Multi-wavelength tunable laser arrangement and method for the same

Abstract

A multi-wavelength tunable laser arrangement including an array of semiconductor optical amplifiers, SOAs, each SOA acting as a reflective SOA and provide light of a wavelength, and a photonic integrated circuit, PIC, for receiving the light from each SOA. The PIC includes an interleaver to receive the light from each SOA and multiplex them into an interleaved channel, a high-finesse filter to set a spectral spacing between channels comprised in the interleaved channel, a wide tunable filter to receive the interleaved channel, to set a central wavelength of a super channel and a phase shifter. The multi-wavelength tunable laser arrangement includes a wavelength locker configured to receive the light from at least one of the SOAs and to lock the wavelength of that light, a reflector configured to reflect the light, and a controller. The multi-wavelength tunable laser arrangement efficiently supports the evolution of long-haul transport networks towards 1.6T / 3.2T generation.

Description

[0001] MULTI-WAVELENGTH TUNABLE LASER ARRANGEMENT AND METHOD FOR THE SAME

[0002] TECHNICAL FIELD

[0003] The present disclosure relates generally to the field of semiconductor optical amplifiers; and more specifically, to a multiwavelength tunable laser arrangement and a method for the multi-wavelength tunable laser arrangement.

[0004] BACKGROUND

[0005] The continuous evolution of long-haul transport networks towards the 1.6 terabits per second (1.6T) / 3.2T generation presents significant challenges in the realm of coherent optical transmission systems. With an exponential growth in data throughput witnessed in past decades, there has been a corresponding increase in baud rates to accommodate this surge in demand. The reaching baud rates of 300-400 Gigabaud (GBd) over a single optical channel, as required by the transition to 1.6T / 3.2T network systems, induces formidable challenges for modulators and Analog-to-Digital (A / D) and Digital-to-Analog (D / A) converters. To address this bottleneck, the adoption of super-channel technology alongside mature low-baud-rate components emerges as a promising solution for constructing optical transceivers capable of supporting greater than or equal to 1.6 Tbits / s data rates. This approach leverages the aggregation of multiple wavelengths into a spectral super channel, thereby distributing the data load across multiple lower baud rate channels. However, the successful implementation of such approach hinges on the availability of multi-wavelength solutions for the optical transceivers.

[0006] Currently, certain attempts have been made to support the evolution of long-haul transport networks towards 1.6T / 3.2T generation, such as a conventional tunable multi-wavelength semiconductor laser array based on wavelength division multiplexing is proposed for optical communications. This solution requires an optical transceiver using several tunable lasers and a laser control unit, which synchronously tunes the different optical wavelengths of the tunable lasers. However, the use of several independent lasers presents the disadvantage of requiring the channel spacing to be typically 5 GHz larger than the channel spectrum width to compensate for the + / -2.5 GHz wavelength locker uncertainty. Thus, for a given channel spacing, the spectrum width has to be reduced, resulting in a significant reduction of the baud rate (e.g., 10%), which can be translated into a significant transmission reach reduction (e.g., 20%). In another solution, a multichannel coherent optical transceiver is proposed to support the evolution of long-haul transport networks towards 1.6T / 3.2T generation. This solution is based on a conventional laser array combined to a Semiconductor Optical Amplifier (SO A) array. However, the lasers are independent from each other without a system to lock the channel spacing. This solution also requires the channel spacing to be typically 5 GHz larger than the channel spectrum width to compensate for the + / -2.5 GHz wavelength locker uncertainty, resulting in a significant reduction of the baud rate (e.g., 10%). In a yet another solution, a tunable laser based on switching between a plurality of discrete channels is proposed. However, the size and complexity of an optical device increase with the number of discrete channels used to cover the tunable wavelength range. The optical device is required to select the desired channels among the possible discrete channels and one path of the optical device constitutes one possible discrete channel. Thus, there exists a technical problem of an inefficient multi -wavelength laser source which can support the evolution of long-haul transport networks towards 1.6T / 3.2T generation.

[0007] Therefore, in light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks associated with the conventional multi -wavelength laser source used for optical communication.

[0008] SUMMARY

[0009] The present disclosure provides a multi-wavelength tunable laser arrangement and a method for the multi-wavelength tunable laser arrangement. The present disclosure provides a solution to the existing problem of an inefficient multi-wavelength laser source which can support the evolution of long-haul transport networks towards 1.6T / 3 ,2T generation. An aim of the present disclosure is to provide a solution that overcomes at least partially the problems encountered in prior art, and provide an improved multi-wavelength tunable laser arrangement and an improved method for the multi-wavelength tunable laser arrangement.

[0010] The object of the present disclosure is achieved by the solutions provided in the enclosed independent claims. Advantageous implementations of the present disclosure are further defined in the dependent claims.

[0011] In one aspect, the present disclosure provides a multi-wavelength tunable laser arrangement comprising an array of a plurality of semiconductor optical amplifiers, SOAs, each SOA (SOAi) configured to provide light of a wavelength (A;), and a photonic integrated circuit (PIC) optically connected to the SOA array for receiving the light from each SOA (SOAi) and configured to act as a wavelength-selective reflector, where the PIC comprises an interleaver (Nxl) configured to receive the light from each SOA and multiplex them into an interleaved channel, a high-finesse filter configured to set a spectral spacing between channels comprised in the interleaved channel, a wide tunable filter configured to receive the interleaved channel, to set a central wavelength of a super channel and to select the desired number of channels, and a phase shifter for each SOA configured for phase control, where the multi-wavelength tunable laser arrangement further comprises a wavelength locker configured to receive the light from at least one of the SOAs (SOAi) and to lock the wavelength (A;) of that light, a reflector configured to reflect the light, and a controller configured to control the phase shifter, the interleaver, the wide tunable filter and the high finesse filter.

[0012] The disclosed multi-wavelength tunable laser arrangement efficiently supports the evolution of long-haul transport networks towards 1.6T / 3.2T generation. The disclosed multi-wavelength tunable laser arrangement manifests the capability of delivering multiple wavelengths with locked channel spacing to form a super channel using a single photonic device. The channel spacing is accurately set by the use of the high-finesse filter. The use of the wavelength locker is also advantageous in terms of locking one wavelength, for instance, to the ITU grid, or to a specific value, since the channel spacing is already “locked” by the chip itself (i.e., the multi-wavelength tunable laser arrangement) by use of the high-finesse filter. In the array of the plurality of SOAs, each SOA is used per one wavelength line to maximize the output power per one wavelength line. Moreover, the multiwavelength tunable laser arrangement offers an integrated solution by integrating the array of the plurality of SOAs and the PIC and hence, allows a cost-effective large-scale production. Additionally, the multi-wavelength tunable laser arrangement can be used in optical transceivers for 1.6T / 3 ,2T long haul transmissions to build spectral super channels. The multi -wavelength tunable laser arrangement may be used in data centres based on optical circuit switching. Moreover, the multi-wavelength tunable laser arrangement may be used in any application scenario requiring a tunable laser source with multiple wavelength outputs with locked channel spacing.

