystal by changing the injection current of the first temperature control carrier, thereby changing the phase of the laser in the resonant cavity.

[0015] Optionally, the step of outputting another portion of the laser through the modulation region includes: applying a current signal to the modulation region, the current signal being a high-level signal and a low-level signal that alternately change at a preset interval; when the current signal is high-level, the modulation region amplifies the laser; when the current signal is low-level, the modulation region absorbs the laser.

[0016] (III) Beneficial Effects

[0017] 1. The tunable narrow linewidth high-speed laser and its modulation method provided in this disclosure, by setting a first FP standard and a second FP standard, and combining the resonant cavity formed by the feedback light end face of the reflective crystal and the grating region, the wavelength at the transmission peak position is amplified and output, thereby achieving linewidth narrowing. At the same time, changing the second temperature control carrier and the third temperature control carrier achieves wavelength tuning over a wide range.

[0018] 2. The tunable narrow-linewidth high-speed laser and its modulation method disclosed herein achieve high-speed modulation by using two current signals of different levels (high and low) in the modulation region to output optical signals with different optical powers. Attached Figure Description

[0019] To gain a more complete understanding of this disclosure and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, wherein:

[0020] Figure 1 The schematic diagram illustrates a structural schematic of a tunable narrow-linewidth high-speed laser provided in an embodiment of this disclosure;

[0021] Figure 2 The schematic illustration shows the reflection spectrum of a grating region comprising a single-period grating according to an embodiment of the present disclosure;

[0022] Figure 3 The schematic illustration shows the reflection spectrum of a grating region composed of gratings with two different periods, provided in an embodiment of this disclosure.

[0023] Figure 4 The transmission spectrum of a single FP etalon provided in an embodiment of this disclosure is illustrated schematically;

[0024] Figure 5 The superimposed transmission spectrum of two FP etalons provided in an embodiment of this disclosure is illustrated schematically.

[0025] Explanation of reference numerals in the attached figures:

[0026] 1-Substrate;

[0027] 2-First temperature control carrier;

[0028] 3-Second temperature control carrier;

[0029] 4-Third temperature control carrier;

[0030] 5-Standard carrier;

[0031] 6-Fourth temperature control carrier;

[0032] 7-Gain Region;

[0033] 8-Raster area;

[0034] 9-Modulation region;

[0035] 10 - Collimating lens;

[0036] 11-First FP etalon;

[0037] 12-Second FP standard etalon;

[0038] 13-Reflective crystal. Detailed Implementation

[0039] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0040] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0041] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0042] Figure 1 The schematic diagram illustrates the structure of a tunable narrow-linewidth high-speed laser provided in an embodiment of the present disclosure.

[0043] like Figure 1As shown, the tunable narrow-linewidth high-speed laser of this disclosure includes: a substrate 1; a first temperature control carrier 2, a second temperature control carrier 3, a third temperature control carrier 4, a standard carrier 5, and a fourth temperature control carrier 6, which are sequentially and spaced apart on the substrate 1 along the light emission direction of the laser chip; a laser chip, including a gain region 7, a grating region 8, and a modulation region 9, which are sequentially disposed on the fourth temperature control carrier 6 along the light emission direction; a collimating lens 10 disposed on the standard carrier 5; a first FP etalon 11 and a second FP etalon 12, with the first FP etalon 11 disposed on the third temperature control carrier 4 and the second FP etalon 12 disposed on the second temperature control carrier 3; and a reflective crystal 13 disposed on the first temperature control carrier 2.

[0044] In this embodiment, the first temperature control carrier 2, the second temperature control carrier 3, the third temperature control carrier 4 and the fourth temperature control carrier 6 can change their surface temperature by changing their injection voltage or current, thereby controlling the temperature of the object carried above the carrier, thus realizing flexible control of the temperature of different areas of the entire laser.

[0045] The materials of modulation region 9 and gain region 7 can be the same or different. When the materials of modulation region 9 and gain region 7 are the same, they will also amplify and absorb the input optical signal. Therefore, when modulation region 9 is modulated with two current signals of different levels, where the high current corresponds to '1' in the digital signal and the low current corresponds to '0', modulation region 9 amplifies the laser under the drive of the high current signal, resulting in higher optical power. Under the drive of the low current, modulation region 9 cannot amplify the laser, thus resulting in absorption and reducing the output optical power of the laser. Therefore, by rapidly alternating between the high and low currents at a preset interval, the laser outputs optical signals with different optical powers, thereby achieving high-speed digital signal output.

