Photonic integrated circuit and optoelectronic system comprising a photonic integrated circuit

Abstract

The invention relates to a PIC (1) comprising at least three fiber-to-chip coupling locations (2, 3, 4), an InP-based polarization handling unit, at least two optical splitters-combiners (9, 11), at least two optical receivers (5, 7) and a plurality of semiconductor-based optical waveguides. The plurality of semiconductor-based optical waveguides is configured and arranged to optically connect the first fiber-to-chip coupling location (2) with the first optical receiver (5) via the first optical splitter-combiner (9), to optically connect the second fiber-to-chip coupling location (3) with the at least two optical receivers (5, 7) via the InP-based polarization handling unit and the at least two optical splitters-combiners (9, 11), and to optically connect the third fiber-to-chip coupling location (4) with the second optical receiver (7) via the second optical splitter-combiner (11). The invention further relates to an optoelectronic system (100) comprising said PIC (1).

Description

TECHNICAL FIELD

[0001] The present invention relates to a photonic integrated circuit (PIC) which can be used for example but not limited to telecommunication applications, Light Detection and Ranging (LIDAR) or sensor applications. The present invention further relates to an optoelectronic system comprising said PIC. BACKGROUND

[0002] PICs which can be applied for example but not limited to optical communication applications, LIDAR or sensor applications are becoming more and more complex due to the increasing number of optical and / or electrical functions which are integrated on a single die, which single die preferably has the smallest possible size.

[0003] One example of an increasingly complex PIC is a PIC which can be used for coherent reception. It is known that coherent transmission involves encoding information by modulating the amplitude and phase of two optical carriers. Two polarizations, namely transverse magnetic (TM) and transverse electric (TE), are usually used to prevent the optical carriers from interfering with each other when propagating along the same optical path, for example formed by an optical fiber or an integrated optical waveguide. In order to recover the encoded information, it is necessary to separate the TM and TE modes in the received optical signal. If the optical receiver is configured as a coherent receiver or if a modulation format involving amplitude modulation is used, the optical receiver is able to separate the TM and TE modes in the received optical signal.

[0004] The most versatile technology platform for PICs, in particular for optical communication applications, uses wafers containing InP-based semiconductor materials. InP-based technology enables monolithic integration of active devices, for example optical devices which generate and / or absorb light, and passive devices, for example optical devices which are optical guides and / or optical switches, in one PIC on a single die.

[0005] It is known that most InP-based PICs are optimized for handling TE modes due to the confinement properties of quantum wells. Therefore, in the case of for example coherent reception, it is common practice to separate the TM and TE modes and then to rotate or convert the TM modes into TE modes. Polarization splitter devices are usually used to separate the TM and TE modes and polarization rotator devices are usually used to subsequently rotate or convert the TM modes into TE modes.

[0006] One drawback known for highly complex PICs, in particular PICs comprising at least one InP-based polarization splitter and one InP-based polarization rotator, is that achieving a suitable chip yield is very challenging due to the high manufacturing complexity and sensitivity of the above-mentioned components and the fact that CMOS-level process control has not yet been widely adopted for InP-based platforms. Therefore, there is a need to provide a PIC comprising an InP-based polarization splitter and an InP-based polarization rotator which enables an improved chip yield due to an improved design of the PIC. SUMMARY

[0007] It is an object of the present application to provide a PIC comprising an InP-based polarization splitter and an InP-based polarization rotator which can be used for example but not limited to telecommunication applications, LIDAR or sensor applications, which prevents or at least reduces at least one of the above-mentioned and / or other drawbacks associated with PICs known in the art comprising an InP-based polarization splitter and an InP-based polarization rotator.

[0008] It is a further object of the present application to provide an optoelectronic system which can be used for example but not limited to telecommunication applications, LIDAR or sensor applications, which comprises a PIC according to the present application.

[0009] Various aspects of the present application are set out in the accompanying independent and dependent claims. The features of the dependent claims may, of course, be combined with those of the independent claims where appropriate and not merely in the particular combinations explicitly set out or specifically made claim to in the claims. In addition, all features of the application may, of course, be replaced by other technically equivalent features.

[0010] At least one of the above-mentioned objects is achieved by a PIC comprising:

[0011] at least three fiber-to-chip coupling locations;

[0012] an InP-based polarization handling unit;

[0013] at least two optical de-multiplexers-multiplexers;

[0014] at least two optical receivers; and

[0015] a plurality of semiconductor-based optical waveguides;

[0016] wherein the plurality of semiconductor-based optical waveguides are configured and arranged to:

[0017] optically connect a first fiber-to-chip coupling location of the at least three fiber-to-chip coupling locations with a first optical receiver of the at least two optical receivers via a first optical de-multiplexer-multiplexer of the at least two optical de-multiplexer-multiplexers;

[0018] - The second fiber-to-chip coupling position of the at least three fiber-to-chip coupling positions is optically connected to the at least two optical receivers via the InP-based polarization processing unit and the at least two optical splitter-combiner; and

[0019] - The third fiber-to-chip coupling position of the at least three fiber-to-chip coupling positions is optically connected to the second optical receiver of the at least two optical receivers via the second optical splitter-combiner of the at least two optical splitter-combiner.

[0020] Embodiments of the PIC defined above according to the present invention have an improved design that can bypass the on-chip InP-based polarization processing unit and instead use off-chip polarization processing components and / or systems. The off-chip polarization processing components and / or systems can be optically connected to the PIC at a first and / or third fiber-to-chip coupling location out of at least three fiber-to-chip coupling locations. If the on-chip InP-based polarization processing unit of the PIC has non-compliant polarization processing performance, i.e., the polarization processing performance is not within the required specifications, the compatibility of the PIC according to the present invention with off-chip polarization processing components and / or systems may be advantageous. Therefore, the PIC according to the present invention does not need to be scrapped due to the non-compliant performance of the on-chip InP-based polarization processing unit, but can still be applied to modules or optoelectronic systems using off-chip polarization processing components and / or systems. Therefore, as a result of the improved PIC design according to the present invention, the improved chip enables high-volume production.

[0021] Different exemplary use cases of the PIC embodiments defined above according to the present invention are conceivable. According to a first exemplary use case, the on-chip polarization processing capability of the PIC according to the present invention can be fully utilized by transmitting optical radiation including TM and TE modes to the PIC via a second fiber-to-chip coupling location among at least three fiber-to-chip coupling locations, the second fiber-to-chip coupling location being optically connected to an on-chip InP-based polarization processing unit via a semiconductor-based optical waveguide. First, the on-chip InP-based polarization processing unit separates the TM and TE modes of the received optical radiation. Second, the on-chip InP-based polarization processing unit rotates the TM mode to obtain a converted TE mode. Subsequently, the TE mode and the converted TE mode can be guided to different optical receivers among the at least two optical receivers via a semiconductor-based optical waveguide among a plurality of semiconductor-based optical waveguides. The first exemplary use case described above represents a low-cost, low-performance, but fully on-chip polarization processing solution provided by the PIC according to the present invention.

[0022] According to a third exemplary use case of the PIC of the present invention, if the performance of the on-chip polarization splitter does not meet specifications, the polarization splitter of the on-chip InP-based polarization processing unit can be bypassed. The on-chip polarization splitter can be bypassed by transmitting optical radiation including a TM mode separated from the TE mode by an off-chip polarization splitter into the PIC via a first fiber-to-chip coupling location among at least three fiber-to-chip coupling locations, and by transmitting optical radiation including a TE mode into the PIC via a third fiber-to-chip coupling location among at least three fiber-to-chip coupling locations. The TM mode can be guided to the polarization rotator of the on-chip InP-based polarization processing unit via a first optical splitter-combiner among at least two optical splitter-combiners and a semiconductor-based optical waveguide among a plurality of semiconductor-based optical waveguides. The polarization rotator of the on-chip InP-based polarization processing unit can rotate the TM mode to obtain a converted TE mode. Subsequently, the converted TE mode can be guided to a first optical receiver among at least two optical receivers via a semiconductor-based optical waveguide among a plurality of semiconductor-based optical waveguides. The TE mode transmitted into the PIC via the third fiber-to-chip coupling location can be guided to the second optical receiver of at least two optical receivers via the second optical-optical splitter-combiner of at least two optical splitter-combiners and the semiconductor-based optical waveguide of a plurality of semiconductor-based optical waveguides. Compared with the fully on-chip polarization processing solution provided by the PIC according to the present invention, the third exemplary use case represents a more cost-effective and higher-performance hybrid polarization processing solution provided by the PIC according to the present invention.

