CN-122018097-A - Temperature insensitive silicon-based hybrid full-integrated active optical frequency laser regeneration relay chip, optical frequency transmission system and method

CN122018097ACN 122018097 ACN122018097 ACN 122018097ACN-122018097-A

Abstract

A temperature insensitive silicon-based hybrid integrated active optical frequency laser regeneration relay chip is suitable for a photon integrated optical frequency cascade transmission system. The chip can perform on-chip regenerative amplification on the received upper-level optical signal and output an optical frequency signal with stable phase to the lower level. The invention uses the low-loss passive silicon-based waveguide as the extremely low, and can effectively inhibit out-of-band phase noise caused by temperature change and improve the environmental adaptability of the chip by strictly length matching of the out-of-band waveguide path in the chip. Meanwhile, by means of advanced processes such as micro transfer printing and the like, the high-efficiency on-chip frequency shifter and the polarization controller which are realized based on high-electro-optical coefficient materials such as film lithium niobate and the like are subjected to heterogeneous mixing integration, so that the on-chip optical frequency laser regeneration relay chip with complete functions is constructed. The chip has the advantages of compact structure, low power consumption, strong environmental adaptability and the like, and is suitable for the construction of the next generation of miniaturized optical frequency transmission network.

Inventors

HU LIANG
QIU ZIANG
Zhong Hanzhao
XU YAOHUI
WU GUILING
CHEN JIANPING

Assignees

上海交通大学

Dates

Publication Date: 20260512
Application Date: 20260210

Claims (9)

