On-chip etalon, wavelength locker and tunable laser

Abstract

The invention discloses an on-chip etalon, which comprises an etalon input waveguide, a one-to-two light beam splitter, a Mach-Zehnder interferometer and a two-in four-out light mixer, and two interference arms of the Mach-Zehnder interferometer are spirally wound with each other. The invention also discloses a wavelength locker, which comprises a wavelength locker input waveguide, an on-chip etalon, four on-chip detectors and four on-chip waveguide structures in one-to-one correspondence with the outputs of the on-chip etalon, and the four on-chip detectors convert corresponding input optical signals into electric signals in equal proportion. And the output in a differential orthogonal form is arranged in a pairwise corresponding manner. The on-chip etalon has the advantages of simple structure, low reflection and large bandwidth; the wavelength locker realizes passive wavelength locking in a large wavelength range, and is low in power consumption and high in reliability.

Description

Technical Field

[0001] The invention relates to an on-chip etalon, a wavelength locker and a tunable laser, in particular to an etalon and a wavelength locker integrated on a silicon-based optical chip and a tunable laser composed of the etalon and the wavelength locker. Background Art

[0002] At present, the wavelength lockers used in the industry for tunable lasers and other fields are mainly composed of quartz etalons and discrete photodetectors. Generally, the wavelength is locked near the median of the etalon transmission spectrum, corresponding to the maximum slope point, and the laser wavelength is adjusted in real time by monitoring the change of transmission power. The quartz etalon has a small thermo-optic coefficient and high stability, but the wavelength locker formed by it is bulky and not conducive to integration; according to application requirements, the length of the etalon needs to be precisely controlled, and the production yield is low; the transmission spectrum of the etalon will change with external environmental factors such as temperature and stress. During actual packaging, it is necessary to adjust and confirm the initial state of the etalon according to the working environment, which increases the complexity; in addition, the reflected light of the etalon will enter the laser and affect the performance of the laser. Generally, it is necessary to add an optical isolator in front of the etalon and rotate the etalon by a certain angle to reduce this effect.

[0003] On-chip wavelength lockers can greatly improve the integration of the system. On-chip wavelength lockers are generally composed of an etalon composed of waveguide interferometer devices and an integrated detector, among which microrings and Mach-Zehnder interferometers are the main choices for etalons.

[0004] Similar to quartz standards, due to the processing errors of the devices and the different working environments, the initial state of the transmission spectrum of a single microring and Mach-Zehnder interferometer is also uncertain. Generally, the wavelength to be locked is locked to the center of the transmission spectrum by changing the refractive index of the waveguide through a heater, which increases the power consumption of the system and the complexity of subsequent calibration parameters. The long-term stability of the heater is also a problem. In some applications, the on-chip wavelength locker will be affected by the ambient temperature and on-chip thermal crosstalk. In some applications, the on-chip wavelength locker will be affected by water vapor in the environment, etc., which will change the state of the wavelength locker and cause wavelength drift.

[0005] In addition, whether it is a quartz etalon or an on-chip integrated waveguide etalon, its free spectrum range is not constant within a larger wavelength range. However, the specific ITU-T grid used in communications is fixed. When there is no external adjustment mechanism to change the transmission characteristics of the etalon, some ITU-T grid wavelengths to be locked will fall to the top or valley of the transmission spectrum, resulting in invalid locking. Summary of the invention

[0006] The first objective of the present invention is to provide an on-chip etalon, which is based on a waveguide-type Mach-Zehnder interferometer and has the advantages of high integration and low reflection.

[0007] The technical solutions adopted are as follows: An on-chip etalon comprises an etalon input waveguide, a one-to-two optical beam splitter, a Mach-Zehnder interferometer and a two-input four-output optical mixer. The etalon input waveguide enters the one-to-two optical beam splitter, two outputs of the one-to-two optical beam splitter are respectively connected to the input ends of two interference arms of the Mach-Zehnder interferometer through connecting waveguides, the output ends of the two interference arms of the Mach-Zehnder interferometer are respectively connected to the two input ends of the two-input four-output optical mixer through connecting waveguides, and the four outputs of the two-input four-output optical mixer are the outputs of the on-chip etalon; the two interference arms of the Mach-Zehnder interferometer are spirally wound with each other.