[0023] According to a second exemplary use case of the PIC of the present invention, if the performance of the on-chip polarization splitter and the on-chip polarization rotator does not meet specifications, the on-chip InP-based polarization processing unit can be completely bypassed. In this case, polarization separation and polarization rotation are performed entirely by off-chip components and / or systems. The off-chip separated and converted TE mode can be transmitted into the PIC via a first fiber-to-chip coupling location among at least three fiber-to-chip coupling locations, and guided to a first optical receiver among at least two optical receivers via a first splitter-combiner among at least two optical splitter-combiners and a semiconductor-based optical waveguide among a plurality of semiconductor-based optical waveguides. The off-chip separated TE mode can be transmitted into the PIC via a third fiber-to-chip coupling location among at least three fiber-to-chip coupling locations, and guided to a second optical receiver among at least two optical receivers via a second optical splitter-combiner among at least two optical splitter-combiners and a semiconductor-based optical waveguide among a plurality of semiconductor-based optical waveguides. Compared to the fully on-chip and hybrid polarization processing solutions provided by the PIC according to the present invention, the second exemplary use case represents the highest cost and highest performance fully off-chip polarization processing solution provided by the PIC according to the present invention.

[0024] Those skilled in the art will understand that, depending on the specific requirements of the PIC, any suitable number of three or more fiber-to-chip coupling locations, any suitable number of one or more InP-based polarization processing units, any suitable number of two or more optical splitter-combiners, any suitable number of two or more optical receivers, and any suitable number of semiconductor-based optical waveguides can be envisioned.

[0025] In an embodiment of the PIC according to the present invention,

[0026] - The first optical receiver of the at least two optical receivers has a first optical input port;

[0027] - The second optical receiver of the at least two optical receivers has a second optical input port;

[0028] -The first optical splitter-combiner has:

[0029] • The first end, which is provided with at least a first optical interface and a second optical interface; and

[0030] • The second end is provided with at least a third optical interface;

[0031] -The second optical splitter-combiner has:

[0032] • The third end, which is provided with at least a fourth optical interface and a fifth optical interface; and

[0033] • The fourth end has at least a sixth optical interface;

[0034] - The InP-based polarization processing unit includes a combined InP-based polarization separator and rotator device having a third optical input port, a first optical output port, and a second optical output port; and

[0035] -The plurality of semiconductor-based optical waveguides include:

[0036] • A first semiconductor-based optical waveguide is arranged to optically connect a first fiber-to-chip coupling location of the at least three fiber-to-chip coupling locations to a first optical interface of the first optical splitter-combiner;

[0037] • A second semiconductor-based optical waveguide is arranged to optically connect a second fiber-to-chip coupling position of the at least three fiber-to-chip coupling positions to a third optical input port of the combined InP-based polarization separator and rotator device;

[0038] • A third semiconductor-based optical waveguide is arranged to optically connect the third fiber-to-chip coupling position of the at least three fiber-to-chip coupling positions to the fourth optical interface of the second optical splitter-combiner;

[0039] • A fourth semiconductor-based optical waveguide is arranged to optically connect the first optical output port of the combined InP-based polarization splitter and rotator device to the second optical interface of the first optical splitter-combiner.

[0040] • A fifth semiconductor-based optical waveguide is arranged to optically connect the second optical output port of the combined InP-based polarization splitter and rotator device to the fifth optical interface of the second optical splitter-combiner;

[0041] A sixth semiconductor-based optical waveguide is arranged to optically connect the third optical interface of the first optical splitter-combiner to the first optical input port of the first optical receiver; and

[0042] • A seventh semiconductor-based optical waveguide is arranged to optically connect the sixth optical interface of the second optical splitter-combiner to the second optical input port of the second optical receiver.

[0043] The embodiments of the PIC defined above according to the present invention can be operated according to the first and second exemplary use cases described above. Operating the embodiments of the PIC defined above according to the third exemplary use case providing a hybrid polarization processing solution is not possible because, on the one hand, the first optical splitter-combiner is arranged between the combined InP-based polarization separator and rotator device of the on-chip InP-based polarization processing unit and the first optical receiver, and on the other hand, the second optical splitter-combiner is arranged between the combined InP-based polarization separator and rotator device of the on-chip InP-based polarization processing unit and the second optical receiver.

[0044] Those skilled in the art will understand that, depending on the specific requirements of the PIC, any suitable number of three or more fiber-to-chip coupling locations, any suitable number of one or more combined InP-based polarization splitter and rotator devices, any suitable number of two or more optical splitter-combiner devices, any suitable number of two or more optical receivers, and any suitable number of semiconductor-based optical waveguides can be envisioned.

[0045] In an embodiment of the PIC according to the present invention:

[0046] - The first optical receiver of the at least two optical receivers has a first optical input port;

[0047] - The second optical receiver of the at least two optical receivers has a second optical input port;

[0048] -The first optical splitter-combiner has:

[0049] • The first end, which is provided with at least a first optical interface and a second optical interface; and

[0050] • The second end is provided with at least a third optical interface;

[0051] -The second optical splitter-combiner has:

[0052] • The third end, which is provided with at least a fourth optical interface and a fifth optical interface; and

[0053] • The fourth end has at least a sixth optical interface;

[0054] - The InP-based polarization processing unit includes:

[0055] • An InP-based polarization separator with a fourth optical input port and a third optical output port.

[0056] The output port and the fourth optical output port; and

[0057] • An InP-based polarization rotator with a fifth optical input port and a fifth optical output port.

[0058] Output port; and

[0059] -The plurality of semiconductor-based optical waveguides include:

[0060] • A first semiconductor-based optical waveguide is arranged to optically connect a first fiber-to-chip coupling location of the at least three fiber-to-chip coupling locations to a first optical interface of the first optical splitter-combiner;

[0061] • A second semiconductor-based optical waveguide is arranged to optically connect the second fiber-to-chip coupling position of the at least three fiber-to-chip coupling positions to the fourth optical input port of the InP-based polarization separator;

[0062] • A third semiconductor-based optical waveguide is arranged to optically connect the third fiber-to-chip coupling position of the at least three fiber-to-chip coupling positions to the fourth optical interface of the second optical splitter-combiner;

[0063] A fourth semiconductor-based optical waveguide is arranged to connect the third optical output port of the InP-based polarization separator to the fifth optical input port of the InP-based polarization rotator.

[0064] Port optical connection;

[0065] A fifth semiconductor-based optical waveguide is arranged to connect the fourth optical output port of the InP-based polarization separator to the fifth optical interface of the second optical splitter-combiner.

[0066] Optical connection;

[0067] A sixth semiconductor-based optical waveguide is arranged to connect the fifth optical output port of the InP-based polarization rotator to the second optical interface of the first optical splitter-combiner.

[0068] Optical connection;

[0069] • A seventh semiconductor-based optical waveguide is arranged to optically connect the third optical interface of the first optical splitter-combiner to the first optical input port of the first optical receiver;

[0070] as well as

[0071] • An eighth semiconductor-based optical waveguide is arranged to optically connect the sixth optical interface of the second optical splitter-combiner to the second optical input port of the second optical receiver.

[0072] The embodiments of the PIC defined above according to the present invention can be operated according to the first and second exemplary use cases described above. Operating the embodiments of the PIC defined above according to the third exemplary use case providing a hybrid polarization processing solution is not possible because the first optical splitter-combiner is arranged between the InP-based polarization rotator of the on-chip InP-based polarization processing unit and the first optical receiver.

