On-site calibration of laser transmitters

Abstract

A method (400) for field calibration of a laser transmitter includes receiving a downstream connection (310) from an optical line terminal (OLT) (120) at an optical network unit (ONU) (140), wherein the ONU includes a distributed Bragg reflector (DBR) laser (200). The method further includes attempting to establish an upstream connection (320) between the ONU and the OLT. When the ONU establishes the upstream connection to the OLT, the method further includes receiving a message (312) at the ONU to initiate calibration of the ONU, wherein the message is generated to indicate that the DBR laser is operating outside of an operational state. The method further includes tuning the DBR laser to the operational state by the ONU by adjusting an injection current (212) of the DBR laser.

Description

Technical Field

[0001] The present disclosure relates to in-situ calibration of laser transmitters. Background Art

[0002] Optical fiber communication is an emerging method of transmitting information from a source (transmitter) to a destination (receiver) using optical fiber as a communication channel. Wavelength division multiplexing passive optical network (WDM-PON) is an optical technology for access and backhaul networks. WDM-PON uses multiple different wavelengths on a physical point-to-multipoint optical fiber infrastructure containing passive optical components. Using different wavelengths allows the separation of services within the same physical optical fiber. The result is a network that provides logical point-to-point connections through a physical point-to-multipoint network topology. WDM-PON allows operators to deliver high bandwidth to multiple endpoints over long distances. PON typically includes an optical line terminal (OLT) located at a service provider central office (e.g., a hub), a remote node connected to the central office by a feeder fiber, and many optical network units (ONUs) near end users (e.g., optical network terminals (ONTs)).

[0003] The ONU typically includes a laser to generate an optical signal transmitted to the OLT. The ONU laser may be a distributed Bragg reflector (DBR) laser. A distributed Bragg reflector laser (DBR) is a stable, low-noise, single-frequency laser diode. The DBR laser structure is manufactured with surface features that define a monolithic, single-mode ridge waveguide that runs throughout the entire length of the device. The DBR laser includes a resonant cavity with a highly reflective DBR mirror at one end and a cleaved exit facet with low reflectivity at the other end. The laser is emitted from the exit facet opposite the DBR end. The DBR mirror reflects only a single longitudinal mode. Therefore, the laser operates in a single spatial and longitudinal mode. The resonant cavity includes a gain ridge portion. The DBR is continuously tunable by changing the injection current or temperature. Due to heating, an increase in current in the gain region causes the laser output to redshift. However, the reflectivity curve of the exit facet does not change. As a result, the exit facet will experience reflectivity loss at longer wavelengths and will eventually cause a discontinuous blue shift in wavelength to find a higher gain mode. Summary of the invention

[0004] One aspect of the present disclosure provides a method for field calibration of a laser transmitter. The method includes determining, by data processing hardware, that a connection between an optical line terminal (OLT) and an optical network unit (ONU) fails to meet a connection quality criterion. The ONU includes a distributed Bragg reflector (DBR) laser. The method further includes executing, by the data processing hardware, a self-calibration routine to determine an operating wavelength range of the DBR laser that maintains a connection between the OLT and the ONU and meets the connection quality criterion. The self-calibration routine iteratively includes the following: tuning an injection current of the DBR laser to adjust a communication wavelength of the ONU; determining whether the communication wavelength establishes or maintains a connection between the OLT and the ONU; when the communication wavelength establishes or maintains a connection between the OLT and the ONU, determining whether the connection meets the connection quality criterion; and when the connection meets the connection quality criterion, updating the operating wavelength range of the DBR laser to include the communication wavelength.

[0005] Another aspect of the present disclosure provides a system for field calibration of a laser transmitter. The system includes data processing hardware and memory hardware in communication with the data processing hardware. The memory hardware stores instructions that, when executed on the data processing hardware, cause the data processing hardware to perform operations. The operation includes determining that a connection between an optical line terminal (OLT) and an optical network unit (ONU) fails to meet a connection quality criterion. The ONU includes a distributed Bragg reflector (DBR) laser. The operation further includes executing a self-calibration routine to determine an operating wavelength range of the DBR laser that maintains a connection between the OLT and the ONU and meets the connection quality criterion. The self-calibration routine iteratively includes the following: tuning an injection current of the DBR laser to adjust a communication wavelength of the ONU; determining whether the communication wavelength establishes or maintains a connection between the OLT and the ONU; when the communication wavelength establishes or maintains a connection between the OLT and the ONU, determining whether the connection meets the connection quality criterion; and when the connection meets the connection quality criterion, updating the operating wavelength range of the DBR laser to include the communication wavelength.

[0006] Implementations of the present disclosure may include one or more of the following optional features. In some implementations, the connection quality criteria include satisfying at least one of a packet loss threshold, a frame loss (LOF) indicator, a start-up failure (SUF) indicator, or a connection loss indicator. In some examples, determining that the connection between the OLT and the ONU fails to satisfy the connection quality criteria includes receiving a physical layer operation, administration, and maintenance (PLOAM) message from the OLT indicating that the connection quality criteria cannot be satisfied. In some configurations, determining that the connection between the OLT and the ONU fails to satisfy the connection quality criteria includes receiving a frame loss (LOF) indicator, a signal loss (LOS) indicator, or a start-up failure (SUF) indicator from the firmware of the ONU. In some examples, determining that the connection between the OLT and the ONU fails to satisfy the connection quality criteria includes receiving a deactivation (DACT) indicator from the firmware of the ONU. In these examples, determining that the connection satisfies the connection quality criteria includes determining that the data processing hardware of the ONU has cleared the DACT indicator. Optionally, determining that the connection between the OLT and the ONU fails to meet the connection quality criterion includes receiving a loss of frame (LOF) indicator or a loss of signal (LOS) indicator from firmware of the OLT.

[0007] In some configurations, the self-calibration routine further includes determining a maximum wavelength of the operating wavelength range and a minimum wavelength of the operating wavelength range and setting the injection current of the DBR laser to an operating injection current within the operating wavelength range. In these configurations, the operating injection current includes an average or median value of the operating wavelength range.

[0008] Another aspect of the present disclosure provides a method for field calibration of a laser transmitter. The method includes receiving a downstream connection from an optical line terminal (OLT) at data processing hardware of an optical network unit (ONU), wherein the ONU includes a distributed Bragg reflector (DBR) laser. The method further includes attempting to establish an upstream connection between the ONU and the OLT by the data processing hardware. When the ONU establishes an upstream connection to the OLT, the method also includes receiving a message at the data processing hardware of the ONU to initiate calibration of the ONU, wherein the message is generated to indicate that the DBR laser is operating outside of an operating state. The method further includes tuning the DBR laser to an operating state by adjusting an injection current of the DBR laser through the data processing hardware of the ONU.

[0009] Another aspect of the present disclosure provides a system for field calibration of a laser transmitter. The system includes an optical network unit (ONU) including a distributed Bragg reflector (DBR) laser, data processing hardware, and memory hardware in communication with the data processing hardware. The memory hardware stores instructions that, when executed on the data processing hardware, cause the data processing hardware to perform operations. The operations include receiving a downstream connection from an optical line terminal (OLT) to the ONU. The operations further include attempting to establish an upstream connection between the ONU and the OLT. When the ONU establishes an upstream connection to the OLT, the operations also include receiving a message to initiate calibration of the ONU, wherein a message is generated to indicate that the DBR laser is operating outside of an operating state. The operations further include tuning the DBR laser to an operating state by adjusting an injection current of the DBR laser.