[0013] In an implementation form, the high-finesse filter is further configured to set a spectral spacing based on its free spectral range.

[0014] The free spectral range allows a greater flexibility in wavelength selection and wider spacing between spectral lines or channels, which is advantageous for reducing crosstalk resulting in enhancement of overall performance of the multi-wavelength tunable laser arrangement.

[0015] In a further implementation form, each of the SOA is configured to operate as a reflective SOA.

[0016] In a further implementation form, the wavelength locker is configured to receive the light from at least one of the SOAs (SOAi) through an optical connection before the interleaver and where the reflector is arranged in conjunction with the high-finesse filter. The wavelength locker is configured to receive the light from at least one of the SO As through the optical connection before the interleaver, which is advantageous to obtain a simplicity in design of an optical device.

[0017] In a further implementation form, the multi -wavelength tunable laser arrangement further comprises a de-interleaver (IxN) configured to receive the light from the high-finesse filter and to demultiplex the light into individual wavelengths (A,). and where the wavelength locker is configured to receive the light from at least one of the SO As (SOAi) and to receive the light through an optical connection after the de-interleaver (IxN).

[0018] In a further implementation form, the reflector is arranged before the de-interleaver (IxN), wherein the light is optically connected to the de-interleaver through an optical coupler.

[0019] Such configuration is advantageous in terms of providing a variable reflection ratio so that optimization of threshold currents and optical powers can be obtained.

[0020] In a further implementation form, the wavelength locker is configured to receive the light from all of the SOAs (SOAi).

[0021] In a further implementation form, the wavelength locker is configured to receive the light from one of the SOAs (SOAi).

[0022] In another aspect, the present disclosure provides a method for a multi-wavelength tunable laser arrangement, the method comprising interleaving a plurality of lights from an array of SOAs into an interleaved light utilizing an interleaver, set a spectral spacing between channels of the interleaved light utilizing a tunable high-finesse filter, and select a super channel from the interleaved light utilizing a wide tunable filter.

[0023] The method achieves all the advantages and technical effects of the multi-wavelength tunable laser arrangement.

[0024] It is to be appreciated that all the aforementioned implementation forms can be combined.

[0025] It has to be noted that all devices, elements, circuitry, units and means described in the present application couldbe implemented in the software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof. It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.

[0026] Additional aspects, advantages, features and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative implementations construed in conjunction with the appended claims that follow.

[0027] BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those skilled in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers. Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:

[0029] FIG. 1 is a block diagram that illustrates various exemplary components of a multi-wavelength tunable laser arrangement, in accordance with an embodiment of the present disclosure;

[0030] FIG. 2 illustrates a multi-wavelength tunable laser arrangement, in accordance with an embodiment of the present disclosure;

[0031] FIG. 3 illustrates a multi-wavelength tunable laser arrangement, in accordance with another embodiment of the present disclosure;

[0032] FIG. 4 illustrates an alternative representation of the multi -wavelength tunable laser arrangement of FIG. 2, in accordance with another embodiment of the present disclosure;

[0033] FIG. 5 illustrates an alternative representation of the multi -wavelength tunable laser arrangement of FIG. 2, in accordance with yet another embodiment of the present disclosure;

[0034] FIG. 6 illustrates an alternative representation of the multi -wavelength tunable laser arrangement of FIG. 2, in accordance with yet another embodiment of the present disclosure;

[0035] FIG. 7 illustrates an alternative representation of the multi -wavelength tunable laser arrangement of FIG. 3 , in accordance with another embodiment of the present disclosure;

[0036] FIG. 8 illustrates an alternative representation of the multi -wavelength tunable laser arrangement of FIG. 3 , in accordance with yet another embodiment of the present disclosure;

[0037] FIG. 9 illustrates an alternative representation of the multi -wavelength tunable laser arrangement of FIG. 3 , in accordance with yet another embodiment of the present disclosure;

[0038] FIG. 9 A illustrates an alternative representation of the multi -wavelength tunable laser arrangement of FIG. 3, in accordance with yet another embodiment of the present disclosure;

[0039] FIG. 10 illustrates tunability of a multi-wavelength tunable laser source using a wide tunable filter and a high-finesse tunable filter, in accordance with an embodiment of the present disclosure;

[0040] FIG. 11 is a block diagram that illustrates various exemplary components of an optical transceiver, in accordance with an embodiment of the present disclosure; and

[0041] FIG. 12 is a flowchart of a method for a multi -wavelength tunable laser arrangement, in accordance with an embodiment of the present disclosure.

[0042] In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.

[0043] DETAILED DESCRIPTION OF EMBODIMENTS

[0044] The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.

[0045] FIG. 1 is a block diagram that illustrates various exemplary components of a multi-wavelength tunable laser arrangement, in accordance with an embodiment of the present disclosure. With reference to FIG. 1, there is shown a block diagram 100 of a multi -wavelength tunable laser arrangement 102 that comprises an array of a plurality of Semiconductor Optical Amplifiers (SOAs) 104 and a Photonic Integrated Circuit (PIC) 106. The PIC 106 comprises an interleaver 108, a high-finesse filter 110, a wide tunable filter 112 and a phase shifter 114. The multi-wavelength tunable laser arrangement 102 further comprises a wavelength locker 116, a reflector 118 and a controller 120. Each of the components of the multi-wavelength tunable laser arrangement 102, such as the array of the plurality of SOAs 104, the PIC 106, the wavelength locker 116, the reflector 118 and the controller 120 are optically connected with each other. Furthermore, each component of the PIC 106, such as the interleaver 108, the high-finesse filter 110, the wide tunable filter 112 and the phase shifter 114 are optically connected with each other. The PIC 106 further comprises a photodiode 122 for each SOA.