[0073] Those skilled in the art will understand that, depending on the specific requirements of the PIC, any suitable number of three or more fiber-to-chip coupling locations, any suitable number of one or more InP-based polarization splitters, any suitable number of one or more polarization rotators, any suitable number of two or more optical splitter-combiners, any suitable number of two or more optical receivers, and any suitable number of semiconductor-based optical waveguides can be envisioned.

[0074] In an embodiment of the PIC according to the present invention:

[0075] - The first optical receiver of the at least two optical receivers has a first optical input port;

[0076] - The second optical receiver of the at least two optical receivers has a second optical input port;

[0077] -The first optical splitter-combiner has:

[0078] • The first end, which is provided with at least a first optical interface and a second optical interface; and

[0079] • The second end is provided with at least a third optical interface;

[0080] -The second optical splitter-combiner has:

[0081] • The third end, which is provided with at least a fourth optical interface and a fifth optical interface; and

[0082] • The fourth end has at least a sixth optical interface;

[0083] - The InP-based polarization processing unit includes:

[0084] • An InP-based polarization separator with a fourth optical input port and a third optical input port.

[0085] Output port and fourth optical output port; and

[0086] • An InP-based polarization rotator with a fifth optical input port and a fifth optical...

[0087] Output ports; and

[0088] -The plurality of semiconductor-based optical waveguides include:

[0089] • A first semiconductor-based optical waveguide is arranged to combine a first fiber-to-chip coupling location of the at least three fiber-to-chip coupling locations with the first optical splitter.

[0090] The device's first optical interface is optically connected;

[0091] • A second semiconductor-based optical waveguide is arranged to separate the second fiber-to-chip coupling position of the at least three fiber-to-chip coupling positions from the InP-based polarization.

[0092] The fourth optical input port of the device is optically connected;

[0093] A third semiconductor-based optical waveguide is arranged to combine the third fiber-to-chip coupling location of the at least three fiber-to-chip coupling locations with the second optical splitter.

[0094] The fourth optical interface of the device is optically connected;

[0095] A fourth semiconductor-based optical waveguide is arranged to connect the third optical output port of the InP-based polarization splitter to the second optical interface of the first optical splitter-combiner.

[0096] Optical connection;

[0097] A fifth semiconductor-based optical waveguide is arranged to connect the fourth optical output port of the InP-based polarization splitter to the fifth optical interface of the second optical splitter-combiner.

[0098] Optical connection;

[0099] A sixth semiconductor-based optical waveguide is arranged to connect the third optical interface of the first optical splitter-combiner to the fifth optical input of the InP-based polarization rotator.

[0100] Optical connection;

[0101] A seventh semiconductor-based optical waveguide is arranged to connect the fifth optical output port of the InP-based polarization rotator to the first optical input port of the first optical receiver.

[0102] Optical connection; and

[0103] • An eighth semiconductor-based optical waveguide is arranged to optically connect the sixth optical interface of the second optical splitter-combiner to the second optical input port of the second optical receiver.

[0104] The embodiments of the PIC defined above according to the present invention can be operated according to the first and third exemplary use cases described above. Operating the embodiments of the PIC defined above according to the second exemplary use case described above, which provides a fully on-chip polarization processing solution, is not possible because the InP-based polarization rotator of the on-chip InP-based polarization processing unit is arranged between the first optical splitter-combiner and the first optical receiver. Therefore, only polarization separation can be performed entirely off-chip.

[0105] Those skilled in the art will understand that, depending on the specific requirements of the PIC, any suitable number of three or more fiber-to-chip coupling locations, any suitable number of one or more InP-based polarization splitters, any suitable number of one or more polarization rotators, any suitable number of two or more optical splitter-combiners, any suitable number of two or more optical receivers, and any suitable number of semiconductor-based optical waveguides can be envisioned.

[0106] In embodiments of the PIC according to the invention, the at least two optical receivers are coherent optical receivers or are configured to recover information from optical signals encoded using amplitude modulation. An example of a suitable modulation format using amplitude modulation is on-off-keying (OOK).

[0107] In one embodiment of the PIC according to the invention, at least a first and a third fiber-to-chip coupling position of at least three fiber-to-chip coupling positions are arranged separately at a distance ranging from 20 μm to 1000 μm, preferably from 250 μm to 500 μm. Those skilled in the art will recognize that the distance between the first and third fiber-to-chip coupling positions within the aforementioned range allows for the simultaneous coupling of optical fibers to at least both the first and third fiber-to-chip coupling positions using fiber arrays or fiber blocks. This can contribute to improving the ease of use of the PIC according to the invention.

[0108] In one embodiment of the PIC according to the invention, the at least three fiber-to-chip coupling locations are arranged on the same surface of the PIC. This also contributes to improving the ease of use of the PIC according to the invention.

[0109] In embodiments of the PIC according to the present invention, at least one of the at least two optical splitter-combiners is a thermally tunable optical splitter-combiner or an electro-optically tunable optical splitter-combiner. Those skilled in the art will understand that thermally tunable or electro-optically tunable optical splitter-combiners can be used to actively optimize the coupling efficiency of a given waveguide path.

[0110] In embodiments of the PIC according to the invention, at least one of the at least two optical splitter-combiner is a multimode interference (MMI) based coupler. The respective ends of the MMI-based coupler can have any suitable number of optical interfaces. Therefore, the MMI-based coupler can be implemented as any suitable nxm MMI-based coupler, such as a 1x2 MMI-based coupler or a 2x2 MMI-based coupler. One advantage of using a 1x2 MMI-based coupler is that it gives equal priority to the on-chip and off-chip polarization processing solutions provided by the PIC. This means that any of these solutions will result in a basic 3dB loss. An advantage of using a 2x2 MMI-based coupler is that it allows for the addition of additional components to the PIC, such as semiconductor optical amplifiers (SOAs) and / or additional polarization rotators. These additional components can be used, for example, to achieve improved alignment of the fiber and fiber-to-chip coupling positions, and at least one of the characteristics described in the InP-based polarization processing components of the PIC.

[0111] In one embodiment of the PIC according to the present invention, the MMI-based coupler is a thermally tunable MMI-based coupler or an electro-optically tunable MMI-based coupler. Similar to the above, it should be understood that thermally tunable MMI-based couplers or electro-optically tunable MMI-based couplers can be used to actively optimize the coupling efficiency of a given waveguide path.

[0112] In an embodiment of the PIC according to the invention, the MMI-based coupler is configured and arranged as an asymmetric MMI-based coupler. An advantage of using an asymmetric MMI-based coupler (e.g., 85%:15%) is that one of the waveguide paths optically connected to the MMI-based coupler is advantageous.

[0113] In one embodiment of the PIC according to the present invention, at least one of the first semiconductor-based optical waveguide at the first fiber-to-chip coupling location, the second semiconductor-based optical waveguide at the second fiber-to-chip coupling location, and the third semiconductor-based optical waveguide at the third fiber-to-chip coupling location is provided with a tapered portion. The tapered portion can be configured and arranged to achieve spot size conversion of optical radiation to improve the coupling efficiency at the optical interface between the corresponding semiconductor-based optical waveguide and the corresponding optical fiber at the corresponding fiber-to-chip coupling location of the PIC according to the present invention.

[0114] In an embodiment of the PIC according to the present invention, at least one of the at least two optical receivers, at least two optical splitters-combiners, and a plurality of semiconductor-based optical waveguides comprise InP-based semiconductor materials.