[0008] The on-chip etalon of the present invention has a structure in which two interference arms are spirally wound together, so that the size of the entire device is very small, and the two interference arms can sense consistent external quantities and changes in their gradients.

[0009] The second purpose of the present invention is to provide a wavelength locker whose outputs are orthogonal to each other. By selecting a certain output as a reference value of the wavelength to be locked, the process of actively tuning the initial state of the wavelength locker can be reduced, and passive wavelength locking in a large wavelength range can be achieved with low power consumption and high reliability.

[0010] The technical solutions adopted are as follows: A wavelength locker comprises a wavelength locker input waveguide, an on-chip etalon, four on-chip detectors and four on-chip waveguide structures corresponding to the outputs of the on-chip etalon. The wavelength locker input waveguide is connected to the etalon input waveguide of the on-chip etalon. The four outputs of the on-chip etalon are connected to the four on-chip waveguide structures one by one. The other ends of the four on-chip waveguide structures are connected to the four on-chip detectors one by one. The four on-chip detectors convert the corresponding input optical signals into proportional electrical signals, and differential orthogonal outputs are set in pairs.

[0011] The third objective of the present invention is to provide a tunable laser, wherein one beam of the tunable laser enters a wavelength locker for wavelength monitoring.

[0012] The technical solutions adopted are as follows: A tunable laser comprises a gain chip, a filter chip, an end coupler, a waveguide type optical splitter, a filter device, a wavelength locker and an edge coupler. The gain chip and the filter chip are coupled through an end coupler. The waveguide type spectrometer, filter device, wavelength locker and edge coupler are all on the filter chip. The front and back sides of the gain chip are the front reflection surface of the gain chip and the rear reflection surface of the gain chip respectively. Wherein, the front end reflective surface of the gain chip and the edge coupler form two output ends of the tunable laser; The gain chip, the front-end reflection surface of the gain chip, the rear-end reflection surface of the gain chip, the end coupler, the waveguide type optical splitter and the filter device constitute the main cavity of the tunable laser; The light in the laser cavity passes through a waveguide type spectrometer and an edge coupler to realize on-chip light output of the filter chip; a part of the light in the laser cavity passes through the waveguide type spectrometer to be split to a wavelength locker for wavelength locking of the laser.

[0013] In a further preferred embodiment of the technical solution of the present invention, a heater is provided on the filter device to achieve tuning of the wavelength of the tunable laser.

[0014] In a further preferred embodiment of the technical solution of the present invention, the filter device is a microring filter, a Mach-Zehnder interferometer filter, a grating filter, a Fabry-Perot interferometer filter or a combination thereof. The filter device plays the role of filtering and feeding back light into the laser cavity.

[0015] In a further preferred embodiment of the technical solution of the present invention, the edge coupler is a large mode spot edge coupler or a small mode spot edge coupler.

[0016] In a further preferred embodiment of the technical solution of the present invention, the waveguide type optical splitter device is a directional coupler, an adiabatic directional coupler or a broadband directional coupler.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The on-chip etalon of the present invention is a waveguide device based on a Mach-Zehnder interferometer structure, and has the characteristics of simple structure, low reflection and large bandwidth; the two interference arms of the etalon adopt a waveguide structure that is spirally wound with each other, and the device size is small and the integration is high; the two interference arms can sense consistent external factors and changes in their gradients, and the device has high stability; the design can realize functions such as non-thermal sensitivity, water vapor resistance, and large manufacturing process tolerance.

[0018] 2. The wavelength locker of the present invention is mainly composed of an etalon and an on-chip photodetector. The on-chip photodetector can be set to a differential form to increase sensitivity. The differential outputs of the wavelength locker are orthogonal. By selecting a certain output as a reference value for the wavelength to be locked, the process of actively tuning the initial state of the wavelength locker can be reduced, and passive wavelength locking in a large wavelength range can be achieved with low power consumption and high reliability.