[0046] Furthermore, the feedback light end face of the reflective crystal 13 and the grating region 8 constitute the resonant cavity of the laser.

[0047] The function of the resonant cavity is to preferentially amplify light of a specific frequency and consistent direction, while suppressing light of other frequencies and directions. This disclosure achieves linewidth narrowing and wavelength tuning by employing an external cavity structure and a mode selection device composed of multiple etalons. Specifically, the free spectral range (FSR) of the transmission spectra of the first FP etalon 11 and the second FP etalon 12 are different. According to the vernier effect, only one maximum transmission peak exists at any given time for the first FP etalon 11 and the second FP etalon 12. The light transmitted in the resonant cavity is filtered by the two etalons, and after multiple amplifications in the resonant cavity, only the wavelength at the transmission peak position is amplified and output, thereby achieving single-wavelength output and linewidth narrowing. At the same time, by changing the temperature of the first FP etalon 11 and the second FP etalon 12, the maximum transmission peak of the transmission spectrum composed of the two etalons shifts, thereby completing the lasing of another wavelength, thus achieving a wide range of wavelength tuning.

[0048] Optionally, the laser chip has anti-reflection coatings on both end faces along the light emission direction; the collimating lens 10 is coated with an anti-reflection coating; the first FP etalon 11 and the second FP etalon 12 have high-reflectivity coatings on both end faces along the light emission direction; the feedback light end face of the reflective crystal 13 is coated with a reflective coating, the feedback light end face being the left end face of the reflective crystal used to reflect the laser, and the end face opposite to the feedback light end face is coated with an anti-reflection coating. The anti-reflection coating increases the light transmission performance of the lens; the high-reflectivity coating utilizes the fact that when light passes through multiple media, reflection and transmission occur at the interfaces of each medium. When the thickness of the multiple media films meets certain requirements, i.e., when the reflected light satisfies constructive interference, the reflectivity is increased; the reflective coating improves the reflectivity of the optical surface, increases the brightness of the backlight module, and reduces the light source loss.

[0049] In this embodiment of the disclosure, the material structure of the grating region 8 is an active layer and / or a passive layer.

[0050] In this embodiment of the disclosure, the grating region 8 includes a single-period grating or includes multiple gratings with different periods.

[0051] Figure 2 The schematic illustration shows the reflection spectrum of a grating region 8 comprising a single-period grating provided in an embodiment of the present disclosure.

[0052] like Figure 2 As shown, when the grating region contains only a single-period grating, its wavelength coverage of the reflection spectrum is relatively small.

[0053] Figure 3 The schematic illustration shows the reflection spectrum of a grating region 8 composed of two gratings with different periods, provided in an embodiment of the present disclosure.

[0054] like Figure 3As shown, by using multiple gratings with different periods, their reflection spectra can be superimposed to each other, which can improve the wavelength coverage of the reflection spectrum of grating region 8, so that the reflectivity of grating region 8 for light signals of different wavelengths within the tunable wavelength range is not much different.

[0055] Another aspect of this disclosure provides a modulation method for a tunable narrow-linewidth high-speed laser, applied to a tunable narrow-linewidth high-speed laser, specifically including:

[0056] A current is injected into the gain region 7 to generate laser light, which is then irradiated by the collimating lens 10. The laser light is collimated by the collimating lens 10 and enters the first FP etalon 11 and the second FP etalon 12. The laser light is filtered by the first FP etalon 11 and the second FP etalon 12 and transmitted to the reflecting crystal 13. The laser light is reflected by the reflecting crystal 13 and reflected back to the gain region 7 along the light output direction. The gain region 7 then amplifies and outputs the laser light.

[0057] In this embodiment of the disclosure, the method further includes: forming a resonant cavity of the laser by means of the feedback light end face of the reflective crystal 13 and the grating region 8; after the laser is reflected back to the gain region 7, a portion of the laser is reflected into the resonant cavity through the grating region 8, and the other portion of the laser is output through the modulation region 9.