[0115] In one embodiment of the PIC according to the invention, the PIC is a hybrid PIC or an InP-based monolithic PIC. The hybrid PIC allows the advantages of the invention to be applied to both III-V photonics and silicon photonics. In a single-process mode, the hybrid PIC can include photonic components made of III-V semiconductor materials (e.g., InP-based semiconductor materials) and photonic components made of IV semiconductor materials (e.g., Si-based semiconductor materials). An advantage of the hybrid PIC according to the invention is, for example, the ability to replace photonic components in case of failure or damage. An advantage of the InP-based monolithic PIC is that active components (e.g., light-generating and / or light-absorbing optics) and passive components (e.g., light-guiding and / or light-switching optics) are integrated on the same semiconductor substrate in a single-process mode. Therefore, the fabrication of the InP-based monolithic PIC can be less complex and thus cheaper than the assembly of the hybrid PIC, which requires assembly steps to achieve a hybrid interconnection of active and passive optoelectronic devices, each typically fabricated on a different substrate. Furthermore, the InP-based monolithic PIC allows for a smaller overall size than the hybrid PIC.

[0116] According to another aspect of the invention, an optoelectronic system is provided, which includes a PIC according to the invention. For example, the optoelectronic system can be used in, but is not limited to, telecommunications applications, LIDAR, or sensor applications. The optoelectronic system can be one of a receiver, a transceiver, a coherent receiver, and a coherent transceiver. Attached Figure Description

[0117] Further features and advantages of the invention will become apparent from the description of exemplary and non-limiting embodiments of the PIC and optoelectronic systems including such PIC according to the invention.

[0118] Those skilled in the art will understand that the described embodiments of the PIC and optoelectronic systems are merely exemplary in nature and should not be construed as limiting the scope of protection in any way. Those skilled in the art will recognize that alternative and equivalent embodiments of the PIC and optoelectronic systems can be conceived and practiced without departing from the scope of protection of this invention.

[0119] Please refer to the accompanying drawings in the accompanying drawings page. These drawings are schematic in nature and therefore not necessarily drawn to scale. In addition, the same reference numerals indicate the same or similar parts.

[0120] In the attached pages:

[0121] Figure 1 A schematic top view of a first exemplary, non-limiting embodiment of a PIC according to the present invention, operating according to a first exemplary use case, is shown;

[0122] Figure 2 A schematic top view of a first exemplary, non-limiting embodiment of a PIC according to the present invention, operating according to a second exemplary use case, is shown;

[0123] Figure 3 A schematic top view of a second exemplary, non-limiting embodiment of a PIC according to the present invention, operating according to a first exemplary use case, is shown;

[0124] Figure 4 A schematic top view of a second exemplary, non-limiting embodiment of a PIC according to the present invention, operating according to a second exemplary use case, is shown;

[0125] Figure 5 A schematic top view of a third exemplary, non-limiting embodiment of a PIC according to the present invention, operating according to a first exemplary use case, is shown;

[0126] Figure 6 A schematic top view of a third exemplary, non-limiting embodiment of a PIC according to the present invention, operating according to a third exemplary use case, is shown;

[0127] Figure 7 A schematic top view of a third exemplary, non-limiting embodiment of the PIC according to the present invention, operating according to a fourth exemplary use case, is shown;

[0128] Figure 8 A schematic top view of a fourth exemplary, non-limiting embodiment of the PIC according to the present invention, operating according to a first exemplary use case, is shown; and

[0129] Figure 9 A schematic top view of a first exemplary, non-limiting embodiment of an optoelectronic system including a PIC according to the present invention is shown. Detailed Implementation

[0130] Figure 1 A schematic top view of a first exemplary, non-limiting embodiment of a PIC 1 according to the present invention is shown. The PIC 1 includes three fiber-to-chip coupling locations 2, 3, and 4; an InP-based polarization processing unit in the form of a combined InP-based polarization splitter and rotator device 13; two optical splitter-combiners 9 and 11; two optical receivers 5 and 7; and multiple optically interconnected semiconductor-based optical waveguides 19a-19g. The first semiconductor-based optical waveguide 19a is arranged to optically connect the first fiber-to-chip coupling location 2 to a first optical interface 10a at a first end 9a of the first optical splitter-combiner 9. The second semiconductor-based optical waveguide 19b is arranged to optically connect the second fiber-to-chip coupling location 3 to a third optical input port 14a of the combined InP-based polarization splitter and rotator device 13. The third semiconductor-based optical waveguide 19c is arranged to optically connect the third fiber-to-chip coupling location 4 to a fourth optical interface 12a at a third end 11a of the second optical splitter-combiner 11. A fourth semiconductor-based optical waveguide 19d is arranged to optically connect the first optical output port 14b of the combined InP-based polarization splitter and rotator device 13 to the second optical interface 10b at the first end 9a of the first optical splitter-combiner 9. A fifth semiconductor-based optical waveguide 19e is arranged to optically connect the second optical output port 14c of the combined InP-based polarization splitter and rotator device 13 to the fifth optical interface 12b at the third end 11a of the second optical splitter-combiner 11. A sixth semiconductor-based optical waveguide 19f is arranged to optically connect the third optical interface 10c at the second end 9b of the first optical splitter-combiner 9 to the first optical input port 6 of the first optical receiver 5. A seventh semiconductor-based optical waveguide 19g is arranged to optically connect the sixth optical interface 12c at the fourth end 11b of the second optical splitter-combiner 11 to the second optical input port 8 of the second optical receiver 7.

[0131] Figure 1As illustrated in the first exemplary use case providing a fully on-chip polarization processing solution, a first optical fiber 22a is optically connected to the PIC 1 at a second fiber-to-chip coupling location 3. According to the first exemplary use case, the first optical fiber 22a guides optical radiation including TM and TE modes, which is emitted into a second semiconductor-based optical waveguide 19b, which is optically connected to a third optical input port 14a of a combined InP-based polarization splitter and rotator device 13. The combined InP-based polarization splitter and rotator device 13 is configured to first separate the TM and TE modes of the received optical radiation, and then rotate the separated TM mode to obtain a converted TE mode. Subsequently, the converted TE mode is guided to a first optical receiver 5 via a fourth semiconductor-based optical waveguide 19d, a first optical splitter-combiner 9, and a sixth semiconductor-based optical waveguide 19f. The separated TE mode is guided to a second optical receiver 7 via a fifth semiconductor-based optical waveguide 19e, a second optical splitter-combiner 11, and a seventh semiconductor-based optical waveguide 19g.

[0132] Figure 2 A schematic top view of a first exemplary, non-limiting embodiment of PIC 1 is shown, which operates according to the second exemplary use case described above that provides a complete off-chip polarization processing solution. Figure 2 The diagram shows a second optical fiber 22b optically connected to the PIC 1 at the first fiber-to-chip coupling location 2, and a third optical fiber 22c optically connected to the PIC 1 at the third fiber-to-chip coupling location 4. According to a second exemplary use case, the second optical fiber 22b guides optical radiation in TE mode, including off-chip separation and conversion, which is emitted into a first semiconductor-based optical waveguide 19a and guided to a first optical receiver 5 via the first semiconductor-based optical waveguide 19a, a first optical splitter-combiner 9, and a sixth semiconductor-based optical waveguide 19f. According to a second exemplary use case, the third optical fiber 22c guides optical radiation in TE mode, which is emitted into a third semiconductor-based optical waveguide 19c and guided to a second optical receiver 7 via the third semiconductor-based optical waveguide 19c, a second optical splitter-combiner 11, and a seventh semiconductor-based optical waveguide 19g.

[0133] It is obvious that Figure 1 and 2 The embodiment of PIC 1 shown cannot be operated according to the third exemplary use case described above that provides a hybrid polarization processing solution because, on the one hand, the first optical splitter-combiner 9 is arranged between the combined InP-based polarization splitter and rotator device 13 and the first optical receiver 5, and on the other hand, the second optical splitter-combiner 11 is arranged between the combined InP-based polarization splitter and rotator device 13 and the second optical receiver 7.