[0019] 3. The tunable laser of the present invention splits one beam into a wavelength locker to monitor the wavelength. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of an on-chip etalon 1 of the present invention; Figure 2 It is a schematic diagram of the structure of a waveguide type 90 degree mixer; Figure 3 is a schematic diagram of a wavelength locker according to an embodiment of the present invention; Figure 4 yes Figure 3 A schematic diagram of the spectral response of output signals 304a, 304b of one embodiment of a wavelength locker; Figure 5 is a schematic diagram of a tunable laser according to an embodiment of the present invention; Figure 6 is a flow chart of a method for wavelength calibration, locking and tuning of a tunable laser according to an embodiment of the present invention; Among them, 1 is an on-chip etalon, 101 is an etalon input waveguide, 102 is a one-to-two optical beam splitter, 103a is a first connecting waveguide, 103b is a second connecting waveguide, 104 is a Mach-Zehnder interferometer, 104a is a first interferometer arm, 104b is a second interferometer arm, 105a is a third connecting waveguide, 105b is a fourth connecting waveguide, 106 is a two-input and four-output optical mixer, and 107 is the output of the on-chip etalon. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the following Figure 1-Figure 6 The present invention is further described in detail with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] like Figure 1 As shown, this embodiment is an on-chip etalon 1, and its overall working principle is a Mach-Zehnder interferometer: it includes an etalon input waveguide 101, a one-to-two optical beam splitter 102, a first connecting waveguide 103a, a second connecting waveguide 103b, a Mach-Zehnder interferometer 104, a third connecting waveguide 105a, a fourth connecting waveguide 105b, and a two-input and four-output optical mixer 106. The two interference arms of the Mach-Zehnder interferometer 104 are respectively: a first interference arm 104a and a second interference arm 104b.

[0023] The standard tool input waveguide 101 enters the one-to-two optical beam splitter 102, and the two outputs of the one-to-two optical beam splitter 102 are connected to the two interference arms of the Mach-Zehnder interferometer 104 through the first connecting waveguide 103a and the second connecting waveguide 103b respectively: the input end of the first connecting waveguide 103a is connected to an output end of the one-to-two optical beam splitter 102, and the output end of the first connecting waveguide 103a is connected to the input end of the first interference arm 104a of the Mach-Zehnder interferometer 104; the input end of the second connecting waveguide 103b is connected to the other output end of the one-to-two optical beam splitter 102, and the output end of the second connecting waveguide 103b is connected to the input end of the second interference arm 104b of the Mach-Zehnder interferometer 104.

[0024] The output ends of the two interference arms of the Mach-Zehnder interferometer 104 are connected to the two input ends of the two-input and four-output optical mixer 106 through connecting waveguides: the output end of the first interference arm 104a is connected to the input end of the third connecting waveguide 105a, and the output end of the second interference arm 104b is connected to the input end of the fourth connecting waveguide 105b. In this embodiment, the two interference arms of the Mach-Zehnder interferometer 104 are spiral structures, and the two are intertwined and entangled with each other.

[0025] The output end of the third connecting waveguide 105 a is connected to one input end of the 2-input and 4-output optical mixer 106 , and the output end of the fourth connecting waveguide 105 b is connected to the other input end of the 2-input and 4-output optical mixer 106 .

[0026] In this embodiment, the two-input four-output optical mixer 106 is a two-input four-output 90-degree optical mixer; 107a, 107b, 107c, 107d are outputs of the on-chip etalon 1, which are respectively connected to the four output ports of the two-input four-output optical mixer 106.

[0027] In this embodiment, the on-chip etalon 1 is based on a waveguide-type Mach-Zehnder interferometer, which has the advantages of high integration and low reflection; the mutually spirally wound structure of the two interference arms of the Mach-Zehnder interferometer 104 makes the size of the entire device very small, and the two interference arms can sense consistent external quantities and changes in their gradients.