1. The temperature insensitive silicon-based hybrid full-integrated active optical frequency laser regeneration relay chip is characterized by comprising a silicon-based passive waveguide layer and a thin film lithium niobate active waveguide layer which are stacked, wherein the silicon-based passive waveguide layer and the thin film lithium niobate active waveguide layer realize optical signal coupling through a plurality of interlayer couplers which are vertically arranged; The silicon-based passive waveguide layer integrates a first distributed feedback laser gain chip (0), a first self-injection locking external cavity (1), a first directional coupler (2), a second directional coupler (3), a third directional coupler (4), a fourth directional coupler (5), a first end face coupler (6), a second end face coupler (7), a fifth directional coupler (8), a first multimode interferometer (9), a third end face coupler (10), a sixth directional coupler (11), a seventh directional coupler (12), a second multimode interferometer (13), a fourth end face coupler (14), a third multimode interferometer (15), a fourth multimode interferometer (16), a fifth multimode interferometer (17), a fifth end face coupler (18), a sixth end face coupler (19), a sixth multimode interferometer (20), a seventh multimode interferometer (21), an eighth multimode interferometer (22), a seventh end face coupler (23) and an eighth end face coupler (24); the thin-film lithium niobate active waveguide layer is integrated with a first frequency shifter (26), a second frequency shifter (29), a first polarization controller (32) and a third frequency shifter (33); The laser output port of the first distributed feedback laser gain chip (0) is optically connected with the input port of the first self-injection locking outer cavity (1), the output port of the first self-injection locking outer cavity (1) is optically connected with the first port of the first frequency shifter (26) through a first interlayer coupler (25), and the second port of the first frequency shifter (26) is optically connected with the combining port of the first directional coupler (2) through a second interlayer coupler (27); the first shunt port of the first directional coupler (2) is optically connected with the combining port of the second directional coupler (3), and the second shunt port of the first directional coupler (2) is optically connected with the combining port of the sixth directional coupler (11); The first shunt port of the second directional coupler (3) is optically connected with the combining port of the third directional coupler (4), and the second shunt port of the second directional coupler (3) is connected with the combining port of the third multimode interferometer (15); The first branch port and the second branch port of the third multimode interferometer (15) are respectively connected with the second branch port of the fifth multimode interferometer (17) and the first branch port of the fourth multimode interferometer (16); The input port of the fifth multimode interferometer (17) is connected with an external photoelectric detector for bidirectional optical frequency comparison beat frequency test, the combining port of the fourth multimode interferometer (16) is connected with the output port of the sixth end surface coupler (19), and the input port of the sixth end surface coupler (19) is connected with an external short fiber or an external frequency shifter for bidirectional optical frequency comparison test; The first shunt port of the third fixed coupler (4) is connected with the second shunt port of the second multimode interferometer (13), and the second shunt port of the third fixed coupler (4) is connected with the first shunt port of the fourth directional coupler (5); The combining port of the fourth directional coupler (5) is connected with the first port of the second frequency shifter (29) through a third interlayer coupler (28), the second port of the second frequency shifter (29) is connected with the output port of the first end face coupler (6) through a fourth interlayer coupler (30), the second branch port of the fourth directional coupler (5) is connected with the first branch port of the second multimode interferometer (13), the input port of the first end face coupler (6) is connected with an external transmission link for transmitting optical frequency signals to a next stage link, the combining port of the second multimode interferometer (13) is connected with the output port of the fourth end face coupler (14), and the input port of the fourth end face coupler (14) is connected with an external photoelectric detector for locking the next stage link The first shunt port of the sixth directional coupler (11) is connected with the combining port of the sixth multimode interferometer (20), and the second shunt port of the sixth directional coupler (11) is connected with the combining port of the seventh directional coupler (12); the first branch port and the second branch port of the sixth multimode interferometer (20) are respectively connected with the second branch port of the seventh multimode interferometer (21) and the first branch port of the eighth multimode interferometer (22), the first branch port and the combining port of the seventh multimode interferometer (21) are respectively connected with the second branch port of the eighth multimode interferometer (22) and the output port of the seventh end face coupler (23), the input port of the seventh end face coupler (23) is connected with an external short fiber or an external frequency shifter for bidirectional optical frequency comparison test, the combining port of the eighth multimode interferometer (22) is connected with the output port of the eighth end face coupler (24), and the input port of the eighth end face coupler (24) is connected with an external photoelectric detector for bidirectional optical frequency comparison test; The first shunt port and the second shunt port of the seventh directional coupler (12) are respectively connected with the first shunt port of the fifth directional coupler (8) and the second shunt port of the first multimode interferometer (9), the first shunt port and the combining port of the first multimode interferometer (9) are respectively connected with the second shunt port of the fifth directional coupler (8) and the output port of the third directional coupler (10), and the input port of the third directional coupler (10) is connected with an external photoelectric detector for realizing the locking of on-chip regeneration laser; The combining end of the fifth directional coupler (8) is connected with the first port of the third frequency shifter (33) through a sixth interlayer coupler (34), the second port of the third frequency shifter (33) is connected with the first port of the first polarization controller (32), the second port of the first polarization controller (32) is connected with the output port of the second end face coupler (7) through a fifth interlayer coupler (31), and the input port of the second end face coupler (7) is connected with an external transmission link and used for receiving optical frequency signals transmitted by the previous stage.
2. The temperature-insensitive silicon-based hybrid fully integrated active optical frequency laser regeneration relay chip of claim 1, wherein the silicon-based passive waveguide layer is based on any one of a silicon-on-insulator, a silicon nitride or a silicon dioxide platform, the thin-film lithium niobate active waveguide layer is based on a lithium niobate platform on an insulator, and heterogeneous hybrid integration is achieved by a micro transfer printing process between the silicon-based passive waveguide layer and the thin-film lithium niobate active waveguide layer.