[0134] Figures 1 to 8 As shown, the first fiber-to-chip coupling position 2 and the third fiber-to-chip coupling position 4 are arranged separately with a distance D. As mentioned above, the distance D can be in the range of 20 μm to 1000 μm, preferably in the range of 250 μm to 500 μm. In this way, a fiber array or fiber block 23 (see...) can be used. Figure 2 , 4 6) Simultaneous coupling is achieved between the second optical fiber 22b and the first optical fiber to chip coupling position 2, and between the third optical fiber 22c and the third optical fiber to chip coupling position 4. As described above, this can help improve the usability of the PIC 1 according to the present invention.

[0135] Figures 1-8 The diagram also shows three fiber-to-chip coupling locations 2, 3, and 4 arranged on the same side 20 of the PIC 1. This also helps improve the ease of use of the PIC 1.

[0136] Figures 1 to 8 The optical splitter-combiners 9 and 11 in the illustrated embodiment of PIC 1 are schematic representations of MMI-based couplers. It should be understood that any suitable type of optical splitter-combiner can be used according to the present invention. Figures 1-7 The diagram shows a 1x2 MMI-based coupler used to implement optical splitter-combiner 9 and 11, while... Figure 8 The diagram shows a 2x2 MMI-based connector used to implement optical splitter-combiner 9, 11. As mentioned above, one advantage of using a 1x2 MMI-based coupler is that it gives equal priority to both on-chip and off-chip polarization processing solutions provided by the PIC. This means that any of these solutions will introduce a basic 3dB loss. The combination... Figure 8 Describe the advantages of using a 2x2 MMI-based coupler.

[0137] Figures 1-8 In the embodiment of PIC 1 shown, optical receivers 5 and 7 can be implemented as coherent optical receivers or configured as conventional optical receivers to recover information from optical signals encoded using amplitude modulation. As mentioned above, an example of a suitable modulation format using amplitude modulation is on-keying (OOK).

[0138] Figure 3A schematic top view of a second exemplary, non-limiting embodiment of a PIC 1 according to the present invention is shown. The PIC 1 includes three fiber-to-chip coupling locations 2, 3, and 4; an InP-based polarization processing unit including an InP-based polarization splitter 15 and an InP-based polarization rotator 17; two optical splitter-combiners 9 and 11; two optical receivers 5 and 7; and multiple optically interconnected semiconductor-based optical waveguides 19a-19h. A first semiconductor-based optical waveguide 19a is arranged to optically connect the first fiber-to-chip coupling location 2 to a first optical interface 10a at a first end 9a of the first optical splitter-combiner 9. A second semiconductor-based optical waveguide 19b is arranged to optically connect the second fiber-to-chip coupling location 3 to a fourth optical input port 16a of the InP-based polarization splitter 15. A third semiconductor-based optical waveguide 19c is arranged to optically connect the third fiber-to-chip coupling location 4 to a fourth optical interface 12a at a third end 11a of the second optical splitter-combiner 11. A fourth semiconductor-based optical waveguide 19d is arranged to optically connect the third optical output port 16b of the InP-based polarization splitter 15 to the fifth optical input port 18a of the InP-based polarization rotator 17. A fifth semiconductor-based optical waveguide 19e is arranged to optically connect the fourth optical output port 16c of the InP-based polarization splitter 15 to the fifth optical interface 12b at the third end 11a of the second optical splitter-combiner 11. A sixth semiconductor-based optical waveguide 19f is arranged to optically connect the fifth optical output port 18b of the InP-based polarization rotator 17 to the second optical interface 10b at the first end 9a of the first optical splitter-combiner 9. A seventh semiconductor-based optical waveguide 19g is arranged to optically connect the third optical interface 10c at the second end 9b of the first optical splitter-combiner 9 to the first optical input port 6 of the first optical receiver 5. The eighth semiconductor-based optical waveguide 19h is arranged to optically connect the sixth optical interface 12c at the fourth end 11b of the second optical splitter-combiner 11 to the second optical input port 8 of the second optical receiver 7.

[0139] Figure 3As illustrated in the first exemplary use case described above, which provides a fully on-chip polarization processing solution, a first optical fiber 22a is optically connected to the PIC 1 at a second fiber-to-chip coupling location 3. According to the first exemplary use case, the first optical fiber 22a guides optical radiation comprising TM and TE modes, which is emitted into a second semiconductor-based optical waveguide 19b, which is optically connected to a fourth optical input port 16a of an InP-based polarization separator 15. The InP-based polarization separator 15 is configured to separate the TM and TE modes of the received optical radiation. The separated TM mode is guided via a fourth semiconductor-based optical waveguide 19d to an InP-based polarization rotator 17. The InP-based polarization rotator 17 is configured to rotate the separated TM mode to obtain a converted TE mode. Subsequently, the converted TE mode is guided to a first optical receiver 5 via a sixth semiconductor-based optical waveguide 19f, a first optical splitter-combiner 9, and a seventh semiconductor-based optical waveguide 19g. The separated TE mode is guided to the second optical receiver 7 via the fifth semiconductor-based optical waveguide 19e, the second optical splitter-combiner 11 and the eighth semiconductor-based optical waveguide 19h.

[0140] Figure 4 A schematic top view of a second exemplary, non-limiting embodiment of PIC 1 is shown, which operates according to the aforementioned second exemplary use case that provides a complete off-chip polarization processing solution. Figure 4 The second optical fiber 22b is shown to be optically connected to PIC 1 at the first fiber-to-chip coupling location 2, and the third optical fiber 22c is optically connected to PIC 1 at the third fiber-to-chip coupling location 4 using an optical fiber array or fiber block 23. According to a second exemplary use case, the second optical fiber 22b guides optical radiation including off-chip splitting and conversion in TE mode, which is emitted into a first semiconductor-based optical waveguide 19a and guided to a first optical receiver 5 via the first semiconductor-based optical waveguide 19a, a first optical splitter-combiner 9, and a seventh semiconductor-based optical waveguide 19g. According to a second exemplary use case, the third optical fiber 22c guides optical radiation including off-chip splitting in TE mode, which is emitted into a third semiconductor-based optical waveguide 19c and guided to a second optical receiver 7 via the third semiconductor-based optical waveguide 19c, a second optical splitter-combiner 11, and an eighth semiconductor-based optical waveguide 19h.

[0141] It is obvious that Figure 3 and 4 The embodiment of PIC 1 shown cannot be operated according to the third exemplary use case described above that provides a hybrid polarization processing solution because the first optical splitter-combiner 9 is arranged between the InP-based polarization rotator 17 and the first optical receiver 5.

[0142] Figure 5 A schematic top view of a third exemplary, non-limiting embodiment of a PIC 1 according to the present invention is shown. The PIC 1 includes three fiber-to-chip coupling locations 2, 3, and 4; an InP-based polarization processing unit including an InP-based polarization splitter 15 and an InP-based polarization rotator 17; two optical splitter-combiners 9 and 11; two optical receivers 5 and 7; and multiple optically interconnected semiconductor-based optical waveguides 19a-19h. A first semiconductor-based optical waveguide 19a is arranged to optically connect the first fiber-to-chip coupling location 2 to a first optical interface 10a at a first end 9a of the first optical splitter-combiner 9. A second semiconductor-based optical waveguide 19b is arranged to optically connect the second fiber-to-chip coupling location 3 to a fourth optical input port 16a of the InP-based polarization splitter 15. A third semiconductor-based optical waveguide 19c is arranged to optically connect the third fiber-to-chip coupling location 4 to a fourth optical interface 12a at a third end 11a of the second optical splitter-combiner 11. A fourth semiconductor-based optical waveguide 19d is arranged to optically connect the third optical output port 16b of the InP-based polarization splitter 15 to the second optical interface 10b at the first end 9a of the first optical splitter-combiner 9. A fifth semiconductor-based optical waveguide 19e is arranged to optically connect the fourth optical output port 16c of the InP-based polarization splitter 15 to the fifth optical interface 12b at the third end 11a of the second optical splitter-combiner 11. A sixth semiconductor-based optical waveguide 19f is arranged to optically connect the third optical interface 10c at the second end 9b of the first optical splitter-combiner 9 to the fifth optical input port 18a of the InP-based polarization rotator 17. A seventh semiconductor-based optical waveguide 19g is arranged to optically connect the fifth optical output port 18b of the InP-based polarization rotator 17 to the first optical input port 6 of the first optical receiver 5. The eighth semiconductor-based optical waveguide 19h is arranged to optically connect the sixth optical interface 12c at the fourth end 11b of the second optical splitter-combiner 11 to the second optical input port 8 of the second optical receiver 7.