[0028] The following are Figure 1 Two embodiments of the etalon are described. Example 1

[0029] The entire on-chip etalon device is based on SiN material, which can achieve stable operation in a non-airtight working environment when water vapor invades. The etalon input waveguide 101 is a single-mode waveguide, and the one-to-two optical beam splitter 102 is a 1X2 multimode interference coupler to achieve power sharing in the 100nm wavelength range. The first connecting waveguide 103a and the second connecting waveguide 103b can be a single-mode waveguide or a tapered waveguide, or each is composed of a single-mode waveguide + a tapered waveguide. The first interference arm 104a and the second interference arm 104b are waveguides with slightly different widths and lengths, satisfying the following conditions: (1) (2) Wherein, n1 and n2 are the refractive indices of the first interferometer arm 104a and the second interferometer arm 104b respectively; L1 and L2 are the lengths of the first interferometer arm 104a and the second interferometer arm 104b respectively; dn_clad is the change of the cladding refractive index of the device caused by water vapor intrusion; dn1 and dn2 are the changes of the waveguide refractive index caused by the change of the cladding refractive index of the first interferometer arm 104a and the second interferometer arm 104b respectively, dn1 and dn2 are different with different waveguide parameters, but when the material, structural parameters, etc. of the waveguide are determined, this is basically a constant corresponding to a specific waveguide; FSR is the free spectral range of the etalon; c is the speed of light in a vacuum, which is a constant.

[0030] In this embodiment, the two interference arms of the on-chip etalon, the first interference arm 104a and the second interference arm 104b, are set as above to compensate for the drift of the waveguide refractive index and thus the wavelength caused by the cladding absorbing water vapor.

[0031] 105a and 105b can be single-mode waveguides or tapered waveguides, or each of them is composed of single-mode waveguides + tapered waveguides. The two-input and four-output optical mixer 106 is a 2X4 multimode interference coupler, which realizes the 90-degree mixer function in the wavelength range of 100nm; 107a, 107b, 107c, and 107d are single-mode waveguides, which are connected to other devices on the chip, such as detectors.

[0032] In this embodiment, the refractive index of the SiN material is low, so that the reflection of the entire on-chip etalon 1 is low; the thermal temperature coefficient of the SiN material is low, and the on-chip etalon 1 can simultaneously achieve low temperature sensitivity and resistance to water vapor intrusion; the entire on-chip etalon 1 has no devices such as heaters, and the fully passive waveguide structure has high stability and long-term stability. Example 2

[0033] The entire on-chip etalon device is based on Si material to achieve non-thermal sensitive functions. The etalon input waveguide 101 is a single-mode waveguide, the one-to-two optical beam splitter 102 is an adiabatic directional coupler or a broadband directional coupler, and the power distribution in the 100nm wavelength range is achieved according to the loss of the first interference arm 104a and the second interference arm 104b. The first connecting waveguide 103a and the second connecting waveguide 103b are single-mode waveguides and tapered waveguides, and the first interference arm 104a and the second interference arm 104b are waveguides with slightly different structures and lengths, which can be different in width or different in waveguide shape such as strip waveguide and ridge waveguide, and meet the following conditions: (2) (3) Where dT is the temperature change, including the overall ambient temperature change and the local temperature change on the chip.

[0034] The purpose of setting the two interference arms of the on-chip etalon in this embodiment, the first interference arm 104a and the second interference arm 104b as above is to compensate for the drift of the waveguide refractive index and thus the wavelength caused by temperature changes.

[0035] 105a and 105b are single-mode waveguides and tapered waveguides, and the two-input and four-output optical mixer 106 is a waveguide type 90-degree mixer, which realizes the 90-degree mixer function in the wavelength range of 100nm. One structure thereof is as follows: Figure 2 As shown, the specific structure is: 201 and 202 are input waveguides, connected to 105a and 105b respectively; 203a, 203b, 204a, and 204b are output waveguides, connected to 107a, 107b, 107c, and 107d respectively; 205, 206, 207, and 208 are identical adiabatic couplers with a splitting ratio of 0.5; 209, 210, 211, and 212 are 90-degree curved waveguides with the same width and the same radius of curvature, with lengths of La, Lb, Lc, and Ld respectively, and La=Lb, Lc=Ld+, where is the center wavelength and n is the waveguide refractive index.