[0046] The multi-wavelength tunable laser arrangement 102 may be referred to as a system or a configuration capable of emitting light at different wavelengths based on a single integrated tunable laser source array. The multi -wavelength tunable laser arrangement 102 has an added functionality of tunability across various wavelengths. The multi-wavelength tunable laser arrangement 102 enables the generation of optical signals comprising multiple wavelengths that can be adjusted or tuned dynamically to specific frequencies within a certain range.

[0047] The array of the plurality of SOAs 104 may include suitable logic, circuitry, interfaces, or code where each SOA (i.e., SOAi) is configured to provide light of a wavelength (A;). Each SOA may be defined as a device that amplifies light based on a semiconductor gain medium. Each SOA from the array of the plurality of SOAs is used as a reflective SOA (RSOA) and one of the facet of each SOA is not anti-reflection coated. The SOAs have a similar structure to Fabry-Perot semiconductor lasers but with anti-reflection coatings on both facets to prevent the SOA to act as a laser cavity. The tilted waveguides can also be used to further reduce the undesirable reflections at both facets. An electric current is externally applied to the SOA and when light enters the SOA, the light is amplified by stimulated emission. Therefore, an optical signal passing through the SOA is said to have an experienced optical gain.

[0048] The PIC 106 may include suitable logic, circuitry, interfaces, or code that is optically connected to the array of the plurality of SOAs 104. The PIC 106 may also be referred to as an integrated optical circuit. The PIC 106 may be defined as a microchip containing two or more photonic components that form a functioning circuit. The PIC 106 may be configured to detect, generate, transport, and process light. The PIC 106 may be configured to utilize photons (or particles of light) as opposed to electrons that are utilized by Electronic Integrated Circuits (EICs). The major difference between the two is that the PIC 106 provides functions for information signals imposed on optical wavelengths typically in the visible spectrum or near infrared (850-1650 nm).

[0049] The interleaver 108 may include suitable logic, circuitry, interfaces, or code that is configured to receive the light from each SOA and multiplex them into an interleaved channel. The interleaver 108 may also be referred to as an optical interleaver. The interleaver 108 may be defined as a passive fibre-optic device used to combine (or multiplex) two or more sets of Dense Wavelength-Division Multiplexing (DWDM) channels into a composite signal stream in an interleaving way. For example, the interleaver 108 may take two multiplexed signals with 100 GHz spacing and interleaves them, creating a denser DWDM signal with channel spaced 50 GHz apart. The interleaver 108 may also be used to demultiplex the denser DWDM signal into odd and even channels.

[0050] The high-finesse filter 110 may be referred to as an optical filter that exhibits a high finesse value. The finesse is a measure of resolution or sharpness of an optical filter, quantifying how effectively the optical filter can separate closely spaced wavelengths of light. A typical high-finesse filter has a narrow bandwidth and can efficiently transmit or reflect light within a specific range of wavelengths while strongly attenuating light outside that range. The high-finesse filter 110 may be used in applications, such as spectroscopy, laser systems, telecommunications, and optical sensing where precise wavelength control is required.

[0051] The wide tunable filter 112 may be referred to as an optical bandpass filter designed to selectively transmit or reflect light within a broad range of wavelengths while offering tunability across the selected range of wavelengths. Unlike fixed-bandwidth filters, which are limited to a specific wavelength range, the wide tunable filter 112 can be adjusted to operate over a much broader spectrum typically spanning tens or hundreds of nanometres. The wide tunable filter 112 is commonly used in applications where the spectral characteristics of an incoming light may vary or required to be precisely controlled. For example, in optical communications, the wide tunable filter 112 can be employed to dynamically adjust the wavelength channels in wavelength division multiplexing (WDM) systems, enabling flexible allocation of bandwidth and efficient utilization of optical fibre capacity.

[0052] The wavelength locker 116 may include suitable logic, circuitry, interfaces, or code that is configured to receive the light from at least one of the SOAs (SOAi) from the array of the plurality of SOAs 104 and to lock the wavelength (A;) of that light. Alternatively stated, the wavelength locker 116 may be configured to serve as the guardian of precision in optical communication systems. The operation of the wavelength locker 116 hinges on a feedback loop that continuously monitors the emitted wavelength and makes adjustments as required. The use of the wavelength locker 116 ensures that the laser (or an optical amplification device) operates at its specified wavelength, irrespective of environmental conditions or operational variations.

[0053] In operation, the multi -wavelength tunable laser arrangement 102 comprises the array of the plurality of semiconductor optical amplifiers, SOAs, 104 each SOA (SOAi) configured to provide light of a wavelength (A;), and the photonic integrated circuit (PIC) 106 optically connected to the SOA array for receiving the light from each SOA (SOAi) and configured to act as a wavelength-selective reflector. The multi-wavelength tunable laser arrangement 102 is capable of providing N wavelengths to build a spectral super channel, which further supports the evolution of long-haul transport networks towards 1.6T / 3.2T generation. In an example, the multi -wavelength tunable laser arrangement 102 may be configured to generate 2 wavelengths (e.g., N=2, i.e., 22.) for 1.6T network systems. In another example, the multi-wavelength tunable laser arrangement 102 may be configured to generate 4 wavelengths (e.g., N=4, i.e., 42) for 3 ,2T network systems with 200GB. The spectral super channel composed of N wavelengths is made tunable over required optical bands by use of tunable filters. The multi-wavelength tunable laser arrangement 102 comprises the array of the plurality of SOAs 104 coupled to the PIC 106 with the tunable filters. Alternatively, the array of the plurality of SOAs 104 is hybrid integrated to the PIC 106. The array of the plurality of SOAs 104 (may also be referred to as a SOA array) and the tunable filters allow to provide a gain medium covering C+L bands or other bands as well, with a single chip and to use one SOA per wavelength line to maximize output power per wavelength.

[0054] In accordance with an embodiment, the multi -wavelength tunable laser arrangement 102 is of an external cavity configuration. The multi -wavelength tunable laser arrangement 102 (or an integrated tunable laser source) is based on the external cavity configuration comprising the array of the plurality of SOAs 104 and the PIC 106.