[0143] Figure 5As illustrated in the first exemplary use case described above, which provides a fully on-chip polarization processing solution, a first optical fiber 22a is optically connected to the PIC 1 at a second fiber-to-chip coupling location 3. According to the first exemplary use case, the first optical fiber 22a guides optical radiation comprising TM and TE modes, which is emitted into a second semiconductor-based optical waveguide 19b, which is optically connected to a fourth optical input port 16a of an InP-based polarization separator 15. The InP-based polarization separator 15 is configured to separate the TM and TE modes of the received optical radiation. The separated TM mode is guided to an InP-based polarization rotator 17 via a fourth semiconductor-based optical waveguide 19d, a first optical splitter-combiner 9, and a sixth semiconductor-based optical waveguide 19f. The InP-based polarization rotator 17 is configured to rotate the separated TM mode to obtain a converted TE mode. Subsequently, the converted TE mode is guided to a first optical receiver 5 via a seventh semiconductor-based optical waveguide 19g. The separated TE mode is guided to the second optical receiver 7 via the fifth semiconductor-based optical waveguide 19e, the second optical splitter-combiner 11 and the eighth semiconductor-based optical waveguide 19h.

[0144] Figure 6 A schematic top view of a third exemplary, non-limiting embodiment of PIC 1 is shown, which operates according to the aforementioned third exemplary use case providing a hybrid polarization processing solution. Figure 6 The second optical fiber 22b is shown to be optically connected to the PIC 1 at the first fiber-to-chip coupling location 2, and the third optical fiber 22c is optically connected to the PIC 1 at the third fiber-to-chip coupling location 4 using an optical fiber array or fiber block 23. According to a third exemplary use case, the second optical fiber 22b guides optical radiation including an off-chip separated TM mode, which is emitted into a first semiconductor-based optical waveguide 19a and guided via the first semiconductor-based optical waveguide 19a, a first optical splitter-combiner 9, and a sixth semiconductor-based optical waveguide 19f to an InP-based polarization rotator 17. The InP-based polarization rotator 17 is configured to rotate the separated TM mode to obtain a converted TE mode. Subsequently, the converted TE mode is guided to a first optical receiver 5 via a seventh semiconductor-based optical waveguide 19g. According to a third exemplary use case, the third optical fiber 22c guides optical radiation including off-chip discrete TE mode, which is emitted into a third semiconductor-based optical waveguide 19c and guided to a second optical receiver 7 via the third semiconductor-based optical waveguide 19c, the second optical splitter-combiner 11 and the eighth semiconductor-based optical waveguide 19h.

[0145] It is obvious that Figure 5 and 6The embodiment of PIC 1 shown cannot be operated according to the second exemplary use case described above, which provides a completely off-chip polarization processing solution, because the InP-based polarization rotator 17 is arranged between the first optical splitter-combiner 9 and the first optical receiver 5. Therefore, only polarization separation can be performed entirely off-chip.

[0146] Figure 7 A schematic top view of a third exemplary, non-limiting embodiment of PIC 1 is shown, which operates according to a fourth exemplary use case providing a single polarization processing solution. Similar to the common practice employed by large electronics chip suppliers, where a single, fully functional chip is designed and then suppressed to varying degrees during assembly to create a range of products, such as telephone processors, the PIC 1 according to the invention can be used in a single polarization mode without suffering, for example, optical insertion loss associated with an InP-based polarization separator 15.

[0147] Figure 7 The third optical fiber 22c is shown to be optically connected to the PIC 1 at the third optical fiber-to-chip coupling location 4. According to a fourth exemplary use case, the third optical fiber 22c guides only TE mode optical radiation, which is emitted into the third semiconductor-based optical waveguide 19c and guided to the second optical receiver 7 via the third semiconductor-based optical waveguide 19c, the second optical splitter-combiner 11, and the eighth semiconductor-based optical waveguide 19h. It should be understood that... Figures 1-4 The embodiment of PIC 1 shown in Figure 8 can also be operated according to the fourth exemplary use case described above.

[0148] It should be noted that in the case of PICs that include InP-based components (e.g., at least one of optical receivers, optical splitters-combiners, and semiconductor-based optical waveguides), these PICs are typically optimized for handling TE modes due to the confined nature of the quantum well, and the fifth exemplary use case, in which optical radiation only includes TM modes, is not possible. However, PICs that do not include InP-based components can operate according to this fifth exemplary use case.

[0149] Figure 8A schematic top view of a fourth exemplary, non-limiting embodiment of a PIC 1 according to the present invention is shown. The PIC 1 includes three fiber-to-chip coupling locations 2, 3, and 4; an InP-based polarization processing unit including an InP-based polarization splitter 15 and an InP-based polarization rotator 17 and an additional InP-based polarization rotator 24; two optical splitter-combiners 9 and 11; two semiconductor optical amplifiers (SOAs) 26 and 28; two optical receivers 5 and 7; and multiple optically interconnected semiconductor-based optical waveguides 19a-19k. A first semiconductor-based optical waveguide 19a is arranged to optically connect the first fiber-to-chip coupling location 2 to a first optical interface 10a at a first end 9a of the first optical splitter-combiner 9. A second semiconductor-based optical waveguide 19b is arranged to optically connect the second fiber-to-chip coupling location 3 to a fourth optical input port 16a of the InP-based polarization splitter 15. The second semiconductor-based optical waveguide 19b is provided with a tapered portion 21, which is disposed at the second fiber-to-chip coupling location 3. The tapered portion 21 can be configured and arranged to achieve spot size conversion of optical radiation to improve the coupling efficiency at the optical interface between the second semiconductor-based optical waveguide 19b and the first optical fiber 22a at the second fiber-to-chip coupling location 3. It should be understood that, according to other exemplary embodiments of the PIC, any one of the first semiconductor-based optical waveguide 19a, the second semiconductor-based optical waveguide 19b, and the third semiconductor-based optical waveguide 19c may be provided with a tapered portion. The third semiconductor-based optical waveguide 19c is arranged to optically connect the third fiber-to-chip coupling location 4 to the fourth optical interface 12a at the third end 11a of the second optical splitter-combiner 11. The fourth semiconductor-based optical waveguide 19d is arranged to optically connect the third optical output port 16b of the InP-based polarization separator 15 to the second optical interface 10b at the first end 9a of the first optical splitter-combiner 9. A fifth semiconductor-based optical waveguide 19e is arranged to optically connect the fourth optical output port 16c of the InP-based polarization splitter 15 to the fifth optical interface 12b at the third end 11a of the second optical splitter-combiner 11. A sixth semiconductor-based optical waveguide 19f is arranged to optically connect the third optical interface 10c at the second end 9b of the first optical splitter-combiner 9 to the fifth optical input port 18a of the InP-based polarization rotator 17. A seventh semiconductor-based optical waveguide 19g is arranged to optically connect the fifth optical output port 18b of the InP-based polarization rotator 17 to the first optical input interface 6 of the first optical receiver 5. An eighth semiconductor-based optical waveguide 19h is arranged to optically connect the sixth optical interface 12c at the fourth end 11b of the second optical splitter-combiner 11 to the second optical input port 8 of the second optical receiver 7.The ninth semiconductor-based optical waveguide 19i is arranged to optically connect the fourth optical interface 10d at the second end 9b of the first optical splitter-combiner 9 to the sixth optical input port 25a of the additional InP-based polarization rotator 24. The tenth semiconductor-based optical waveguide 19j is arranged to optically connect the sixth optical output port 25b of the additional InP-based polarization rotator 24 to the seventh optical input port 27 of the first SOA 26. The eleventh semiconductor-based optical waveguide 19k is arranged to optically connect the seventh optical interface 12d at the fourth end 11b of the second optical splitter-combiner 11 to the eighth optical input port 29 of the second SOA 28.