[0036] In this embodiment, 107a, 107b, 107c, and 107d are single-mode waveguides, which are connected to other devices on the chip, such as detectors.

[0037] In the present embodiment, the entire on-chip etalon device is a waveguide type device without a multimode interference coupler, so that the reflection of the entire etalon is low; the structure in which the interference arms of the on-chip etalon are spirally wound around each other enables the two interference arms to sense consistent external quantities and changes in their gradients, and therefore has the ability to compensate for on-chip thermal crosstalk, thereby realizing a non-thermal sensitive etalon; the entire etalon has no devices such as heaters, and the fully passive waveguide structure has high stability and long-term stability.

[0038] like Figure 3 As shown, a wavelength locker 3 involved in an embodiment of the present invention.

[0039] A wavelength locker 3 includes a locker input waveguide 301, an on-chip etalon 1, four on-chip waveguide structures and four on-chip detectors. The four outputs of the on-chip etalon 1 are connected to the four on-chip waveguide structures one by one, and the other ends of the four on-chip waveguide structures are connected to the four on-chip detectors one by one. The four on-chip detectors convert the corresponding input optical signals into proportional electrical signals, and differential outputs 304 are set in pairs.

[0040] like Figure 3 As shown, the specific structure is as follows: The four on-chip detectors are: a first on-chip detector 303a, a second on-chip detector 303b, a third on-chip detector 303c, and a fourth on-chip detector 303d, and the four on-chip waveguide structures are: a first on-chip waveguide structure 302a, a second on-chip waveguide structure 302b, a third on-chip waveguide structure 302c, and a fourth on-chip waveguide structure 302d.

[0041] The locker input waveguide 301 is connected to the etalon input waveguide 101 of the on-chip etalon 1; one ends of the first on-chip waveguide structure 302a, the second on-chip waveguide structure 302b, the third on-chip waveguide structure 302c, and the fourth on-chip waveguide structure 302d are respectively connected to the four output ports 107a, 107b, 107c, and 107d of the on-chip etalon 1 in a one-to-one correspondence; the other ends of the first on-chip waveguide structure 302a, the second on-chip waveguide structure 302b, the third on-chip waveguide structure 302c, and the fourth on-chip waveguide structure 302d are connected to the first on-chip detector 303a, the second on-chip detector 303b, the third on-chip detector 303c, and the fourth on-chip detector 303d in a one-to-one correspondence.

[0042] The first on-chip waveguide structure 302a and the second on-chip waveguide structure 302b are complementary signals, the third on-chip waveguide structure 302c and the fourth on-chip waveguide structure 302d are complementary signals, and the four on-chip detectors 303a, 303b, 303c, and 303d convert the corresponding input optical signals into proportional electrical signals, and the four on-chip detectors 303a, 303b, 303c, and 303d can be composed of materials such as germanium silicon or indium phosphide.

[0043] 304a and 304b are output electrical differential signals, wherein 304a is the differential signal of 303a and 303b, which can be directly obtained by setting the detectors 303a and 303b to a differential form, and 304b is the differential signal of 303c and 303d, which can be directly obtained by setting the detectors 303c and 303d to a differential form.

[0044] like Figure 4 As shown, the spectral response of the output signals 304a and 304b of an embodiment of the wavelength locker 3. In the range of 184THz to 197THz, there are certain differences in the maximum and minimum values ​​of the output curves of 304a and 304b; this difference is the smallest near the center frequency (190.5THz) and reaches the maximum near the two end frequencies (184.1THz, 197THz). However, in the 184THz to 197THz band, this difference is <2dB; the phase difference between 304a and 304b is around 90 degrees in the entire band, that is, each wavelength to be locked can select one of 304a or 304b, so that it falls near the median point of the corresponding curve, avoiding the situation where some wavelength points fall into the peak point or valley point of the curve when a single curve is used.