[0055] In accordance with an embodiment, each of the SOA is configured to operate as a reflective SOA. The array of the plurality of SOAs 104 is used as an array of reflective SOAs (RSOAs) by R% (e.g., 30%) coating on left facet of each SOA. Alternatively, each SOA in the array of reflective SOAs has anti-reflection coating on right facet (e.g., the SOA array facet couplet to the PIC 106). The rear facet of each SOA in the array of the plurality of SOAs 104 is high-reflectivity facet if the output light of the multi -wavelength tunable laser arrangement 102 is collected from the PIC 106 facet. In another scenario, if the output light of the multi-wavelength tunable laser arrangement 102 is collected from rear facet of the array of the plurality of SOAs 104, the rear facet can be either left as cleaved (no coating -R —30%) or coated to obtain a specific reflection ratio. The light coupled out of the multi-wavelength tunable laser arrangement 102 depends on the specific reflection ratio. Each SOA is configured to operate as RSOA in different implementation scenarios of the multi-wavelength tunable laser arrangement 102, described and shown, for example, inFIGs. 2, 3, 4, 5, 6, 7, 8, 9, and 9A.

[0056] The PIC 106 comprises the interleaver (Nxl) 108 configured to receive the light from each SOA and multiplex them into an interleaved channel, the high-finesse filter 110 configured to set a spectral spacing between channels comprised in the interleaved channel, the wide tunable filter 112 configured to receive the interleaved channel, to set a central wavelength of a super channel and to select the desired number of channels, and the phase shifter 114 for each SOA configured for phase control. In an exemplary scenario, the interleaver 108 (e.g., 4x1) is configured to receive the light of different wavelengths from each SO A (e.g., 4 SO As) in the array of the plurality of SO As 104 and multiplex the received wavelengths into the interleaved channel. Typically, the interleaved channel refers to a method of organizing multiple optical signals (or optical channels) in a sequential and alternating manner within a broader transmission band or spectrum The high-finesse filter 110 is used to accurately set the spectral spacing (e.g., 150-200 GHz or any other value) between the multiple channels comprised in the interleaved channel. The selection of the desired spectral super channel over the tunable range (e.g., 100 nm) is allowed by the wide tunable filter 112. Typically, a spectral super channel involves aggregating multiple optical channels or wavelengths within an optical spectrum. The spectral super channel utilizes different wavelengths orfrequency channels within same optical fibre. The spectral super channel can be obtained by multiplexing multiple wavelength-division multiplexed (WDM) channels or frequency-division multiplexed (FDM) channels. The spectral super channel offers enhanced data capacity by efficiently utilizing the available optical spectrum and particularly, suitable for optical communication systems having ample spectral bandwidth. The spectral super channel offers enhanced data capacity without requiring an additional optical spectrum, particularly useful in scenarios where the available spectral bandwidth is limited. The PIC 106 further comprises the phase shifter 114 configured to control the phase of light of the wavelength (i.e., A;) provided by each SOAinthe array of the plurality of SOAs 104.

[0057] In accordance with an embodiment, the high-finesse filter 110 is further configured to set a spectral spacing based on its free spectral range. Typically, the free spectral range refers to the range of wavelengths or frequencies over which an optical device (e.g., the multi-wavelength tunable laser arrangement 102) can operate without encountering interference between the adjacent spectral lines. The free spectral range allows a greater flexibility in wavelength selection and wider spacing between spectral lines or channels, which is advantageous to enhance the overall performance of the multi-wavelength tunable laser arrangement 102.

[0058] In accordance with an embodiment, the interleaver 108 is further configured to receive the light from each SOA and multiplex them at an initial spacing. The interleaver 108 is configured to receive the light (or optical signal) from each SOA of the array of the plurality of SO As 104 and combines the received the optical signals into the interleaved channel, where each optical signal has the initial spectral spacing from another optical signal. The initial spectral spacing may be later modified by the high- finesse filter 110. The interleaver 108 may be configured either to multiplex the received optical signals, shown and described in detail, for example, in FIG. 2 or de-multiplex the received optical signals and hence, may be referred to as a de-interleaver, shown and described in detail, for example, in FIG. 3.

[0059] The multi -wavelength tunable laser arrangement 102 further comprises the wavelength locker 116 configured to receive the light from at least one of the SOAs (SOAi) and to lock the wavelength (A;) of that light, the reflector 118 configured to reflect the light, and the controller 120 configured to control the phase shifter 114, the interleaver 108, the wide tunable filter 112 and the high-finesse filter 110. The wavelength locker 116 is configured to lock the multiple wavelengths emitted by the array of the plurality of SOAs 104. In an implementation scenario, the wavelength locker 116 is configured to lock the multiple wavelengths on the International Telecommunication Union (ITU) grid using a dedicated control algorithm. The controller 120 is configured to execute the dedicated control algorithm. The reflector 118 is configured to reflect the light received from each SOA of the array of the plurality of SOAs 104. In an implementation scenario, the reflector 118 may be used in conjunction with the high-finesse filter 110 as shown and described, for example, in FIGs. 2 and 4. In another implementation scenario, the reflector 118 may be used in conjunction with an optical coupler as shown and described, for example, in FIGs. 3, 7, 8 and 9.

[0060] In accordance with an embodiment, the PIC 106 further comprises the photodiode 122 for each SOA, the photodiode 122 being configured for monitoring of the SOA by the controller 120. The photodiode 122 is used as monitoring element for monitoring of each SOA of the array of the plurality of SOAs 104. In accordance with an embodiment, the SOA is optically connected to the PIC 106 by being comprised in the PIC 106. The array of the plurality of SOAs 104 and the PIC 106 are optically connected to each other, shown and described, for example, in FIGs. 2, 3, 4, 5, 6, 7, 8, and 9.

[0061] In accordance with an embodiment, the SOA is optically connected to the PIC 106 by being comprised in the PIC 106 utilizing hybrid integration. In an implementation scenario, the array of the plurality of SOAs 104 is hybrid integrated to the PIC 106 comprising the high- finesse filter 110 and the wide tunable filter 112.

[0062] In accordance with an embodiment, the PIC 106 further comprises the wavelength locker 116. In an implementation scenario, the wavelength locker 116 is integrated to the PIC 106, as shown and described, for example, in FIGs. 2, 3, 5, and 8.

[0063] In accordance with an embodiment, the PIC 106 is optically connected to the wavelength locker 116. In an implementation scenario, the wavelength locker 116 is not integrated to the PIC 106 but has an optical connection with the PIC 106, as shown and described, for example, in FIGs. 4, 6, 7 and 9.