[0058] The above completes one round-trip gain process for the laser. After multiple rounds of the above process, the laser produces a stable laser output.

[0059] Furthermore, filtering the laser using the first FP standard 11 and the second FP standard 12 includes:

[0060] Based on the fact that the maximum transmission peak values ​​of the first FP etalon 11 and the second FP etalon 12 are different at different times, the wavelength at the transmission peak position in the laser is filtered and output to obtain a single wavelength signal; wherein, by changing the injection current of the third temperature control carrier 4 and the second temperature control carrier 3, the temperature of the first FP etalon 11 and the second FP etalon 12 is changed, causing the maximum transmission peak values ​​of the first FP etalon 11 and the second FP etalon 12 to shift.

[0061] The above describes the specific process of laser wavelength tuning. By adjusting the temperature of the first FP etalon 11 and the second FP etalon 12, the position of the transmission spectrum is changed, thereby achieving a wide range of laser wavelength tuning.

[0062] Figure 4 The transmission spectrum of a single FP etalon provided in an embodiment of this disclosure is illustrated schematically.

[0063] Figure 5 The superimposed transmission spectrum of two FP etalons provided in an embodiment of this disclosure is illustrated schematically.

[0064] like Figure 4 and Figure 5 As shown, the spectral range of the superimposed transmission spectrum of two FP etalons is larger than that of a single FP etalon. Therefore, this disclosure achieves wide-range wavelength tuning by setting the first FP etalon 11 and the second FP etalon 12 to filter the laser. At the same time, since there is a maximum transmission peak at the same time after superposition, only the wavelength at the transmission peak position is amplified and output, thereby achieving single-wavelength output and linewidth narrowing.

[0065] Furthermore, by changing the injection current of the first temperature control carrier 2, the temperature of the reflective crystal 13 is changed, thereby altering the phase of the laser in the resonant cavity.

[0066] By changing the temperature of the reflective crystal and its refractive index, the phase of the light changes when the laser passes through materials with different refractive indices. As a result, the wavelength and amplitude also change, thereby achieving continuous wavelength tuning and improving the mode stability of the laser.

[0067] Furthermore, outputting another portion of the laser through modulation region 9 includes: applying a current signal to modulation region 9, the current signal being a high-level signal and a low-level signal that alternately change according to a preset interval; when the current signal is high-level, modulation region (9) amplifies the laser; when the current signal is low-level, modulation region (9) absorbs the laser.

[0068] Example 1:

[0069] The laser chip includes a gain region 7, a grating region 8, and a modulation region 9. The gain region 7 has a length of 100 μm; the grating region 8 has a length of 50 μm and a grating coupling coefficient of 20000 / m, and its reflection spectrum is as follows: Figure 2 As shown; the length of modulation region 9 is set to 100um, and the same material as gain region 7 is used.

[0070] Both end faces of the first FP etalon 11 and the second FP etalon 12 are coated with a 90% high-reflectivity film. The transmission spectrum of the second FP etalon 12 is as follows: Figure 4 As shown, the superimposed transmission spectra of the first FP etalon 11 and the second FP etalon 12 are as follows: Figure 5 As shown.

[0071] The reflective crystal 13 has a reflective film with a reflectivity of 90% on the feedback light end face and an anti-reflective film with a reflectivity of less than 0.1% on the end face opposite to the feedback light end face.

[0072] The collimating lens 10 is coated with an anti-reflective coating with an overall reflectivity of less than 0.1%.

[0073] According to the tunable narrow-linewidth high-speed laser and its modulation method provided in this disclosure, the feedback light end face of the reflective crystal 13 and the grating region 8 constitute the resonant cavity of the laser. By changing the injection current of the second temperature control carrier 3 and the third temperature control carrier 4, the temperatures of the first FP etalon 11 and the second FP etalon 12 are changed, thereby achieving wide-range wavelength tuning and linewidth narrowing. Simultaneously, changing the injection current of the first temperature control carrier 2 changes the temperature of the reflective crystal 13, achieving continuous wavelength tuning and improving the mode stability of the laser. Furthermore, applying high and low level current signals to the modulation region amplifies and absorbs the laser light respectively, thereby outputting optical signals with different optical powers, realizing high-speed digital signal output, i.e., high-speed modulation of the laser.