[0010] These aspects may include one or more of the following optional features. In some examples, tuning the DBR laser to an operational state includes: adjusting an injection current of the DBR laser to a first injection current; determining that the first injection current of the DBR laser establishes an upstream connection between the ONU and the OLT; identifying the first injection current as a first boundary of an operational window of the operational state of the DBR laser; adjusting the injection current of the DBR laser to a second injection current; determining that the second injection current of the DBR laser fails to maintain or establish an upstream connection between the ONU and the OLT; identifying the second injection current as a second boundary of the operational window of the operational state of the DBR laser; and supplying an operational injection current to the DBR laser, which may be between the first injection current and the second injection current. The operational injection current may be an average or median of the first injection current and the second injection current. In these examples, adjusting the injection current of the DBR laser to the first injection current may include incrementally changing the injection current. Determining that the second injection current for the DBR laser fails to maintain or establish an upstream connection between the ONU and the OLT may include receiving a start-up failure (SUF) indicator or a deactivation (DACT) indicator at the ONU. Receiving the DACT indicator at the ONU may indicate a failure to meet a bit error threshold. In these examples, when the ONU fails to establish an upstream connection to the OLT, the method may further include initiating calibration of the ONU. In addition, when the ONU establishes an upstream connection to the OLT, the method may further include communicating data from the ONU at a bit error rate that meets a bit error threshold, wherein the bit error threshold indicates an acceptable error level for data transmission through the ONU.

[0011] The details of one or more implementations of the disclosure are set forth in the drawings and description below.Other aspects, features, and advantages will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic diagram of an example communication system.

[0013] Figure 2A is a schematic diagram of an example communication system including an ONU having an environment for calibrating a DBR laser.

[0014] Figure 2B is a schematic diagram of an example multi-segment laser including a distributed Bragg reflector (DBR).

[0015] Figure 3A and 3B is a schematic diagram of an exemplary embodiment of ONU data processing hardware that implements a calibrator.

[0016] Figure 4 is a flow chart of an example operational arrangement for an in-situ calibration method for a DBR laser.

[0017] Figure 5 is a flow chart of an example operational arrangement for an in-situ calibration method for a DBR laser.

[0018] Figure 6 is a schematic diagram of an example computing device that can be used to implement the systems and methods described in this document.

[0019] Like reference numbers in the various drawings indicate like elements. DETAILED DESCRIPTION

[0020] More and more Internet Service Providers (ISPs) use Passive Optical Networks (PONs) to provide high-speed connections to private homes and small businesses. ISPs find PONs attractive due to high reliability and / or low cost. By using passive components to separate optical signals, PONs avoid the complexity of maintaining electrical equipment in outdoor environments. In a typical PON, one or more optical line terminals (OLTs) are installed at the ISP's central office (CO), and optical network units (ONUs) are installed at each user site away from the ISP's CO. The ONU typically includes a laser that generates an optical signal that is transmitted to the OLT. The ONU laser can be a distributed Bragg reflector (DBR) laser.

[0021] An ONU using a DBR laser may fail and require field replacement. Repairing or replacing a failed ONU may require dispatching a service technician to a remote user site. Until the service technician can access the user site, the user may not have network connectivity. One source of ONU failure is a reduction in optical signal power at the transmission wavelength of the DBR laser. An ONU that has failed in the field can be restored to operation by recalibrating the DBR laser.

[0022] The present disclosure describes, among other things, a method for in-situ calibration of a DBR laser. The method can be performed on a commercially available ONU without significantly increasing the cost or complexity of the ONU. By enabling the ONU to perform in-situ DBR laser calibration, a failed ONU can be restored to operation without imposing the cost or extended communication loss of a field replacement.

[0023] One aspect of the present disclosure provides a method for performing in-situ calibration of a distributed Bragg reflector (DBR) laser of an optical network unit (ONU) deployed in a passive optical network (PON) and optically coupled to an optical line terminal (OLT). In some examples, the OLT is located at a premises of a central office (CO) and optically coupled to a plurality of field-installed ONUs. In some examples, the ONUs are deployed at a site remote from the CO. The in-situ calibration method determines that a connection between the OLT and the ONU fails to meet a connection quality criterion and performs a self-calibration routine. The connection quality criterion is typically configured by a network entity to indicate when a connection may be compromised or degraded, thereby negatively affecting the ability of a user to communicate data with the PON. The self-calibration routine determines an operating wavelength range of the DBR laser that maintains a connection between the OLT and the ONU and meets the connection quality criterion. The self-calibration tuning routine may include tuning an injection current of the DBR laser to adjust a communication wavelength of the ONU and determining whether the communication wavelength establishes or maintains a connection between the OLT and the ONU. The tuning routine may further include determining whether the connection satisfies a connection quality criterion and updating an operating wavelength range of the DBR laser when the connection satisfies the connection quality criterion.

[0024] This aspect of the disclosure may include one or more of the following optional features. In some examples, the communication quality criterion includes satisfying at least one of a packet loss threshold, a loss of frame (LOF) indicator, a start-up failure (SUF) indicator, or a connection loss indicator. In other examples, the communication quality criterion is a bit error rate (BER) of less than one (1) part per thousand (1000). Another aspect of the disclosure provides that determining whether a communication wavelength establishes or maintains a connection between an OLT and an ONU includes receiving a physical layer operations, administration, and maintenance (PLOAM) message from the OLT indicating that the connection quality criterion has not been satisfied.

[0025] refer to Figure 1, an optical communication system 100 delivers communication signals 102 (e.g., optical signals) over communication links 110, 112, 112a-n (e.g., optical fiber or line-of-sight free-space optical communications) between an optical line terminal (OLT) 120 housed in a central office (CO) 130 and optical network units (ONUs) 140, 140a-n (e.g., optical transceivers) associated with users 150, 150a-n (also referred to as customers or subscribers). The ONUs 140, 140a-n are typically located at premises 152, 152a-n of the users 150, 150a-n.

[0026] Customer Premises Equipment (CPE) is any terminal and associated equipment located at the premises 152 of a user 150 and connected to the operator's telecommunications channel C at a demarcation point ("demarcation"). The demarcation is a point established in a house, building, or group of buildings to separate customer equipment from service provider equipment (SPE). Some examples of CPE include phones, routers, switches, residential gateways (RGs), set-top boxes, fixed-mobile convergence products, home networking adapters, or Internet access gateways, which enable users 150 to access the services of a communications service provider and distribute them around the premises 152 of the user 150 via a local area network (LAN). In the example shown, ONU 140 is a CPE.