[0150] Figure 8 As illustrated in the first exemplary use case providing a fully on-chip polarization processing solution, a first optical fiber 22a is optically connected to the PIC 1 at a second fiber-to-chip coupling location 3. According to the first exemplary use case, the first optical fiber 22a guides optical radiation comprising TM and TE modes, which is emitted into a second semiconductor-based optical waveguide 19b, optically connected to a fourth optical input port 16a of an InP-based polarization separator 15. The InP-based polarization separator 15 is configured to separate the TM and TE modes of the received optical radiation. The separated TM mode is guided to an InP-based polarization rotator 17 via a fourth semiconductor-based optical waveguide 19d, a first optical splitter-combiner 9, and a sixth semiconductor-based optical waveguide 19f. The InP-based polarization rotator 17 is configured to rotate the separated TM mode to obtain a converted TE mode. Subsequently, the converted TE mode is guided to a first optical receiver 5 via a seventh semiconductor-based optical waveguide 19g. The separated TE mode is guided to the second optical receiver 7 via the fifth semiconductor-based optical waveguide 19e, the second optical splitter-combiner 11 and the eighth semiconductor-based optical waveguide 19h.

[0151] A schematic representation of the first optical splitter-combiner 9 and the second optical splitter-combiner 11 based on a 2x2 MMI coupler. Figures 1-7Compared to the illustrated embodiment of PIC 1, implementing the first optical splitter-combiner 9 and the second optical splitter-combiner 11 as a 2x2 MMI-based coupler allows for the addition of additional components to PIC 1, namely, an InP-based polarization rotator 24, a first SOA 26, and a second SOA 28. These additional components can, for example, be used to characterize at least one of the InP-based polarization processing components of PIC 1 and to improve the alignment of the fiber and fiber-to-chip coupling positions. Optically coupling the fiber to the fiber-to-chip coupling position can be a challenging and time-consuming process. Forwardly biasing the first SOA 26 and the second SOA 28 will result in optical radiation, which is a result of spontaneous emission from fiber-to-chip coupling positions 2, 3, and 4 at facet 20 of PIC 1. This can improve the initial alignment of the first fiber 22a and the third fiber-to-chip coupling position 3. Similarly, by reverse biasing at least one of the first SOA26 and the second SOA28, on-chip optical power monitoring can be achieved, which enables on-chip characterization of at least InP-based polarization processing components of the PIC 1.

[0152] Figure 9 A schematic top view of a first exemplary, non-limiting embodiment of an optoelectronic system 100 including a PIC 1 according to the present invention is shown. For example, the optoelectronic system 100 can be used in, but is not limited to, telecommunications applications, LIDAR, or sensor applications. The optoelectronic system 100 can, for example, be one of a receiver, transceiver, coherent receiver, and coherent transceiver.

[0153] This invention can be summarized as relating to a PIC 1, which includes at least three fiber-to-chip coupling locations 2, 3, and 4, an InP-based polarization processing unit, at least two optical splitter-combiners 9 and 11, at least two optical receivers 5 and 7, and a plurality of semiconductor-based optical waveguides. The plurality of semiconductor-based optical waveguides are configured and arranged to optically connect a first fiber-to-chip coupling location 2 to a first optical receiver 5 via a first optical splitter-combiner 9, to a second fiber-to-chip coupling location 3 to at least two optical receivers 5 and 7 via the InP-based polarization processing unit and at least two optical splitter-combiners 9 and 11, and to a third fiber-to-chip coupling location 4 to a second optical receiver 7 via a second optical splitter-combiner 11. This invention also relates to an optoelectronic system 100 including said PIC 1.

[0154] Those skilled in the art will recognize that the scope of the invention is not limited to the embodiments discussed above, but that various modifications and variations can be made therein without departing from the scope of the invention as defined by the appended claims. In particular, specific features of various aspects of the invention can be combined. One aspect of the invention can be further advantageously enhanced by adding features described with respect to another aspect of the invention. Although the invention has been detailed and described in the accompanying drawings and specification, such illustrations and descriptions are to be considered illustrative or exemplary only, and not restrictive.

[0155] This invention is not limited to the disclosed embodiments. By studying the drawings, description, and appended claims, those skilled in the art can understand and implement variations of the disclosed embodiments in practicing the claimed invention. In the claims, the word "comprising" does not exclude other steps or elements, and the indefinite articles "a" or "an" do not exclude multiple. The fact that certain measures are recited in mutually different dependent claims does not mean that combinations of these measures cannot be used advantageously. Any reference numerals in the claims should not be construed as limiting the scope of the invention.

Claims

1. A photonic integrated circuit PIC (1), comprising: At least three fiber optic coupling points to the chip (2, 3, 4); The InP-based polarization processing unit includes an InP-based polarization separator and an InP-based polarization rotator. The InP-based polarization separator is used to separate the received light radiation into a transverse magnetic TM mode and a transverse electric TE mode. The InP-based polarization rotator is used to rotate the separated TM mode light radiation to obtain the converted TE mode light radiation. At least two optical splitter-combiner (9, 11). At least two optical receivers (5, 7); and Multiple semiconductor-based optical waveguides (19a-19k); The plurality of semiconductor-based optical waveguides are configured and arranged as follows: The first fiber-to-chip coupling position (2) of the at least three fiber-to-chip coupling positions is optically connected to the first optical receiver (5) of the at least two optical receivers via the first optical splitter-combiner (9) of the at least two optical splitters-combiners; The second fiber-to-chip coupling position (3) of the at least three fiber-to-chip coupling positions is optically connected to the at least two optical receivers (5, 7) via the InP-based polarization processing unit and the at least two optical splitter-combiner (9, 11). as well as The third fiber-to-chip coupling position (4) of the at least three fiber-to-chip coupling positions is optically connected to the second optical receiver (7) of the at least two optical receivers via the second optical splitter-combiner (11) of the at least two optical splitter-combiner.

2. The PIC (1) according to claim 1, wherein: The first optical receiver (5) of the at least two optical receivers has a first optical input port (6); The second optical receiver (7) of the at least two optical receivers has a second optical input port (8); The first optical splitter-combiner (9) has: The first end (9a) is provided with at least a first optical interface (10a) and a second optical interface (10b); and The second end (9b) is provided with at least a third optical interface (10c). The second optical splitter-combiner (11) has: The third end (11a) is provided with at least a fourth optical interface (12a) and a fifth optical interface (12b); and The fourth end (11b) is provided with at least a sixth optical interface (12c); The InP-based polarization processing unit includes a combined InP-based polarization separator and rotator device (13) having a third optical input port (14a), a first optical output port (14b), and a second optical output port (14c). as well as The plurality of semiconductor-based optical waveguides include: A first semiconductor-based optical waveguide (19a) is arranged to optically connect the first fiber-to-chip coupling position (2) of the at least three fiber-to-chip coupling positions to the first optical interface (10a) of the first optical splitter-combiner (9). The second semiconductor-based optical waveguide (19b) is arranged to optically connect the second fiber-to-chip coupling position (3) of the at least three fiber-to-chip coupling positions to the third optical input port (14a) of the combined InP-based polarization separator and rotator device (13). A third semiconductor-based optical waveguide (19c) is arranged to optically connect the third fiber-to-chip coupling position (4) of the at least three fiber-to-chip coupling positions to the fourth optical interface (12a) of the second optical splitter-combiner (11). A fourth semiconductor-based optical waveguide (19d) is arranged to optically connect the first optical output port (14b) of the combined InP-based polarization splitter and rotator device (13) to the second optical interface (10b) of the first optical splitter-combiner (9). The fifth semiconductor-based optical waveguide (19e) is arranged to optically connect the second optical output port (14c) of the combined InP-based polarization splitter and rotator device (13) to the fifth optical interface (12b) of the second optical splitter-combiner (11). A sixth semiconductor-based optical waveguide (19f) is arranged to optically connect the third optical interface (10c) of the first optical splitter-combiner (9) to the first optical input port (6) of the first optical receiver (5); and The seventh semiconductor-based optical waveguide (19g) is arranged to optically connect the sixth optical interface (12c) of the second optical splitter-combiner (11) to the second optical input port (8) of the second optical receiver (7).