[0064] Thus, the multi-wavelength tunable laser arrangement 102 manifests the capability of delivering multiple wavelengths with locked channel spacing to form a super channel using a single photonic device. The channel spacing is accurately set by the use of the high-finesse filter 110. The use of the wavelength locker 116 is also advantageous in terms of locking one wavelength for instance, to the ITU grid, or to a specific value, since the channel spacing is already “locked” by the chip itself (i.e., the multi -wavelength tunable laser arrangement 102) by use of the high-finesse filter 110. In the array of the plurality of SOAs 104, each SOA is used per one wavelength line to maximize the output power per one wavelength line. Moreover, the multiwavelength tunable laser arrangement 102 offers an integrated solution by integrating the array of the plurality of SOAs 104 and the PIC 106 and hence, allows a cost-effective large-scale production. Additionally, the multi-wavelength tunable laser arrangement 102 can be used in optical transceivers for 1.6T / 3.2T long haul transmissions to build spectral super channels. The multi-wavelength tunable laser arrangement 102 may be used in data centres based on optical circuit switching. Moreover, the multi -wavelength tunable laser arrangement 102 may be used in any application scenario requiring a tunable laser source with multiple wavelength outputs with locked channel spacing. The number of SOAs, the free spectral range of the high-finesse filter 110 and the transfer function of the wide tunable filter 112 can be designed to achieve the desired number of channels and channel spacing.

[0065] FIG. 2 illustrates a multi-wavelength tunable laser arrangement, in accordance with an embodiment of the present disclosure. FIG. 2 is described in conjunction with elements from FIG. 1. With reference to FIG. 2, there is shown a multi-wavelength tunable laser arrangement 202. There is further shown an optical connection 204.

[0066] The multi-wavelength tunable laser arrangement 202 corresponds to the multi-wavelength tunable laser arrangement 102 (of FIG. 1). In the multi-wavelength tunable laser arrangement 202, there is shown the array of the plurality of SOAs 104, which is composed of N SOAs (N being the number of targeted wavelengths: e.g., N=4 as shown in FIG. 2). The array of the plurality of SOAs 104 (or the SOA array) is made up of Indium-phosphide (InP) semiconductor material. Moreover, left facet of each SOA in the array of the plurality of SOAs 104 has R% (e.g., 30%) coating of reflective material. There is further shown the PIC 106 which is made up of Silicon Nitride (SiN) or Silicon-On-Insulator (SOI). The PIC 106 comprises the interleaver 108, the wide tunable filter 112, the high-finesse filter 110, the phase shifter 114 and the reflector 118. The interleaver 108 is used as a multiplexer (Nxl) for multiplexing N optical signals (i.e., N = 4) received by the PIC 106 from the array of the plurality of SOAs 104. The multiplexing of N = 4 optical signals results in a quad interleaved channel with a coarse spacing of, for example, 200GHz. The wide tunable filter 112 is used to select the super channel and the high-finesse filter 110 is used to accurately set the channel spacing in the selected super channel. The wide tunable filter 112 is used to achieve the tunability of the quad channel (e.g., 700GHz) and the high-finesse filter 110 is used to lock the quad channel at, for example, 200GHz + / - 0.5GHz. The reflector 118 (or a back reflector) is used in conjunction with the high-finesse filter 110. The phase shifter 114 is used as a control element to control the phase of each optical signal emitted by each SOA of the array of the plurality of SO As 104. As shown in FIG. 2, the photodiode 122 is comprised by the SOA array for monitoring each SOA of the array of the plurality of SOAs 104. The wavelength locker 116 is used to lock the multi-wavelength source on the ITU grid using a dedicated control algorithm. The dedicated control algorithm is executed by the controller 120. The controller 120 is configured to control the interleaver 108, the wide tunable filter 112, the high-finesse filter 110, and the phase shifter 114. In FIG. 2, the output of the multi-wavelength tunable laser arrangement 202 is taken from left facet of the SOA array (i.e., the array of the plurality of SOAs 104).

[0067] In accordance with an embodiment, the wavelength locker 116 is configured to receive the light from at least one of the SOAs (SOAi) through the optical connection 204 before the interleaver 108 and wherein the reflector 118 is arranged in conjunction with the high-finesse filter 110. As shown in FIG. 2, the wavelength locker 116 is configured to receive the light (or the optical signal) from the at least one SOA of the array of the plurality of SOAs 104 through the optical connection 204. Moreover, in the multi-wavelength tunable laser arrangement 202, the reflector 118 is used in conjunction with the high-finesse filter 110.

[0068] The multi-wavelength tunable laser arrangement 202 manifests the ability to integrate all required optical functions into a single chip. In multi-wavelength tunable laser arrangement 202, the wavelength locker 116 is used as a part of the integrated device (i.e., the multi-wavelength tunable laser arrangement 202). Furthermore, the wavelength locker 116 is configured to use only one of the N signals as an input thereby, reducing the complexity and size of the integrated device. Another advantage of the multi -wavelength tunable laser arrangement 202 is that the output is collected from left facet of the SOA array (i.e., the array of the plurality of SOAs 104) hence, reducing the number of required optical functions.

[0069] FIG. 3 illustrates a multi-wavelength tunable laser arrangement, in accordance with another embodiment of the present disclosure. FIG. 3 is described in conjunction with elements from FIGs. 1 and 2. With reference to FIG. 3, there is shown a multi-wavelength tunable laser arrangement 302. There is further shown a de-interleaver 304, an optical coupler 306 and an optical connection 308.

[0070] The multi-wavelength tunable laser arrangement 302 is similar to the multi -wavelength tunable laser arrangement 202 (of FIG. 2) except that the multi-wavelength tunable laser arrangement 302 is configured to use of the de-interleaver 304, the optical coupler 306 and the way the output is collected from right facet of the PIC 106.

[0071] In accordance with an embodiment, the multi-wavelength tunable laser arrangement 302 further comprises the de-interleaver (e.g., IxN) 304 configured to receive the light from the high-finesse filter 110 and to demultiplex the light into individual wavelengths (A;), and where the wavelength locker 116 is configured to receive the light from at least one of the SOAs (SOAi) and to receive the light through the optical connection 308 after the de-interleaver (IxN) 304. The de-interleaver 304 is used as a demultiplexer to demultiplex the N signals at the output of the PIC 106. The wavelength locker 116 is configured to receive the light after demultiplexing through the optical connection 308. The output of the multi-wavelength tunable laser arrangement 302 is collected from the right facet of the PIC 106 whereas, the left facet of each SOA in the array of the plurality of SOAs 104 is used as a black reflector (or high reflectivity coated facet). In another implementation scenario, the wavelength locker 116 may be configured to receive the light from at least one of the SOAs (SOAi) through an optical connection before the interleaver (Nxl) 108, as shown and described, for example, in FIG. 9A.