[0027] In some implementations, the optical communication system 100 implements an optical access network 105 (such as a passive optical network (PON) 105), for example, for access and mobile fronthaul / backhaul networks. Some examples of the optical access network 105 include a 10 Gigabit capable PON (XG-PON), a 10 Gigabit capable symmetric PON (XGS-PON), a next generation PON (NG-PON), and other PONs that comply with International Telecommunication Union (ITU) standards. In some examples, the optical communication system 100 implements a point-to-point (pt-2-pt) PON with direct connections such as optical Ethernet, where the home optical links 110, 112 (e.g., optical fiber) extend all the way back to the OLT 120 at the CO 130 and each customer 150, 150a-n is terminated by a separate OLT 120a-n. In other examples, the optical communication system 100 implements a point-to-multipoint (pt-2-multi-pt) PON, where a shared OLT 120 serves multiple customers 150, 150a-n.

[0028] For example, the CO 130 includes at least one OLT 120 that connects the optical access network 105 to an Internet Protocol (IP), asynchronous transfer mode (ATM), or synchronous optical networking (SONET) backbone. Thus, each OLT 120 is an endpoint of the PON 105 and converts between electrical signals used by service provider equipment and optical signals 102 used by the PON 105. Depending on the implementation of the optical access network 105, each OLT 120, 120a-n includes at least one transceiver 122, 122a-n. The OLT 120 transmits the optical signal 102 via the corresponding transceiver 122 over the feeder optical fiber 110 to a remote node (RN) 170, which includes a band multiplexer 160 configured to demultiplex the optical signal 102 and distribute the demultiplexed optical signal 104 along the corresponding distribution optical fiber 112, 112a-n to a plurality of users 150, 150a-n. The band multiplexer 160 for multiplexing / demultiplexing may be an array wavelength grating (AWG) 180, which is a passive optical device. In some examples, each CO 130 includes a plurality of OLTs 120, 120a-n, and each OLT 120 is configured to serve a group of users 150. In addition, each OLT 120 may be configured to provide signals in different services. For example, one OLT 120 provides services in an XG-PON, while another OLT 120 provides services in an NG-PON.

[0029] like Figure 1 As shown in FIG. 1 , CO 130 multiplexes signals received from several sources, such as video media distribution source 132, Internet data source 134, and voice data source 136, and multiplexes the received signals into one multiplexed signal 102 before sending the multiplexed optical signal 102 to RN 170 through feeder optical fiber 110. The multiplexing may be performed by OLT 120 or a broadband network gateway (BNG) located at CO 130. Typically, services are time-division multiplexed at the packet layer.

[0030] Time division multiplexing (TDM) is a method of transmitting and receiving independent signals over a common signal path by using different non-overlapping time slots. Wavelength division multiplexing (WDM) uses multiple wavelengths λ to achieve point-to-multipoint communication in PON 105. OLT 120 provides multiple wavelengths to band multiplexer 160 at RN 170 via one optical fiber 110, which multiplexes / demultiplexes the signals between OLT 120 and multiple ONUs 140, 140a-n. Multiplexing combines several input signals and outputs the combined signal. Time-division wavelength division multiplexing (TWDM) uses the time dimension and the wavelength dimension to multiplex the signals.

[0031] For WDM and dense WDM (DWDM), the OLT 120 includes a plurality of optical transceivers 122, 122a-n. Each optical transceiver 122 transmits at a fixed wavelength λ D (called downstream wavelength) and transmits signals at a fixed wavelength λ U (referred to as the upstream wavelength) receives the optical signal 102. The downstream wavelength λ D and upstream wavelength λ U can be the same or different. In addition, channel C can define a pair of downstream wavelengths λ D and upstream wavelength λ U , and each optical transceiver 122, 122a-n of the corresponding OLT 120 may be assigned a unique channel C a-n .

[0032] The OLT 120 provides channels C, C a-n Multiplexing / demultiplexing is performed for transmitting the optical signal 102 through the feeder optical fiber 110. However, the band multiplexer 160 at the RN 170 multiplexes / demultiplexes the optical signals 102, 104, 104a-n between the OLT 120 and the plurality of ONUs 140, 140a-n. For example, for downstream communication, the band multiplexer 160 demultiplexes the optical signal 102 from the OLT 120 into the ONU optical signals 104, 104a-n, (i.e., for each corresponding ONU 140, 140a-n, the downstream optical signal 104d). For upstream communication, the band multiplexer 160 multiplexes the ONU optical signals 104, 104a-n from each corresponding ONU 140, 140a-n (i.e., the upstream optical signal 104u, multiplexed into the optical signal 102 for delivery to the OLT 120). In order for the transmission to be successful, the optical transceivers 122, 122a-n of the OLT 120 are matched individually to the ONUs 140, 140a-n. In other words, the downstream wavelength λ of the corresponding downstream optical signal 104d and upstream optical signal 104u to and from a given ONU 140 is D and upstream wavelength λ U (ie, channel C) and the corresponding downstream wavelength λ of the optical transceiver 122 D and upstream wavelength λ U (ie, channel C) matches.

[0033] refer to Figure 2A, each OLT 120 may include data processing hardware 124 and memory hardware 126 in communication with the data processing hardware 124. Examples of the data processing hardware 124 include control hardware, circuits, field programmable gate arrays (FPGAs), etc. The memory hardware 126 may store instructions (e.g., via firmware) that, when executed on the data processing hardware 124, cause the data processing hardware 124 to perform operations to determine that a connection 320 between an optical line terminal (OLT) 120 and an optical network unit (ONU) 140 fails to meet one or more connection quality criteria 330. In some implementations, the quality criterion is a bit error rate (BER) of an upstream optical signal 104u from the ONU 140 that is less than one (1) in one thousand (1000). Other bit error rate criteria may also be used. In some examples, the data processing hardware 124 of the OLT 120 determines that there is a signal loss from the ONU 140. In some examples, the data processing hardware 124 of the OLT 120 detects a loss of frame (LOF) in the upstream optical signal 140u from the ONU 140 (e.g., when the OLT 120 receives at least four invalid delimiters from the ONU 140). In some examples, the data processing hardware 124 of the OLT 120 transmits a message 312 to the ONU 140 indicating that the connection 320 fails to meet one or more connection quality criteria 330. The message 312 may be a physical layer operations, administration, and maintenance (PLOAM) message. The PLOAM message format is defined in the International Telegraph Union-Telecommunication Standardization Sector (ITU-T) standard G.984.3 Gigabit Passive Optical Network (G-PON): Transmission Convergence Layer Specification. In some implementations, the message 312 is a PLOAM deactivation (DACT) message. In some implementations, a custom PLOAM message is transmitted. The message may also be any message indicating that the connection 320 fails to meet one or more connection quality criteria 330.