3. The temperature-insensitive silicon-based hybrid fully integrated active optical frequency laser regeneration relay chip of claim 1, wherein the plurality of specific waveguide paths in the silicon-based passive waveguide layer satisfy a preset length matching relationship to suppress non-common mode phase noise caused by temperature variation, the length matching relationship comprising: The waveguide length between the seventh directional coupler (12) and the first multimode interferometer (9) is equal to the sum of the waveguide length between the fifth directional coupler (8) and the first multimode interferometer (9), the waveguide length between the seventh directional coupler (12) and the fifth directional coupler (8) is equal to the sum of the waveguide length between the third directional coupler (4) and the second multimode interferometer (13), the waveguide length between the fourth directional coupler (5) and the second multimode interferometer (13) is equal to the sum of the waveguide length between the third directional coupler (4) and the fourth multimode interferometer (5), the waveguide length between the second directional coupler (3) and the fourth directional coupler (5) is equal to the sum of the waveguide length between the second directional coupler (3) and the third multimode interferometer (15), the waveguide length between the fourth directional coupler (4) and the fourth multimode interferometer (13) is equal to the sum of the waveguide length between the fourth multimode interferometer (16) and the fifth multimode interferometer (5), and the waveguide length between the fourth directional coupler (16) and the fourth multimode interferometer (17) is equal to the sum of the waveguide length between the fourth multimode interferometer (17) and the fifth multimode interferometer (15) and the waveguide length between the fourth multimode interferometer (17 and the fifth multimode interferometer (15) and the waveguide (15) is equal to the sum of the waveguide lengths between the fourth multimode interferometer (17 and the fourth multimode interferometer (17) and the fourth multimode interferometer (5) The waveguide length between the sixth directional coupler (11) and the fifth directional coupler (8), the waveguide length between the seventh multimode interferometer (21) and the eighth multimode interferometer (22) being equal to the sum of the waveguide length between the sixth multimode interferometer (20) and the seventh multimode interferometer (21) and the waveguide length between the sixth multimode interferometer (20) and the eighth multimode interferometer (22).
4. The temperature-insensitive silicon-based hybrid fully integrated active optical frequency laser regeneration relay chip of claim 1, wherein the first frequency shifter (26), the second frequency shifter (29) and the third frequency shifter (33) are electro-optic phase modulators based on thin film lithium niobate waveguides and traveling wave electrodes, and the first polarization controller (32) is an electro-optic polarization controller based on thin film lithium niobate waveguides and a multi-electrode structure.
5. The hybrid fully integrated active optical frequency laser regeneration relay chip of claim 1, wherein the first distributed feedback laser gain chip (0) is coupled to a first self-injection locked external cavity (1) on a silicon-based platform on the silicon-based passive waveguide layer by a flip-chip bonding process by external bonding to produce an on-chip narrow linewidth laser signal that can be used as an on-chip regeneration laser.
6. An optical frequency delivery system comprising at least two temperature insensitive silicon based hybrid fully integrated active optical frequency laser regeneration relay chips as defined in any one of claims 1 to 5, wherein: the first chip is used as a main end chip, and a first end surface coupler (6) of the first chip is optically connected with a second end surface coupler (7) of the second chip serving as a slave end chip through a first optical fiber link to construct a unidirectional optical frequency transmission main path; The first end face coupler (6) of the slave end chip is optically connected with a lower-level link or a terminal and is used for outputting the regenerated optical frequency signal.
7. The optical frequency delivery system of claim 6, wherein the slave chip further comprises a third photodetector (335) and a second phase locked loop (336), the third photodetector (335) being optically connected to a third end-face coupler (10) of the slave chip for detecting an optical signal from the master chip and a beat signal of the slave locally regenerated laser, the second phase locked loop (336) generating a control signal based on the beat signal, feedback controlling the first distributed feedback laser gain chip (300) and/or the first frequency shifter (326) of the slave chip to achieve frequency and phase locking of the slave regenerated laser and the received signal.
8. The optical frequency delivery system of claim 7, wherein the master-side chip further comprises a first photodetector (135) and a first phase-locked loop (136), the first photodetector (135) being optically coupled to the fourth-side coupler (114) of the master-side chip for detecting a beat signal of the return optical signal from the slave-side chip and the master-side local reference light, the first phase-locked loop (136) generating a control signal based on the beat signal and feedback controlling the second frequency shifter (129) of the master-side chip to compensate for phase noise introduced by the first optical fiber link.
9. A method of optical frequency signal cascading using the optical frequency transfer system of any one of claims 6-8, comprising: A main-side reproduction locking step of locking, in a main-side chip, the frequency and phase of the reproduction laser light generated by the first distributed feedback laser gain chip (0) to an input optical frequency signal from an upper link received via the second end-side coupler (7) by using the first frequency shifter (26) and an external phase-locked loop connected to the third end-side coupler (10); A link forward transfer and slave end regeneration step of transmitting the locked master end regeneration laser to a slave end chip through the first end face coupler (6) and a first optical fiber link, wherein in the slave end chip, the frequency and the phase of the regeneration laser generated by the slave end chip are locked to the received optical signal from the master end chip by utilizing the third frequency shifter (33) and an external phase-locked loop connected with the eleventh end face coupler (310); The method comprises a link reverse locking and noise compensation step, wherein the regenerated laser after being locked by a slave chip is transmitted back to a master chip through the second end face coupler (307) and the first optical fiber link, in the master chip, a control signal is generated according to beat signals of a return signal and local reference light by using the second frequency shifter (29) and an external phase-locked loop connected with the fourth end face coupler (114) to drive the second frequency shifter (29) so as to compensate phase noise introduced by the first optical fiber link, and the phase locking of the first optical fiber link is completed, and the stable transmission step comprises the step that the master chip continuously outputs a phase stable optical frequency signal to the slave chip through the first optical fiber link after the link reverse locking and noise compensation step is completed.