[0045] like Figure 5 As shown, an embodiment of the present invention relates to a tunable laser 5.

[0046] A tunable laser 5 includes a gain chip 501, a filter chip 502, an end coupler 505, a waveguide type optical splitter 506, a filter device 507, a wavelength locker 3 and an edge coupler 508.

[0047] In this embodiment, the front end reflection surface 503 of the gain chip can be designed as a high reflection surface or a low reflection surface according to the light output requirements; the rear end reflection surface 504 of the chip is coated with an anti-reflection film; the end face coupler 505 has a typical single-ended loss of <2dB, thereby achieving efficient coupling between the gain chip 501 and the filter chip 502.

[0048] The waveguide type spectrometer 506, filter device 507, wavelength locker 3 and edge coupler 508 are all on the filter chip 502. The waveguide type spectrometer 506 can be implemented using low-loss and low-reflection structures such as conventional directional couplers, adiabatic directional couplers, and broadband directional couplers.

[0049] The filter device 507 can be implemented using a conventional micro-ring filter, a Mach-Zehnder interferometer filter, a grating filter, a Fabry-Perot interferometer filter or a combination thereof, which plays a role in filtering and feeding light back into the laser cavity in this embodiment. In order to adjust the wavelength of the tunable laser 5, a heater is provided on the filter device 507 to achieve tuning of the filter wavelength. The heater is a product known to those skilled in the art.

[0050] The gain chip 501, the front-end reflection surface 503 of the gain chip, the rear-end reflection surface 504 of the gain chip, the end coupler 505, the waveguide type optical splitter 506 and the filter device 507 constitute the main cavity of the tunable laser; The on-chip wavelength locker 3 adopts the aforementioned Figure 3The on-chip wavelength locker 3 shown has the characteristics of low reflection and large bandwidth. In the tunable laser 5 of this embodiment, a part of the light in the laser cavity is split through the waveguide type optical splitter 506 to the wavelength locker 3 for wavelength locking of the laser.

[0051] In the tunable laser 5 of this embodiment, the light in the laser cavity is emitted on the filter chip through the waveguide type optical splitter 506 and the edge coupler 508. The edge coupler 508 can be designed as a large mode spot edge coupler directly end-face coupled with an ordinary single-mode optical fiber, or can be designed as a small mode spot edge coupler for spatial light coupling.

[0052] like Figure 6 As shown, an embodiment of the present invention relates to a method for wavelength calibration, locking and tuning of a tunable laser 5.

[0053] A method for wavelength calibration, locking and tuning of a tunable laser 5 includes the following steps: steps 601, 602, 603, 604, and 605, wherein steps 601, 602, and 603 are wavelength calibration processes, and steps 604 and 605 are laser wavelength locking and tuning processes.

[0054] Step 601, adjusting the filter in the tunable laser 5 to adjust the tunable laser 5 to ±0.1 GHz around the wavelength to be locked; Step 602, read the two branches of the on-chip wavelength locker 3, and select the branch where the signal falls near the median of the curve; Step 603: record and store the signal value of the corresponding output branch; Step 604, read the signal value of the on-chip wavelength locker 3 in real time, and compare it with the signal value of the storage branch; Step 605: According to the difference between the two in step 604, adjust the parameters of the filter in the tunable laser 5 so that the difference between the signal value of the output branch corresponding to the wavelength to be locked and the stored value is less than 5%.

[0055] In this embodiment, step 601 is specifically to monitor the wavelength by a device such as a wavelength meter; specifically, to adjust the filter in the tunable laser 5 and read the wavelength meter so that the wavelength of the tunable laser 5 differs from the wavelength to be locked by ±0.1 GHz.

[0056] In this embodiment, step 602 specifically includes reading two outputs of the on-chip wavelength locker 3, such as Figure 3 The outputs 304a and 304b of the embodiment are selected, and the branch whose output signal value is close to the median value is selected as the wavelength locker branch of the wavelength to be locked, such as Figure 3 In 304a and 304b, a branch with a signal value close to 0 can be selected. The purpose of this step is to select a point with greater sensitivity for each wavelength to be locked.