[0034] The ONUs 140, 140a-n are typically located at a premises 152, 152a-n of a user 150, 150a-n. In some implementations, each ONU 140, 140a-n includes a corresponding optical transceiver 142, 142a-n (e.g., including a laser or a light emitting diode). In some examples, the optical transceiver 142 includes a distributed Bragg reflector (DBR) laser 200. Each ONU 140 may include data processing hardware 144 and memory hardware 146 that communicates with the data processing hardware 144. Examples of the data processing hardware 144 include control hardware, circuits, field programmable gate arrays (FPGAs), etc. In some examples, the data processing hardware 144 includes a digital-to-analog converter (DAC) 210. The DAC 210 may include a DAC configuration 370 ( Figure 3A). In other examples, the data processing hardware 144 can communicate with a digital-to-analog converter (DAC) 210 (e.g., via a communication bus). The DAC 210 can be configured by the data processing hardware 144 to supply an injection current 212 to the DBR laser 200. The injection current 212 ( Figure 2B ) to tune the wavelength of the DBR laser 200. The memory hardware 146 may store instructions (e.g., via firmware) that, when executed on the data processing hardware 144, cause the data processing hardware 144 to perform operations to adjust the injection current 212 applied to the DBR laser 200. The ONU 140 may include a photodetector that converts the downstream optical signal 104d from the OLT 120 into electrical form. The electrical signal may be further demultiplexed into subcomponents (e.g., data on a network, converting sound waves into electrical current using a microphone and back to their original physical form using a speaker, converting images into electrical current using a camera and back to physical form using a television or other video display).

[0035] Figure 2B An example DBR laser 200 is depicted. Some configurations include a multi-segment structure where each segment / structure shares a single substrate. As an example, the segments may include a gain segment, a phase segment, an electro-absorption (EA) segment, a distributed Bragg reflector (DBR) segment, and a thermoelectric cooling segment / module (TEC). In this example, each segment has a P-doped indium phosphide (InP) region on a shared N-doped InP substrate that forms a corresponding diode (D0, D1, D2, D3) with a common cathode. These diodes can be driven by a corresponding injection current (I GAIN ,I PHASE ,I DBR ) or voltage (V EA ) is driven. The DBR laser includes a resonant cavity 214 having a highly reflective DBR mirror at one end and a low reflectivity split exit facet at the other end. The resonant cavity 214 includes a gain ridge portion. The DBR segment is continuously tunable by changing the injection current 212 or temperature. In some configurations, the DAC 210 provides the injection current 212 to the DBR segment 214 of the laser 200. Adjusting the injection current 212 can change the refractive index of the DBR segment 214 of the laser 200, shifting the resonant wavelength of the DBR cavity 214.

[0036] As the resonant wavelength of the DBR cavity 214 shifts, the laser power in the main spectrum peak may become smaller, thereby affecting the power of the upstream optical signal 104u from the ONU 140. In addition, the power in other (side) resonant modes of the DBR section 214 may increase. The difference between the main spectrum peak and the maximum side mode power defines the side mode suppression ratio (SMSR). Therefore, as the resonant wavelength of the DBR section 214 shifts, the SMSR of the upstream optical signal 104u from the ONU 140 may decrease. When the SMSR is outside the acceptable range, the upstream optical signal 104u from the ONU 140 may not meet the connection quality criteria 330.

[0037] Tuning the injection current 212 to the DBR section 214 of the laser 200 may also advantageously shift the resonant wavelength, thereby causing an increase in the SMSR of the upstream optical signal 104u from the ONU 140. In an example, the DBR section 214 may experience an increase in the resonant frequency over time, thereby allowing the side mode to become more dominant. The SMSR of the upstream optical signal 104u from the ONU 140 decreases accordingly over time. The upstream optical signal 104u from the ONU 140 may not meet the connection quality criterion 330. Increasing the injection current 212 provided to the DBR section 214 of the laser 200 causes a red shift in the resonant wavelength of the DBR cavity 214 due to heating. In an example, the red shift partially or completely compensates for the increase in the resonant frequency over time. Therefore, the SMSR of the upstream optical signal 104u from the ONU 140 can increase. When the SMSR is within an acceptable range, the upstream optical signal 104u can meet the connection quality criterion 330.

[0038] Figure 3A and 3BThe communication between the OLT 120 and the ONU 140 is illustrated to detect and / or initiate calibration of the DBR laser 200. These processes allow the calibrator 300 to evaluate whether the connection between the OLT 120 and the ONU 140 can adequately convey data for the user 150. In some examples, the calibrator 300 detects a loss of the upstream optical signal 104u from the ONU 140. In some examples, the calibrator 300 determines that the upstream optical signal 104u from the ONU 140 fails to meet the connection quality criteria 330. When the SMSR is outside of an acceptable range, the calibrator 300 can determine that the upstream optical signal 104u fails to meet the connection quality criteria 330. In other words, the calibrator 300 allows the PON system 105 to sense when the resonant wavelength of the DBR segment 214 drifts outside of the operating wavelength range 350. The calibrator 300 performs operations (e.g., methods 400, 500) for in-situ calibration of the DBR laser 200. In some implementations, the data processing hardware 144 of the ONU 140 executes the calibrator 300. In other implementations, the calibrator 300 is executed in whole or in part by any suitable computing device 600 ( Figure 6 ) (e.g., executed by data processing hardware 124 of OLT 120 or other computing equipment 600 located in the central office of the ISP).

[0039] Figure 3A An example calibrator 300 is shown executing on the data processing hardware 144 of the ONU 140. In some examples, the data processing hardware 124 of the OLT 120 determines that the upstream optical signal 104u from the ONU 140 fails to meet the connection quality criteria 330. Here, the OLT 120 can determine that the upstream optical signal 104u fails to meet the connection quality criteria 330 when the upstream optical signal 104u includes a loss of frame (LOF). For example, when the OLT 120 receives at least four invalid delimiters in the upstream optical signal 104u from the ONU 140, the OLT 120 can identify the LOF in the upstream optical signal 104u. In an additional example, when the OLT 120 detects that the bit error rate (BER) of the upstream optical signal 104u is greater than 10 -yWhen y is a configurable number between 3 and 8, the upstream optical signal 104u fails to meet the connection quality criteria 330, as defined in ITU-T Standard G.984.3 Gigabit-Capable Passive Optical Network (G-PON): Transmission Convergence Layer Specification. When the upstream optical signal 104u from the ONU 140 fails to meet the connection quality criteria 330, the data processing hardware 124 of the OLT 120 can transmit a PLOAM deactivation message 312 to the ONU 140. In some examples, the OLT 120 transmits the PLOAM message 312 to the ONU 140 using a downstream connection 310 between the OLT 120 and the ONU 140. In these examples, the downstream connection 310 can be established by transmitting the downstream optical signal 104d from the OLT 120 to the ONU 140. The data processing hardware 144 of the ONU 140 may receive the PLOAM message 312 and issue a DACT indicator upon receiving the PLOAM deactivation message 312 as defined in ITU-T Standard G.984.3 Gigabit-Capable Passive Optical Network (G-PON): Transmission Convergence Layer Specification.

[0040] In an additional example, the data processing hardware 144 of the ONU 140 issues a start-up failure (SUF) indicator. The data processing hardware 144 of the ONU 140 may issue the SUF indicator when the ONU 140 fails to establish an upstream connection 320 with the OLT 120 after one or more attempts. In response to the DACT or SUF indicator issued by the ONU 140, the calibrator 300 may determine that the upstream connection 320 with the OLT 120 has failed.