[0072] In accordance with an embodiment, the reflector 118 is arranged before the de-interleaver 304 (IxN), wherein the light is optically connected to the de-interleaver 304 through the optical coupler 306. In the multi-wavelength tunable laser arrangement 302, the reflector 118 is used in conjunction with the optical coupler 306 instead of the high-finesse filter 110. The multi-wavelength tunable laser arrangement 302 manifests all the advantages offered by the multi-wavelength tunable laser arrangement 202 in addition to one more advantageous feature. The output of the multi-wavelength tunable laser arrangement 302 is collected from the right facet of the PIC 106 using the de-interleaver 304 and the optical coupler 306. Such configuration is advantageous over the multi-wavelength tunable laser arrangement 202 (where a fixed reflection ratio is set by the facet coating of the SOA array) of a possible variable reflection ratio so that the threshold currents and the optical powers can be optimized.

[0073] FIG. 4 illustrates an alternative representation of the multi -wavelength tunable laser arrangement of FIG. 2, in accordance with another embodiment of the present disclosure. FIG. 4 is described in conjunction with elements from FIGs. 1, 2 and 3. With reference to FIG. 4, there is shown a multi -wavelength tunable laser arrangement 402.

[0074] The multi -wavelength tunable laser arrangement 402 corresponds to the multi-wavelength tunable laser arrangement 202 (of FIG. 2). Alternatively stated, the multi-wavelength tunable laser arrangement 402 is an alternative representation of the multiwavelength tunable laser arrangement 202. In the multi-wavelength tunable laser arrangement 402, the wavelength locker 116 is not integrated to the PIC 106. Although, in the multi-wavelength tunable laser arrangement 202, the wavelength locker 116 is integrated to the PIC 106.

[0075] In accordance with an embodiment, the wavelength locker 116 is configured to receive the light from one of the SO As (SOAi). In the multi -wavelength tunable laser arrangement 402, the wavelength locker 116 is configured to receive the light from one of the SOAs of the array of the plurality of SOAs 104.

[0076] FIG. 5 illustrates an alternative representation of the multi -wavelength tunable laser arrangement of FIG. 2, in accordance with yet another embodiment of the present disclosure. FIG. 5 is described in conjunction with elements from FIGs. 1, 2, 3 and 4. With reference to FIG. 5, there is shown a multi-wavelength tunable laser arrangement 502.

[0077] The multi -wavelength tunable laser arrangement 502 corresponds to the multi-wavelength tunable laser arrangement 202 (of FIG. 2). Alternatively stated, the multi-wavelength tunable laser arrangement 502 is an alternative representation of the multiwavelength tunable laser arrangement 202. In the multi-wavelength tunable laser arrangement 502, the wavelength locker 116 is integrated to the PIC 106 and configured to use all the four wavelengths as inputs.

[0078] In accordance with an embodiment, the reflector 118 comprises one reflector for each light which are arranged after the deinterleaver (IxN) 304. In the multi-wavelength tunable laser arrangement 502, the reflector 118 comprising one reflector for each light is arranged after the de-interleaver (IxN) 304.

[0079] In accordance with an embodiment, the wavelength locker 116 is configured to receive the light from all of the SOAs (SOAi). In the multi-wavelength tunable laser arrangement 502, the wavelength locker 116 is configured to receive the light from all of the SOAs of the array of the plurality of SOAs 104 through the reflector 118.

[0080] FIG. 6 illustrates an alternative representation of the multi -wavelength tunable laser arrangement of FIG. 2, in accordance with yet another embodiment of the present disclosure. FIG. 6 is described in conjunction with elements from FIGs. 1, 2, 3, 4 and 5. With reference to FIG. 6, there is shown a multi-wavelength tunable laser arrangement 602.

[0081] The multi -wavelength tunable laser arrangement 602 corresponds to the multi-wavelength tunable laser arrangement 202 (of FIG. 2). Alternatively stated, the multi-wavelength tunable laser arrangement 602 is an alternative representation of the multiwavelength tunable laser arrangement 202. In the multi-wavelength tunable laser arrangement 602, the wavelength locker 116 is not integrated to the PIC 106 and configured to use all the four wavelengths as inputs. In the multi-wavelength tunable laser arrangement 602, the reflector 118 comprises one reflector for each light and is arranged after the de-interleaver (IxN) 304. Additionally, in the multi-wavelength tunable laser arrangement 602, the wavelength locker 116 is configured to receive the light from all of the SO As of the array of the plurality of SO As 104 through the de-interleaver (IxN) 304 and the reflector 118.

[0082] FIG. 7 illustrates an alternative representation of the multi -wavelength tunable laser arrangement of FIG. 3 , in accordance with another embodiment of the present disclosure. FIG. 7 is described in conjunction with elements from FIGs. 1, 2, 3, 4, 5 and 6. With reference to FIG. 7, there is shown a multi-wavelength tunable laser arrangement 702.

[0083] The multi-wavelength tunable laser arrangement 702 corresponds to the multi-wavelength tunable laser arrangement 302 (of FIG. 3). Alternatively stated, the multi-wavelength tunable laser arrangement 702 is an alternative representation of the multiwavelength tunable laser arrangement 302. In the multi-wavelength tunable laser arrangement 702, the wavelength locker 116 is not integrated to the PIC 106. Although, in the multi-wavelength tunable laser arrangement 302, the wavelength locker 116 is integrated to the PIC 106. In the multi-wavelength tunable laser arrangement 702, the wavelength locker 116 is configured to receive the light from one of the SOAs of the array of the plurality of SO As 104.

[0084] FIG. 8 illustrates an alternative representation of the multi -wavelength tunable laser arrangement of FIG. 2, in accordance with yet another embodiment of the present disclosure. FIG. 5 is described in conjunction with elements from FIGs. 1, 2, 3, 4, 5, 6 and 7. With reference to FIG. 8, there is shown a multi-wavelength tunable laser arrangement 802.

[0085] The multi -wavelength tunable laser arrangement 802 corresponds to the multi-wavelength tunable laser arrangement 302 (of FIG. 3). Alternatively stated, the multi-wavelength tunable laser arrangement 802 is an alternative representation of the multiwavelength tunable laser arrangement 302. In the multi-wavelength tunable laser arrangement 802, the wavelength locker 116 is integrated to the PIC 106 and configured to use all the four wavelengths as inputs. In the multi-wavelength tunable laser arrangement 802, the wavelength locker 116 is configured to receive the light from all of the SOAs of the array of the plurality of SOAs 104 through the de-interleaver (IxN) 304.