[0074] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

[0075] Although this disclosure has been shown and described with reference to specific exemplary embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made to this disclosure without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents. Therefore, the scope of this disclosure should not be limited to the above embodiments, but should be defined not only by the appended claims, but also by their equivalents.

Claims

1. A tunable narrow linewidth high speed laser, characterized in that, It comprises: a substrate (1); a first temperature control carrier (2), a second temperature control carrier (3), a third temperature control carrier (4), a standard carrier (5) and a fourth temperature control carrier (6) are sequentially and spacedly arranged on the substrate (1) along the light emitting direction of the laser chip; a laser chip comprising a gain region (7), a grating region (8) and a modulation region (9) is sequentially arranged on the fourth temperature control carrier (6) along the light emitting direction; a collimating lens (10) is arranged on the standard carrier (5); a first F-P etalon (11) is arranged on the third temperature control carrier (4), and a second F-P etalon (12) is arranged on the second temperature control carrier (3); a reflection crystal (13) is arranged on the first temperature control carrier (2).

2. The laser of claim 1, wherein, The feedback light end face of the reflection crystal (13) and the grating region (8) form the resonant cavity of the laser.

3. The laser of claim 1, wherein, The two end faces of the laser chip along the light emitting direction are coated with an anti-reflection film; the whole collimating lens (10) is coated with an anti-reflection film; the two end faces of the first F-P etalon (11) and the second F-P etalon (12) along the light emitting direction are coated with a high reflection film; the feedback light end face of the reflection crystal (13) is coated with a reflection film, and the end face opposite to the feedback light end face is coated with an anti-reflection film.

4. The laser of claim 1, wherein, The material structure of the grating region (8) is an active layer and / or a passive layer.

5. The laser of claim 1, wherein, The grating region (8) contains a single period grating or contains multiple gratings with different periods.

6. A modulation method of a tunable narrow-linewidth high-speed laser, applied to the tunable narrow-linewidth high-speed laser according to any one of claims 1 to 5, characterized in that, It comprises: injecting current into the gain region (7) to make the gain region (7) generate laser which irradiates the collimating lens (10); collimating the laser through the collimating lens (10) to make the laser enter the first F-P etalon (11) and the second F-P etalon (12); filtering the laser through the first F-P etalon (11) and the second F-P etalon (12) and transmitting it to the reflection crystal (13); reflecting the laser through the reflection crystal (13) to make the laser reflect back to the gain region (7) along the light emitting direction, and amplifying and outputting the laser by the gain region (7).

7. The method of claim 6, wherein, It further comprises: forming the resonant cavity of the laser by the feedback light end face of the reflection crystal (13) and the grating region (8); after the laser reflects back to the gain region (7), a part of the laser is reflected into the resonant cavity through the grating region (8), and another part of the laser is outputted through the modulation region (9).

8. The method of claim 6, wherein, The filtering of the laser through the first F-P etalon (11) and the second F-P etalon (12) comprises: filtering and outputting the wavelength at the transmission peak position in the laser based on the different maximum transmission peak values of the first F-P etalon (11) and the second F-P etalon (12) at different times, to obtain a single wavelength signal. The temperature of the first F-P etalon (11) and the second F-P etalon (12) is changed by changing the injection current of the third temperature control carrier (4) and the second temperature control carrier (3), so that the maximum transmission peak of the first F-P etalon (11) and the second F-P etalon (12) is moved.

9. The method of claim 7, wherein, Further comprising: The phase of the laser in the resonant cavity is changed by changing the injection current of the first temperature control carrier (2), so that the temperature of the reflection crystal (13) is changed.

10. The method of claim 7, wherein, The other part of the laser is outputted through the modulation area (9), which comprises: A current signal is applied to the modulation area (9), and the current signal is a high-level signal and a low-level signal alternately transformed at a preset interval; When the current signal is high, the modulation area (9) amplifies the laser; When the current signal is low, the modulation area (9) absorbs the laser.

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