[0041] When the calibrator 300 determines that the upstream connection 320 with the OLT 120 has failed, the calibrator 300 performs a self-calibration of the DBR laser 200 to determine an operating wavelength range 350 of the DBR segment 214 that establishes and maintains the upstream connection 320 with the OLT 120. In addition, the self-calibration may determine an operating wavelength range 350 having a communication wavelength that satisfies one or more connection quality criteria 330. In some examples, the communication wavelength that satisfies the one or more connection quality criteria 330 defines an operable state of the DBR laser 200. The connection quality criteria 330 may include or require a communication from the ONU 140 having a bit error rate (BER) that satisfies a bit error threshold. The bit error threshold may indicate an acceptable error level for data transmission through the ONU 140 that satisfies the connection quality criteria 330. The bit error threshold may be 10 -y , such as one in every kilobits transmitted (e.g., one in 1,000), where y is a configurable number between three and eight.

[0042] The self-calibration may determine an adjustable injection current range 340 of the injection current 212 that the DAC 210 applies to the DBR section 214 of the laser 200. The calibrator 300 may obtain an operational injection current range 360 ​​of the injection current 212 by iteratively adjusting the injection current 212 within the adjustable injection current range 340. When the calibrator 300 iteratively adjusts the injection current 212 of the DBR section 214 of the laser 200, the ONU 140 transmits the upstream optical signal 104u to the OLT 120. When the ONU 140 transmits the upstream optical signal 104u to the OLT 120, the calibrator 300 determines whether a connection 320 with the OLT 120 is established. In some examples, the data processing hardware 124 of the OLT 120 also monitors whether the upstream optical signal 104u from the ONU 140 satisfies the connection quality criteria 330. When the connection 320 with the OLT is established and the upstream optical signal 104u from the ONU 140 meets the connection quality criteria 330, the data processing hardware 124 of the OLT 120 can transmit a PLOAM message 312 to the data processing hardware 144 of the ONU 140. In some examples, when the data processing hardware 144 receives the PLOAM message 312, the data processing hardware 144 of the ONU 140 clears or deasserts the previously issued DACT indicator. In some implementations, the calibrator 300 determines that the upstream connection 320 with the OLT 120 is established when the data processing hardware 144 of the ONU 140 clears the SUF and DACT indicators. When the calibrator 300 determines that the upstream connection 320 with the OLT 120 has been established, the calibrator 300 can record the associated injection current 212. In other implementations, the calibrator 300 records the wavelength of the DBR laser 200 associated with the established upstream connection 320 with the OLT 120. In some examples, the calibrator 300 records the DAC configuration 370 associated with the established upstream connection 320 as the operating injection current 212 OPER .

[0043] In some configurations, the calibrator 300 determines the minimum injection current 212 in the operating injection current range 360. MIN and the maximum injection current 212 MAX Calibrator 300 may configure DAC 210 to operate injection current 212 OPER applied to the DBR segment 214 of the laser 200, which operates the injection current 212 OPER is within the operating injection current range 360. In some examples, the calibrator 300 determines the average injection current 212 in the operating injection current range 360 MEAN Or median injection current 212 MED Calibrator 300 may configure DAC 210 to convert average injection current 212MEAN Or median injection current 212 MED The calibrator 300 may record the injection current 212 applied to the DBR segment 214 of the laser 200 in the non-transitory memory of the data processing hardware 144. In an additional example, the calibrator 300 records the injection current 212 applied to the DBR segment 214 of the laser 200 in the non-transitory memory of the data processing hardware 144. OPER The DAC configuration 370 is recorded in the memory hardware 146 of the ONU 140 ( Figure 2A ).

[0044] refer to Figure 3B , the data processing hardware 124 of the OLT 120 can monitor one or more signal quality criteria of the upstream optical signal 104u from the ONU 140. The data processing hardware 124 can determine that the connection 320 with the ONU 140 is poor. In some examples, determining that the connection 320 with the ONU 140 is poor includes detecting a loss of the upstream optical signal 104u from the ONU 140. In some examples, the data processing hardware 124 determines that the upstream optical signal 104u fails to meet one or more connection quality criteria 330. When the SMSR is outside of an acceptable range, the upstream optical signal 104u from the ONU 140 may fail to meet the connection quality criteria 330. When the connection 320 with the ONU 140 is poor, the data processing hardware 124 of the OLT 120 can transmit a PLOAM message 312 to the data processing hardware 144 of the ONU 140. In some examples, the calibrator 300 ignores the PLOAM message 312 when a self-calibration has been recently performed (e.g., within the previous 20 minutes). In some examples, the calibrator 300 performs a self-calibration of the DBR laser 200 to determine an operating wavelength range 350 of the DBR segment 214 that maintains a connection 320 with the OLT 120. In addition, the self-calibration can determine an operating wavelength range 350 having communication wavelengths that satisfy one or more connection quality criteria 330. The connection quality criteria 330 can include or define a bit error rate (BER) of the upstream optical signal 104u from the ONU 140 that satisfies the connection quality criteria 330. The calibrator 300 can determine a minimum wavelength λ within the operating wavelength range 350. MIN and maximum wavelength λ MAX .

[0045] Similar to Figure 3A, the self-calibration may include determining an adjustable injection current range 340 of the injection current 212 that the DAC 210 applies to the DBR section 214 of the laser 200. The calibrator 300 may obtain an operational injection current range 360 ​​of the injection current 212 by iteratively adjusting the injection current 212 within the adjustable injection current range 340. When the calibrator 300 determines to establish an upstream connection 320 with the OLT 120, the calibrator 300 may record the associated injection current 212. In further implementations, the calibrator 300 records the wavelength of the DBR laser 200 associated with the established upstream connection 320 with the OLT 120. In further implementations, the calibrator 300 records the DAC configuration 370 of the DAC 210 associated with the established upstream connection 320 with the OLT 120.

[0046] In some examples, the calibrator 300 determines the minimum injection current 212 in the operating injection current range 360. MIN and the maximum injection current 212 MAX . Minimum injection current 212 MIN Defines the first boundary of the operating window of the DBR laser 200. Maximum injection current 212 MAX The calibrator 300 may determine the average injection current 212 in the operating injection current range 360. MEAN Or median injection current 212 MED In some examples, calibrator 300 configures DAC 210 to convert average injection current 212 MEAN Or median injection current 212 MED The DBR segment 214 applied to the laser 200. The calibrator 300 may record the injection current 212 applied to the DBR laser 200 in the memory hardware 126,146.

[0047] Figure 4 An example operational arrangement of a method 400 for performing in-situ calibration of a DBR laser 200 is provided. Here, an ONU 140 is deployed in a PON 105 and optically coupled to an OLT 120. At operation 402, the method 400 determines that a connection 320 between the ONU 140 and the OLT 120 fails to satisfy a connection quality criterion 330. Satisfying the connection quality criterion 330 may include satisfying at least one of a bit error rate (BER) threshold, a loss of frame (LOF) indicator, a start-up failure (SUF) indicator, or a connection loss indicator. At operation 404, the method 400 performs a self-calibration routine to determine an operating wavelength range 350 of the DBR laser 200 that maintains the connection 320 between the OLT 120 and the ONU 140 and satisfies the connection quality criterion 330. Executing the self-calibration routine includes iteratively performing operations 406-412.