[0086] FIG. 9 illustrates an alternative representation of the multi-wavelength tunable laser arrangement of FIG. 3, in accordance with yet another embodiment of the present disclosure. FIG. 9 is described in conjunction with elements from FIGs. 1, 2, 3, 4, 5, 6, 7 and 8. With reference to FIG. 9, there is shown a multi-wavelength tunable laser arrangement 902.

[0087] The multi -wavelength tunable laser arrangement 902 corresponds to the multi-wavelength tunable laser arrangement 302 (of FIG. 3). Alternatively stated, the multi-wavelength tunable laser arrangement 902 is an alternative representation of the multiwavelength tunable laser arrangement 302. In the multi-wavelength tunable laser arrangement 902, the wavelength locker 116 is not integrated to the PIC 106 and configured to use all the four wavelengths as inputs. In the multi-wavelength tunable laser arrangement 902, the wavelength locker 116 is configured to receive the light from all of the SOAs of the array of the plurality of SOAs 104 through the de-interleaver (IxN) 304.

[0088] FIG. 9 A illustrates an alternative representation of the multi -wavelength tunable laser arrangement of FIG. 3, in accordance with yet another embodiment of the present disclosure. FIG. 9 A is described in conjunction with elements from FIGs. 1, 2, 3, 4, 5, 6, 7, 8 and 9. With reference to FIG. 9A, there is shown a multi-wavelength tunable laser arrangement 902A.

[0089] The multi-wavelength tunable laser arrangement 902A corresponds to the multi-wavelength tunable laser arrangement 302 (of FIG. 3). Alternatively stated, the multi-wavelength tunable laser arrangement 902A is an alternative representation of the multiwavelength tunable laser arrangement 302. The multi -wavelength tunable laser arrangement 902 A comprises the de-interleaver (IxN) configured to receive the light from the high-finesse filter 110 and to demultiplex the light into individual wavelengths (A;), and the wavelength locker 116 is configured to receive the light from at least one of the SOAs (SOAi) through an optical connection 904 before the interleaver 108. FIG. 10 illustrates tunability of a multi-wavelength tunable laser source using a wide tunable filter and a high-finesse tunable filter, in accordance with an embodiment of the present disclosure. FIG. 10 is described in conjunction with elements from FIGs. 1 to 9 and FIG. A. With reference to FIG. 10, there is shown an illustration 1000 of tunability of a multi-wavelength tunable laser source (e.g., the multi-wavelength tunable laser arrangement 202) using the wide tunable filter 112 and the high-finesse filter 110.

[0090] The high-finesse filter 110 is used to accurately set the channel spacing (e.g., 150-200 GHz or any other suitable value) between various channels comprised in an interleaved channel. The wide tunable filter 112 is used to select the desired super channel (either spectral super channel or spatial super channel) over the tunable range (e.g., lOOnm). The SOA gain structure and the tunable filters (i.e., the high-finesse filter 110 and the wide tunable filter 112) allow to cover C+L bands or other bands as well, using a single integrated circuit. In the illustration 1000, a spectral super channel 1002 is formed using four different wavelengths or frequencies. The high-finesse filter 110 is used to accurately set the channel spacing in the spectral super channel 1002 and the wide tunable filter 112 is used to set a central wavelength of the spectral super channel 1002.

[0091] FIG. 11 is a block diagram that illustrates various exemplary components of an optical transceiver, in accordance with an embodiment of the present disclosure. FIG. 11 is described in conjunction with elements from FIGs. 1 to 10 including FIG. 9A. With reference to FIG. 11, there is shown a block diagram 1100 of an optical transceiver 1102 that includes a transmitting unit 1104 and a receiving unit 1106. The transmitting unit 1104 and the receiving unit 1106 collectively includes an Application Specific Integrated Circuit (ASIC) joint Optical Digital Signal Processor (oDSP) 1108. The transmitting unit 1104 further includes a digital-to-analog converter (DAC) 1110, an optical driver 1112 a modulator 1114 and an interleaver 1116. The receiving unit 1106 further includes a de-interleaver 1118, a demodulator 1120, an optical transimpedance amplifier (TIA) 1122, an analog-to-digital converter (ADC) 1124. There is further shown a multi-wavelength tunable laser arrangement 1126 between the modulator 1114 and the demodulator 1120.

[0092] The optical transceiver 1102 enables an efficient utilization of available spectral bandwidth by use of the multi-wavelength tunable laser arrangement 1126 and provides a high amplification gain required for high data rate optical communication systems, for example, 1.6T / 3.2T network systems. The multi -wavelength tunable laser arrangement 1126 corresponds to any of the multi-wavelength tunable laser arrangement 202, 302, 402, 502, 602, 702, 802, and 902 of FIGs. 2 to 9, respectively. The multi-wavelength tunable laser arrangement 1126 includes the optical transmission over a quad channel.

[0093] The transmitting unit 1104 may also be referred to as a transmitting device or a transmitter. Examples of the transmitting unit 1104 may include, but not limited to, a broad band monolithic integrated circuit, a broad band driver amplifier, a customized hardware for the high data rate optical communication system, or any other portable or non-portable optical device.

[0094] The ASIC joint oDSP 1108 may include suitable logic, circuitry, and / or interfaces that is configured to perform signal processing. The ASIC joint oDSP 1108 is used to perform computations on optical and digital signals. Examples of the ASIC joint oDSP 1108 may include, but is not limited to, a general-purpose digital signal processor or a specific -purpose digital signal processor.

[0095] The DAC 1110 may include suitable logic, circuitry, and / or interfaces that is configured to convert the signals from digital domain to analog domain. The DAC 1110 further communicates the analog signal to the optical driver 1112 for amplification.

[0096] The optical driver 1112 may include suitable logic, circuitry, and / or interfaces that is configured to provide sufficient signal amplification as required to drive the modulator 1114. The optical driver 1112 is a broadband or a high bandwidth amplifier which can provide high data rate and high gain as well.