[0057] In this embodiment, step 603 specifically records the signal value of the wavelength to be locked, and this value will be used as a reference value of the wavelength signal of the subsequent laser. During the operation of the laser, factors such as noise interference from the external environment will cause the drift of the laser working state, such as the change of the laser wavelength. It is necessary to monitor the output of the wavelength locker in real time and provide feedback to tune the wavelength.

[0058] In this embodiment, step 604 specifically includes reading the output signal value of the laser wavelength locker in real time and comparing it with the stored standard value of the calibration process.

[0059] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An on-chip etalon, characterized in that: It includes an etalon input waveguide (101), a one-to-two optical beam splitter (102), a Mach-Zehnder interferometer (104) and a two-input four-output optical mixer (106). The etalon input waveguide (101) enters a one-to-two optical beam splitter (102); two outputs of the one-to-two optical beam splitter (102) are respectively connected to the input ends of two interference arms of a Mach-Zehnder interferometer (104) through connecting waveguides; the output ends of the two interference arms of the Mach-Zehnder interferometer (104) are respectively connected to the two input ends of a two-input four-output optical mixer (106) through connecting waveguides; and the four outputs of the two-input four-output optical mixer (106) are the outputs of the on-chip etalon (1); the two interference arms of the Mach-Zehnder interferometer (104) are spirally wound around each other.

2. A wavelength locker, manufactured using the on-chip etalon according to claim 1, characterized in that: The invention comprises a wavelength locker input waveguide (301), an on-chip etalon (1), four on-chip detectors, and four on-chip waveguide structures corresponding one to one with the outputs of the on-chip etalon (1). The wavelength locker input waveguide (301) is connected to the etalon input waveguide (101) of the on-chip etalon (1), and the four outputs of the on-chip etalon (1) are connected to the four on-chip waveguide structures one by one. The other ends of the four on-chip waveguide structures are connected to the four on-chip detectors one by one. The four on-chip detectors convert the corresponding input optical signals into electrical signals of equal proportion, and the differential orthogonal outputs are arranged in pairs.

3. A tunable laser, manufactured using the wavelength locker according to claim 2 and the on-chip etalon according to claim 1, characterized in that: It comprises a gain chip (501), a filter chip (502), an end coupler (505), a waveguide type optical splitter (506), a filter device (507), a wavelength locker (3) and an edge coupler (508), The gain chip (501) and the filter chip (502) are coupled via an end face coupler (505); the waveguide type optical splitter (506), the filter device (507), the wavelength locker (3) and the edge coupler (508) are all on the filter chip (502); the front and back sides of the gain chip (501) are respectively a gain chip front end reflection surface (503) and a gain chip rear end reflection surface (504); The front end reflection surface (503) of the gain chip and the edge coupler (508) form two output ends of the tunable laser; The gain chip (501), the front-end reflection surface (503) of the gain chip, the rear-end reflection surface (504) of the gain chip, the end-face coupler (505), the waveguide-type optical splitter (506) and the filter device (507) constitute the main cavity of the tunable laser; The light in the laser cavity passes through a waveguide type optical splitter (506) and an edge coupler (508) to realize on-chip light output of a filter chip; a portion of the light in the laser cavity passes through the waveguide type optical splitter (506) and is split to a wavelength locker (3) for wavelength locking of the laser.

4. The tunable laser according to claim 3, characterized in that: A heater is provided on the filter element (507).

5. The tunable laser according to claim 3, characterized in that: The filter element (507) is a micro-ring filter, a Mach-Zehnder interferometer filter, a grating filter, a Fabry-Perot interferometer filter or a combination thereof.

6. The tunable laser according to claim 3, characterized in that: The edge coupler (508) is a large mode spot edge coupler or a small mode spot edge coupler.

7. The tunable laser according to claim 3, characterized in that: The waveguide type optical splitter (506) is a directional coupler, an adiabatic directional coupler or a broadband directional coupler.

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