Description

Temperature insensitive silicon-based hybrid full-integrated active optical frequency laser regeneration relay chip, optical frequency transmission system and method Technical Field The invention relates to the technical field of photon integration technology and optical frequency transmission, in particular to a temperature-insensitive silicon-based hybrid full-integrated active optical frequency laser regeneration relay chip, an optical frequency transmission system and a method. Background The construction of the ultra-long distance foundation optical frequency network has important significance, and the construction of the ultra-long distance foundation optical frequency network promotes the evolution of a time-frequency synchronization system from the traditional microwave atomic clock to the high-precision optical clock, so that the application potential of the ultra-long distance foundation optical frequency network in the fields of earth crust movement monitoring, tidal effect research, gravitational wave detection and the like is expanded. In order to prolong the optical frequency transmission distance and improve the adaptability of the system to high noise links, a cascade transmission architecture based on laser regeneration relay is generated. In conventional laser regenerative relay interferometers, temperature variations can introduce out-of-band phase noise in non-common mode paths. The noise is linearly related to the temperature variation and accumulates as the number of cascade stages increases, severely degrading the long-term stability of the system. While suppression can be achieved by out-of-line phase noise detection and compensation, further increases in system power consumption and complexity, and the photon integration technology developed in recent years, see [Qiu Z, Zhou Z, Hu L, et al. Temperature-induced noise-insensitive laser repeater station for optical frequency transfer[J]. IEEE Transactions on Instrumentation and Measurement, 2025.]., provides an ideal solution to the above-mentioned problems. By integrating the micron-sized interferometer structure into the waveguide, the intrinsic delay error can be remarkably reduced, and more importantly, the on-chip waveguide path is easy to realize the precise matching of the out-of-band length, thereby being beneficial to the construction of temperature insensitive system design. However, the currently reported photonic integrated optical frequency transmission laser regeneration relay only realizes the integration of a passive silicon dioxide waveguide, key active devices (such as a laser, a frequency shifter and a polarization controller) are not miniaturized yet, see [Akatsuka T, Goh T, Imai H, et al. Optical frequency distribution using laser repeater stations with planar lightwave circuits[J]. Optics express, 2020, 28(7): 9186-9197.]., which are based on a high-performance material platform such as thin film lithium niobate, and the like, and by virtue of the excellent electro-optic effect, the high-efficiency on-chip key active devices can be realized, see [Lin Z, Lin Y, Li H, et al. High-performance polarization management devices based on thin-film lithium niobate[J]. Light: Science&Applications, 2022, 11(1): 93.]., so that the silicon-based waveguide and the functional platform such as the thin film lithium niobate are mixed and heterogeneous integrated, and the photonic integrated chip is a core technical approach for realizing a full-function integrated optical frequency transmission photonic integrated chip. Disclosure of Invention The invention aims to overcome the defects of large volume, high environmental sensitivity and low integration level of key active devices of an optical frequency laser regeneration relay system in the prior art and provides a temperature-insensitive silicon-based hybrid full-integrated active optical frequency laser regeneration relay chip architecture and a design method. The scheme structurally suppresses on-chip out-of-band phase noise introduced by temperature variations by performing a strict length matching of the out-of-band waveguide path in a silicon-based passive interferometer. Meanwhile, based on advanced hybrid integration processes such as micro transfer printing, a frequency shifter and a polarization controller realized by a thin film lithium niobate platform are subjected to heterogeneous integration with a silicon-based interferometer, so that an integrated full-function on-chip laser regeneration relay chip facing cascade optical frequency transfer is constructed. In order to achieve the above purpose, the technical solution of the present invention is as follows: the temperature insensitive silicon-based hybrid full-integrated active optical frequency laser regeneration relay chip is characterized by comprising a silicon-based passive waveguide layer and a thin film lithium niobate active waveguide layer which are stacked, wherein the silicon-based passive waveguide laye