[0097] The modulator 1114 (e.g. an optical modulator) may include suitable logic, circuitry, and / or interfaces that is configured to modulate a beam of light (e.g. a laser beam). Examples of the modulator 1114 may include, but is not limited to, an amplitude modulator, phase modulator, polarization modulator, spatial light modulator and many alike. The interleaver 1116 is configured to multiplex multiple optical channels into an interleaved channel. For example, in the optical transceiver 1102, four optical channels are used and therefore, 4x1 interleaver is used to multiplex four optical channels into an interleaved channel and the optical transmission is carried out on the interleaved channel.

[0098] The receiving unit 1106 may also be referred to as a receiving device or a receiver. Examples of the receiving unit 1106 may include, but is not limited to, a broad band monolithic integrated circuit, a broad band transimpedance amplifier (TIA), a customized hardware for the high data rate optical communication system, or any other portable or non-portable optical device.

[0099] The de-interleaver 1118 is configured to de-multiplex the interleaved channel into individual channels.

[0100] The demodulator 1120 is configured to demodulate the received signal.

[0101] The optical TIA 1122 may include suitable logic, circuitry, and / or interfaces that is configured to have various amplification stages and each of them with high bandwidth in order to avoid the degradation of sensitivity of the receiving unit 1106 due to a reduced gain.

[0102] The ADC 1124 is configured to perform the signal conversion from analog domain to digital domain for further processing.

[0103] FIG. 12 is a flowchart of a method for a multi-wavelength tunable laser arrangement, in accordance with an embodiment of the present disclosure. FIG. 12 is described in conjunction with elements from FIGs. 1 to 11 including FIG. 9A. With reference to FIG. 12, there is shown a method 1200 for a multi-wavelength tunable laser arrangement. The method 1200 includes steps 1202 to 1206. The multi -wavelength tunable laser arrangement 102 (of FIG. 1) is configured to execute the method 1200.

[0104] There is provided the method 1200 for the multi-wavelength tunable laser arrangement 102.

[0105] At step 1202, the method 1200 comprises interleaving a plurality of lights from an array of SOAs into an interleaved light utilizing an interleaver. The plurality of lights received from each SOA of the array of SOAs (i.e., the array of the plurality of SOAs 104) is multiplexed into the interleaved light using the interleaver 108.

[0106] At step 1204, the method 1200 further comprises set a spectral spacing between channels of the interleaved light utilizing a tunable high-finesse filter. For example, the high-finesse filter 110 is used to accurately set the spectral spacing (e.g., 150-200 GHz or any other value) between the multiple channels comprised in the interleaved light (or the interleaved channel), have been described in detail, for example, in FIG. 1.

[0107] At step 1206, the method 1200 further comprises select a super channel from the interleaved light utilizing a wide tunable filter. The selection of the desired spectral super channel from the interleaved light over the tunable range (e.g., 100 run) is performed by use of the wide tunable filter 112.

[0108] The steps 1202 to 1206 are only illustrative and other alternatives can also be provided where one or more steps are added, one or more steps are removed, or one or more steps are provided in a different sequence without departing from the scope of the claims herein.

[0109] In an aspect, the present disclosure provides a computer program product comprising program instructions for performing the method 1200, when executed by one or more multi-wavelength tunable laser arrangement 102. In another aspect, the present disclosure provides a computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the method 1200 for the multi -wavelength tunable laser arrangement 102. Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as "including", "comprising", "incorporating", "have", "is" used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural. The word "exemplary" is used herein to mean "serving as an example, instance or illustration". Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and / or to exclude the incorporation of features from other embodiments. The word "optionally" is used herein to mean "is provided in some embodiments and not provided in other embodiments". It is appreciated that certain features of the present disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the present disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable combination or as suitable in any other described embodiment of the disclosure.

Claims

CLAIMS2. The multi-wavelength tunable laser arrangement (102) according to claim 1, wherein the high-finesse filter (110) is further configured to set a spectral spacing based on its free spectral range.

3. The multi-wavelength tunable laser arrangement (102) according to claim 1 or 2, wherein the multi -wavelength tunable laser arrangement (102) is of an external cavity configuration.

4. The multi-wavelength tunable laser arrangement (102) according to claim 1 or 2, wherein each of the SOA is configured to operate as a reflective SOA.

5. The multi-wavelength tunable laser arrangement (102) according to any of claims 1 to 4, wherein the wavelength locker ( 116) is configured to receive the light from at least one of the SO As, SOAi, through an optical connection before the interleaver (108) and wherein the reflector (118) is arranged in conjunction with the high-finesse filter (110).

7. The multi-wavelength tunable laser arrangement (102) according to claim 6, wherein the reflector (118) comprises one reflector for each light which are arranged after the de-interleaver (304).

8. The multi-wavelength tunable laser arrangement (102) according to claim 6, wherein the reflector (118) is arranged before the de-interleaver (304), wherein the light is optically connected to the de-interleaver (304) through an optical coupler (306).

9. The multi-wavelength tunable laser arrangement (102) according to any of claims 1 to 8, wherein the wavelength locker (116) is configured to receive the light from all of the SOAs, SOAi.

10. The multi-wavelength tunable laser arrangement (102) according to any of claims 1 to 8, wherein the wavelength locker (116) is configured to receive the light from one of the SOAs, SOAi.

11. The multi-wavelength tunable laser arrangement (102) according to any preceding claim, wherein the interleaver (108) is further configured to receive the light from each SOA and multiplex them at an initial spacing.

12. The multi -wavelength tunable laser arrangement (102) according to any preceding claim, wherein the PIC (106) further comprises a photodiode (122) for each SOA, the photodiode (122) being configured for monitoring of the SOA by the controller (120).

13. The multi -wavelength tunable laser arrangement (102) according to any preceding claim, wherein the SOA is optically connected to the PIC (106) by being comprised in the PIC (106).

14. The multi-wavelength tunable laser arrangement (102) according to claim 13, wherein the SOA is optically connected to the PIC (106) by being comprised in the PIC (106) utilizing hybrid integration.

15. The multi -wavelength tunable laser arrangement (102) according to any preceding claim, wherein the PIC (106) further comprises the wavelength locker (116).

16. The multi-wavelength tunable laser arrangement (102) according to any of claims 1 to 14, wherein the PIC (106) is optically connected to the wavelength locker (116).

17. A method (1200) for a multi -wavelength tunable laser arrangement (102) the method (1200) comprising interleaving a plurality of lights from an array of SOAs into an interleaved light utilizing an interleaver (108), set a spectral spacing between channels of the interleaved light utilizing a high-finesse filter (110), and select a super channel from the interleaved light utilizing a wide tunable filter (112).

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