[0048] At operation 406, the method 400 tunes the injection current 212 of the DBR section 214 of the laser 200 to adjust the communication wavelength of the ONU 140. Here, the method 400 configures the DAC 210 to supply the injection current 212 to the DBR section 214 of the laser 200, whereby the DAC 210 includes the DAC configuration 370. At operation 408, the method 400 determines whether the communication wavelength establishes or maintains the connection 320 between the OLT 120 and the ONU 140. When the communication wavelength fails to establish or maintain the connection 320 (e.g., operation 408 is "no"), the method 400 returns to operation 406. On the other hand, when the communication wavelength establishes or maintains the connection 320 (e.g., operation 408 is "yes"), the method 400 enters operation 410 to determine whether the connection 320 satisfies the connection quality criteria 330. When the connection 320 fails to satisfy the connection quality criteria 330 (e.g., operation 410 is “no”), the method 400 returns to operation 406. On the other hand, when the connection 320 satisfies the connection quality criteria 330 (e.g., operation 410 is “yes”), the method 400 proceeds to operation 412 and updates the operating wavelength range 350 of the DBR section 214 of the laser 200 to include the communication wavelength. In some examples, the method 400 records the DAC configuration 370 associated with the operating wavelength range 350.

[0049] Figure 5An example operational arrangement of a method 500 for performing an in-situ calibration of a DBR laser 200 of an ONU 140 is provided, wherein the ONU 140 is deployed in a PON 105 and optically coupled to an OLT 120. At operation 502, the method 500 receives a downstream connection 310 from the OLT 120 at the ONU 140. The downstream connection 310 may be established by transmitting a downstream optical signal 104d from the OLT 120 and receiving the downstream signal 104d at the ONU 140. At operation 504, the method 500 attempts to establish an upstream connection 320 with the OLT 120. The upstream connection 320 may be established by transmitting an upstream optical signal 104u from the ONU 140 and receiving the upstream signal 104u at the OLT 120. The upstream connection 320 may fail to satisfy a connection quality criterion 330. Failure to satisfy the connection quality criterion 330 may indicate that the DBR laser 200 is operating outside of an operating state defined by the connection quality criterion 330. When the SMSR of the upstream optical signal 104u from the ONU 140 is outside the acceptable range, the DBR laser 200 may be operated outside the operating state. At operation 506, the method 500 receives a message 312 from the OLT 120 to initiate calibration of the ONU 140. Here, the message 312 may be generated by the OLT 120 to indicate that the DBR laser 200 is operating outside the operating state. Some examples of the message 312 include a PLOAM message, a message complying with Technical Report 069 (TR-069) or other CPE remote management specifications, and a command issued from the central office of the ISP via TELNET or other remote execution protocol.

[0050] At operation 508, the method 500 configures the DAC 210 to incrementally adjust the injection current 212 supplied to the DBR section 214 of the laser 200. Here, the DAC 210 includes the DAC configuration 370. In some implementations, the method 500 monotonically increases the injection current 212 from a low current to a high current. The method may also monotonically decrease the current from a high current to a low current. Other incremental adjustment techniques may also be used. At operation 510, the method 500 determines whether the upstream connection 320 satisfies the connection quality criteria 330. Satisfying the connection quality criteria 330 may indicate that the DBR laser 200 is operating within an operating state. When the SMSR of the upstream optical signal 104u from the ONU 140 is within an acceptable range, the DBR laser 200 may operate within an operating state. When the upstream connection 320 fails to meet the connection quality criteria 330 (e.g., operation 510 is "no"), the method 500 returns to operation 508. On the other hand, when the upstream connection 320 satisfies the connection quality criteria 330, the method 500 proceeds to operation 512 and determines whether the injection current 212 establishes a first boundary of the operating window of the DBR laser 200. When the injection current 212 fails to establish the first boundary (e.g., operation 512 is "no"), the method 500 returns to operation 508. On the other hand, when the injection current 212 establishes the first boundary of the operating window of the DBR laser 200 (e.g., operation 512 is "yes"), the method 500 proceeds to operation 514 and identifies the first injection current 212 as the first boundary of the operating window of the DBR laser 200. In some examples, the first injection current is a minimum injection current 212 associated with the operating window of the DBR laser 200. MIN .

[0051] At operation 516, the method 500 determines whether the injection current 212 establishes a second boundary of the operating window of the DBR laser 200. When the first injection current 212 fails to satisfy the connection quality criteria at operation 512, the method 500 may perform operation 516 after adjusting the injection current at operation 508. When the injection current 212 fails to establish the second boundary (e.g., operation 516 is "no"), the method 500 returns to operation 508. On the other hand, when the injection current 212 establishes the second boundary of the operating window of the DBR laser 200 (e.g., operation 516 is "yes"), the method 500 proceeds to operation 518 and identifies the second injection current 212 as the second boundary of the operating window of the DBR laser 200. In some examples, the second injection current is a maximum injection current 212 associated with the operating window of the DBR laser 200. MAX .

[0052] At operation 510, the method 500 supplies an operating injection current to the DBR laser 200, the operating injection current being at a first injection current 212 MINand the second injection current 212 MAX In some examples, the operating injection current is the first injection current 212 MIN and the second injection current 212 MAX The median or average value.

[0053] A software application (i.e., software resource) may refer to computer software that enables a computing device to perform tasks. In some examples, a software application may be referred to as an "application," "app," or "program." Example applications include, but are not limited to, system diagnostic applications, system management applications, system maintenance applications, word processing applications, spreadsheet applications, messaging applications, media streaming applications, social networking applications, and gaming applications.

[0054] Non-transitory memory can be a physical device used to store programs (e.g., sequences of instructions) or data (e.g., program state information) on a temporary or permanent basis for use by a computing device. Non-transitory memory can be volatile and / or non-volatile addressable semiconductor memory. Examples of non-volatile memory include, but are not limited to, flash memory and read-only memory (ROM) / programmable read-only memory (PROM) / erasable programmable read-only memory (EPROM) / electronically erasable programmable read-only memory (EEPROM) (e.g., commonly used for firmware, such as bootloaders). Examples of volatile memory include, but are not limited to, random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), phase change memory (PCM), and disk or tape.

[0055] Figure 6 6 is a schematic diagram of an example computing device 600 that can be used to implement the systems and methods (e.g., calibrator 300) and methods (e.g., methods 400, 500) described in this document. Computing device 600 is intended to represent various forms of digital computers, such as laptops, desktops, workstations, personal digital assistants, servers, blade servers, mainframes, and other appropriate computers. The components shown here, their connections and relationships, and their functions are intended to be exemplary only and are not intended to limit the implementation of the inventions described and / or claimed in this document.

[0056] The computing device 600 includes a processor 610 (e.g., data processing hardware 124, 144), a memory 620 (e.g., memory hardware 126, 146), a storage device 630, a high-speed interface / controller 640 connected to the memory 620 and a high-speed expansion port 650, and a low-speed interface / controller 660 connected to a low-speed bus 670 and the storage device 630. Each of the components 610, 620, 630, 640, 650, and 660 are interconnected using various buses and can be mounted on a common motherboard or otherwise as appropriate. The processor 610 is capable of processing instructions for execution within the computing device 600, including instructions stored in the memory 620 or stored on the storage device 630 to display graphical information for a graphical user interface (GUI) on an external input / output device such as a display 680 coupled to the high-speed interface 640. In other implementations, multiple processors and / or multiple buses and multiple memories and multiple types of memories can be used as appropriate. Additionally, multiple computing devices 600 may be connected, with each device providing portions of the necessary operations (eg, as a server bank, a group of blade servers, or a multi-processor system).