3. The PIC (1) according to claim 1, wherein: The first optical receiver (5) of the at least two optical receivers has a first optical input port (6); The second optical receiver (7) of the at least two optical receivers has a second optical input port (8); The first optical splitter-combiner (9) has: The first end (9a) is provided with at least a first optical interface (10a) and a second optical interface (10b); and The second end (9b) is provided with at least a third optical interface (10c). The second optical splitter-combiner (11) has: The third end (11a) is provided with at least a fourth optical interface (12a) and a fifth optical interface (12b); and The fourth end (11b) is provided with at least a sixth optical interface (12c); The InP-based polarization processing unit includes: An InP-based polarization separator (15) has a fourth optical input port (16a), a third optical output port (16b), and a fourth optical output port (16c); and A polarization rotator (17) based on InP, having a fifth optical input port (18a) and a fifth optical output port (18b); and The plurality of semiconductor-based optical waveguides include: A first semiconductor-based optical waveguide (19a) is arranged to optically connect the first fiber-to-chip coupling position (2) of the at least three fiber-to-chip coupling positions to the first optical interface (10a) of the first optical splitter-combiner (9). The second semiconductor-based optical waveguide (19b) is arranged to optically connect the second fiber-to-chip coupling position (3) of the at least three fiber-to-chip coupling positions to the fourth optical input port (16a) of the InP-based polarization separator (15). A third semiconductor-based optical waveguide (19c) is arranged to optically connect the third fiber-to-chip coupling position (4) of the at least three fiber-to-chip coupling positions to the fourth optical interface (12a) of the second optical splitter-combiner (11). A fourth semiconductor-based optical waveguide (19d) is arranged to optically connect the third optical output port (16b) of the InP-based polarization separator (15) to the fifth optical input port (18a) of the InP-based polarization rotator (17). The fifth semiconductor-based optical waveguide (19e) is arranged to optically connect the fourth optical output port (16c) of the InP-based polarization separator (15) to the fifth optical interface (12b) of the second optical splitter-combiner (11). The sixth semiconductor-based optical waveguide (19f) is arranged to optically connect the fifth optical output port (18b) of the InP-based polarization rotator (17) to the second optical interface (10b) of the first optical splitter-combiner (9); A seventh semiconductor-based optical waveguide (19g) is arranged to optically connect the third optical interface (10c) of the first optical splitter-combiner (9) to the first optical input port (6) of the first optical receiver (5); and The eighth semiconductor-based optical waveguide (19h) is arranged to optically connect the sixth optical interface (12c) of the second optical splitter-combiner (11) to the second optical input port (8) of the second optical receiver (7).

4. The PIC (1) according to claim 1, wherein: The first optical receiver (5) of the at least two optical receivers has a first optical input port (6); The second optical receiver (7) of the at least two optical receivers has a second optical input port (8); The first optical splitter-combiner (9) has: The first end (9a) is provided with at least a first optical interface (10a) and a second optical interface (10b); and The second end (9b) is provided with at least a third optical interface (10c). The second optical splitter-combiner (11) has: The third end (11a) is provided with at least a fourth optical interface (12a) and a fifth optical interface (12b); and The fourth end (11b) is provided with at least a sixth optical interface (12c); The InP-based polarization processing unit includes: An InP-based polarization separator (15) has a fourth optical input port (16a), a third optical output port (16b), and a fourth optical output port (16c); and A polarization rotator (17) based on InP, having a fifth optical input port (18a) and a fifth optical output port (18b); and The plurality of semiconductor-based optical waveguides include: A first semiconductor-based optical waveguide (19a) is arranged to optically connect the first fiber-to-chip coupling position (2) of the at least three fiber-to-chip coupling positions to the first optical interface (10a) of the first optical splitter-combiner (9). The second semiconductor-based optical waveguide (19b) is arranged to optically connect the second fiber-to-chip coupling position (3) of the at least three fiber-to-chip coupling positions to the fourth optical input port (16a) of the InP-based polarization separator (15). A third semiconductor-based optical waveguide (19c) is arranged to optically connect the third fiber-to-chip coupling position (4) of the at least three fiber-to-chip coupling positions to the fourth optical interface (12a) of the second optical splitter-combiner (11). A fourth semiconductor-based optical waveguide (19d) is arranged to optically connect the third optical output port (16b) of the InP-based polarization separator (15) to the second optical interface (10b) of the first optical splitter-combiner (9). The fifth semiconductor-based optical waveguide (19e) is arranged to optically connect the fourth optical output port (16c) of the InP-based polarization separator (15) to the fifth optical interface (12b) of the second optical splitter-combiner (11). The sixth semiconductor-based optical waveguide (19f) is arranged to optically connect the third optical interface (10c) of the first optical splitter-combiner (9) to the fifth optical input port (18a) of the InP-based polarization rotator (17). A seventh semiconductor-based optical waveguide (19g) is arranged to optically connect the fifth optical output port (18b) of the InP-based polarization rotator (17) to the first optical input port (6) of the first optical receiver (5); and The eighth semiconductor-based optical waveguide (19h) is arranged to optically connect the sixth optical interface (12c) of the second optical splitter-combiner (11) to the second optical input port (8) of the second optical receiver (7).

5. The PIC (1) according to claim 1, wherein, The at least two optical receivers (5, 7): For coherent optical receiver; or It is configured to recover information from an optical signal encoded using amplitude modulation.

6. The PIC (1) according to claim 1, wherein, Of the at least three fiber-to-chip coupling positions, at least the first fiber-to-chip coupling position (2) and the third fiber-to-chip coupling position (4) are arranged apart by a distance D, the distance D being in the range of 20µm to 1000µm, preferably in the range of 250µm to 500µm.

7. The PIC (1) according to claim 1, wherein, The at least three fiber-to-chip coupling locations (2, 3, 4) are arranged on the same side (20) of the PIC (1).

8. The PIC (1) according to claim 1, wherein, At least one of the at least two optical splitter-combiners (9, 11) is a thermally tunable optical splitter-combiner or an electro-optically tunable optical splitter-combiner.

9. The PIC (1) according to claim 1, wherein, At least one of the at least two optical splitter-combiner (9, 11) is a coupler based on multimode interference (MMI).

10. The PIC (1) according to claim 9, wherein, MMI-based couplers are either thermally tunable MMI-based couplers or electro-optically tunable MMI-based couplers.

11. The PIC (1) according to claim 9, wherein, The MMI-based coupler is configured and arranged as an asymmetric MMI-based coupler.

12. The PIC (1) according to claim 10, wherein, The MMI-based coupler is configured and arranged as an asymmetric MMI-based coupler.

13. The PIC (1) according to claim 1, wherein, At least one of the first semiconductor-based optical waveguide (19a) at the first fiber-to-chip coupling position (2), the second semiconductor-based optical waveguide (19b) at the second fiber-to-chip coupling position (3), and the third semiconductor-based optical waveguide (19c) at the third fiber-to-chip coupling position (4) is provided with a tapered portion (21).

14. The PIC (1) according to claim 1, wherein, At least one of the at least two optical receivers (5, 7), the at least two optical splitter-combiner (9, 11), and the plurality of semiconductor-based optical waveguides (19a-19h) comprise InP-based semiconductor materials.

15. The PIC (1) according to claim 1, wherein, The PIC (1) is a hybrid PIC or a monolithic PIC based on InP.

16. An optoelectronic system (100) comprising the PIC (1) according to claim 1.

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