[0057] The memory 620 stores information within the computing device 600 non-temporarily. The memory 620 may be a computer-readable medium, a volatile memory unit, or a non-volatile memory unit. The non-temporary memory 620 may be a physical device for storing programs (e.g., sequences of instructions) or data (e.g., program state information) on a temporary or permanent basis for use by the computing device 600. Examples of non-volatile memory include, but are not limited to, flash memory and read-only memory (ROM) / programmable read-only memory (PROM) / erasable programmable read-only memory (EPROM) / electronically erasable programmable read-only memory (EEPROM) (e.g., typically used for firmware, such as bootloaders). Examples of volatile memory include, but are not limited to, random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), phase change memory (PCM), and disk or tape.

[0058] The storage device 630 can provide mass storage for the computing device 600. In some implementations, the storage device 630 is a computer readable medium. In various implementations, the storage device 630 can be a floppy disk device, a hard disk device, an optical disk device or a tape device, a flash memory or other similar solid-state storage device or array of devices, including devices in a storage area network or other configurations. In additional implementations, a computer program product is tangibly embodied in an information carrier. The computer program product includes instructions that, when executed, perform one or more methods, such as the above-described methods. The information carrier is a computer or machine readable medium, such as a memory 620, a storage device 630, or a memory on a processor 610.

[0059] The high-speed controller 640 manages bandwidth-intensive operations of the computing device 600, while the low-speed controller 660 manages less bandwidth-intensive operations. This allocation of responsibilities is exemplary only. In some implementations, the high-speed controller 640 is coupled to the memory 620, the display 680 (e.g., through a graphics processor or accelerator), and is coupled to the high-speed expansion port 650, which can accept various expansion cards (not shown). In some implementations, the low-speed controller 660 is coupled to the storage device 630 and the low-speed expansion port 690. The low-speed expansion port 690, which can include various communication ports (e.g., USB, Bluetooth, Ethernet, wireless Ethernet), can be coupled to one or more input / output devices (e.g., through a network adapter), such as a keyboard, a pointing device, a scanner, or a networking device such as a switch or a router.

[0060] As shown in the figure, the computing device 600 can be implemented in many different forms. For example, it can be implemented as a standard server 600a or multiple times in a group of such servers 600a, as a laptop computer 600b or as part of a rack server system 600c. In some examples, the computing device 600 can be partially or completely implemented as a part of the ONU 140 in the optical communication system 100.

[0061] Various implementations of the systems and techniques described herein can be realized in digital electronic and / or optical circuits, integrated circuits, specially designed ASICs (application specific integrated circuits), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include implementations in one or more computer programs that are executable and / or interpretable on a programmable system that includes at least one programmable processor, which can be special-purpose or general-purpose, coupled to receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, at least one input device, and at least one output device.

[0062] These computer programs (also referred to as programs, software, software applications, or code) include machine instructions for a programmable processor and can be implemented in high-level procedural and / or object-oriented programming languages ​​and / or in assembly / machine languages. As used herein, the terms "machine-readable medium" and "computer-readable medium" refer to any computer program product, non-transitory computer-readable medium, apparatus, and / or device (e.g., disk, optical disk, memory, programmable logic device (PLD)) for providing machine instructions and / or data to a programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal. The term "machine-readable signal" refers to any signal for providing machine instructions and / or data to a programmable processor.

[0063] The process and logic flow described in this specification can be executed by one or more programmable processors to perform one or more computer programs to perform functions by operating on input data and generating outputs. The process and logic flow can also be performed by a dedicated logic circuit such as an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). For example, a processor suitable for executing a computer program includes both a general-purpose microprocessor and a special-purpose microprocessor and any one or more processors of any kind of digital computer. Typically, the processor will receive instructions and data from a read-only memory or a random access memory or both. The necessary elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Typically, a computer will also include one or more mass storage devices (such as disks, magneto-optical disks, or optical disks) for storing data, or be operationally coupled to receive data from the one or more mass storage devices or transfer data to the one or more mass storage devices, or both. However, a computer does not have to have such devices. Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media, and memory devices, including, by way of example, semiconductor memory devices (e.g., EPROM, EEPROM, and flash memory devices); magnetic disks (e.g., internal hard disks or removable disks, magneto-optical disks, and CD ROM and DVD-ROM disks). The processor and memory can be supplemented by, or incorporated in, special purpose logic circuits.

[0064] In order to provide interaction with a user, one or more aspects of the present disclosure can be implemented on a computer having a display device; for example, a CRT (cathode ray tube), LCD (liquid crystal display) monitor or touch screen for displaying information to the user, and optionally a keyboard and pointing device (such as a mouse or trackball) that the user can use to provide input to the computer. Other types of devices can also be used to provide interaction with the user. For example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback) and input from the user can be received in any form, including acoustic, voice, or tactile input. In addition, the computer can interact with the user by sending documents to or receiving documents from a device used by the user; for example, by sending a web page to a web browser on a user's client device in response to a request received from the web browser.

[0065] Many implementations have been described. However, it should be understood that various modifications can be made without departing from the spirit and scope of the present disclosure. Therefore, other implementations are within the scope of the following claims.

Claims

1. A method (400) for calibrating a laser transmitter, comprising: Determining, by data processing hardware (144), that a connection between an optical line terminal (OLT) (120) and an optical network unit (ONU) (140) fails to meet a connection quality criterion (330), the ONU (140) including a distributed Bragg reflector (DBR) laser (200); as well as A self-calibration routine is performed by the data processing hardware (144) to determine an operating wavelength range (350) of the DBR laser (200) that maintains the connection between the OLT (120) and the ONU (140) and satisfies the connection quality criteria (330), the self-calibration routine comprising iteratively performing: Tuning the injection current (212) of the DBR laser (200) to adjust the communication wavelength of the ONU (140); determining whether the communication wavelength establishes or maintains a connection between the OLT (120) and the ONU (140); When the communication wavelength establishes or maintains a connection between the OLT (120) and the ONU (140), determining whether the connection satisfies the connection quality criterion (330); and When the connection satisfies the connection quality criterion (330), the operating wavelength range (350) of the DBR laser (200) is updated to include the communication wavelength.

2. The method (400) of claim 1, wherein the connection quality criteria (330) comprises satisfying at least one of: a packet loss threshold, a frame loss LOF indicator, a start failure SUF indicator, or a connection loss indicator.

3. The method (400) of claim 1, wherein determining that the connection between the OLT (120) and the ONU (140) fails to meet the connection quality criterion (330) comprises receiving a physical layer operations, administration, and maintenance (PLOAM) message (312) from the OLT (120) indicating that the connection quality criterion (330) fails to be met.

4. The method (400) of claim 1, determining that the connection between the OLT (120) and the ONU (140) fails to meet the connection quality criteria (330) comprises receiving a loss of frame (LOF) indicator, a loss of signal (LOS) indicator, or a start-up failure (SUF) indicator from firmware of the ONU (140).

5. The method (400) of claim 1, wherein the self-calibration routine comprises: Determining a maximum wavelength of the operating wavelength range (350) and a minimum wavelength of the operating wavelength range (350); as well as The injection current (212) of the DBR laser (200) is set to an operating injection current (212) within the operating wavelength range (350).

6. The method (400) of claim 5, wherein the operating injection current (212) comprises an average or median value of the operating wavelength range (350).

7. The method (400) of claim 1, wherein determining that the connection between the OLT (120) and the ONU (140) fails to meet the connection quality criteria (330) comprises receiving a loss of frame (LOF) indicator from firmware of the OLT (120).

8. The method (400) of claim 1, wherein determining that the connection between the OLT (120) and the ONU (140) fails to meet the connection quality criteria (330) comprises receiving a deactivate DACT indicator from firmware of the ONU (140).

9. The method (400) of claim 8, wherein determining that the connection satisfies the connection quality criterion (330) comprises determining that the ONU (140) has cleared the DACT indicator.

10. A system (100) for calibration of a laser transmitter, comprising: Data processing hardware (144); as well as Memory hardware (146) in communication with the data processing hardware (144), the memory hardware (146) storing instructions that, when executed on the data processing hardware (144), cause the data processing hardware (144) to perform operations including: Determining that a connection between an optical line terminal (OLT) (120) and an optical network unit (ONU) (140) fails to meet a connection quality criterion (330), the ONU (140) comprising a distributed Bragg reflector (DBR) laser (200); as well as A self-calibration routine is performed to determine an operating wavelength range (350) of the DBR laser (200) that maintains the connection between the OLT (120) and the ONU (140) and satisfies the connection quality criteria (330), the self-calibration routine comprising iteratively performing: Tuning the injection current (212) of the DBR laser (200) to adjust the communication wavelength of the ONU (140); determining whether the communication wavelength establishes or maintains a connection between the OLT (120) and the ONU (140); When the communication wavelength establishes or maintains a connection between the OLT (120) and the ONU (140), determining whether the connection satisfies the connection quality criterion (330); and When the connection satisfies the connection quality criterion (330), the operating wavelength range (350) of the DBR laser (200) is updated to include the communication wavelength.

11. The system (100) of claim 10, wherein the connection quality criteria (330) comprises satisfying at least one of: a packet loss threshold, a frame loss LOF indicator, a start failure SUF indicator, or a connection loss indicator.

12. The system (100) of claim 10, wherein determining that the connection between the OLT (120) and the ONU (140) fails to meet the connection quality criterion (330) comprises receiving a physical layer operations, administration, and maintenance (PLOAM) message (312) from the OLT (120) indicating that the connection quality criterion (330) fails to be met.

13. The system (100) of claim 10, wherein determining that the connection between the OLT (120) and the ONU (140) fails to meet the connection quality criteria (330) comprises receiving a loss of frame (LOF) indicator, a loss of signal (LOS) indicator, or a start-up failure (SUF) indicator from firmware of the ONU (140).

14. The system (100) of claim 10, wherein the self-calibration routine comprises: Determining a maximum wavelength of the operating wavelength range (350) and a minimum wavelength of the operating wavelength range (350); as well as The injection current (212) of the DBR laser (200) is set to an operating injection current (212) within the operating wavelength range (350).

15. The system (100) of claim 14, wherein the operational injection current (212) comprises an average or median value of the operating wavelength range (350).

16. The system (100) of claim 10, wherein determining that the connection between the OLT (120) and the ONU (140) fails to meet the connection quality criteria (330) comprises receiving a loss of frame (LOF) indicator from firmware of the OLT (120).

17. The system (100) of claim 10, wherein determining that the connection between the OLT (120) and the ONU (140) fails to meet the connection quality criteria (330) comprises receiving a deactivate DACT indicator from firmware of the ONU (140).

18. The system (100) of claim 17, wherein determining that the connection satisfies the connection quality criteria (330) comprises determining that the ONU (140) has cleared the DACT indicator.

19. A method (500) for calibrating a laser transmitter, comprising: Receiving a downstream connection (310) from an optical line terminal (OLT) (120) at data processing hardware (144) of an optical network unit (ONU) (140), the ONU (140) comprising a distributed Bragg reflector (DBR) laser (200); Attempting, by the data processing hardware (144), to establish an upstream connection (320) between the ONU (140) and the OLT (120); receiving a message (312) at the data processing hardware (144) of the ONU (140) to initiate calibration of the ONU (140) when the ONU (140) establishes an upstream connection (320) to the OLT (120), the message (312) being generated to indicate that the DBR laser (200) is operating outside of an operational state; as well as Tuning the DBR laser (200) to the operating state by adjusting an injection current (212) of the DBR laser (200) by the data processing hardware (144) of the ONU (140); wherein tuning the DBR laser (200) to the operating state comprises: adjusting the injection current (212) of the DBR laser (200) to a first injection current; Determining a first injection current (212) of the DBR laser (200) to establish an upstream connection (320) between the ONU (140) and the OLT (120); identifying the first injection current (212) as a first boundary of an operating window of an operating state of the DBR laser (200); adjusting the injection current (212) of the DBR laser (200) to a second injection current (212); Determining that a second injection current (212) of the DBR laser (200) fails to maintain or establish an upstream connection (320) between the ONU (140) and the OLT (120); identifying the second injection current (212) as a second boundary of an operating window of an operating state of the DBR laser (200); and An operating injection current (212) is supplied to the DBR laser (200), the operating injection current (212) being between the first injection current (212) and the second injection current (212).

20. The method (500) of claim 19, wherein the operational injection current (212) is an average or median value of the first injection current (212) and the second injection current (212).

21. The method (500) of claim 19, wherein adjusting an injection current (212) of the DBR laser (200) to the first injection current (212) comprises incrementally changing the injection current (212).

22. The method (500) of claim 19, wherein determining that the second injection current (212) of the DBR laser (200) fails to maintain or establish an upstream connection (320) between the ONU (140) and the OLT (120) comprises receiving a start-up failure (SUF) indicator or a deactivation (DACT) indicator at the ONU (140).

23. The method (500) of claim 19, further comprising initiating calibration of the ONU (140) by the data processing hardware (144) when the ONU (140) fails to establish an upstream connection (320) to the OLT (120).

24. The method (500) of any one of claims 19-23, further comprising, when the ONU (140) establishes an upstream connection (320) to the OLT (120), communicating data from the ONU (140) by the data processing hardware (144) at a bit error rate that satisfies a bit error threshold, the bit error threshold indicating an acceptable error level for data transmission through the ONU (140).

25. The method (500) of claim 24, wherein receiving a DACT indicator at the ONU (140) indicates a failure to meet the bit error threshold.

26. A system (100) for calibration of a laser transmitter, comprising: An optical network unit ONU (140), wherein the optical network unit ONU (140) comprises a distributed Bragg reflector DBR laser (200); data processing hardware (144); and Memory hardware (146) in communication with the data processing hardware (144), the memory hardware (146) storing instructions that, when executed on the data processing hardware (144), cause the data processing hardware (144) to perform operations including: Receiving a downstream connection (310) from an optical line terminal OLT (120) to the ONU (140); Attempting to establish an upstream connection (320) between the ONU (140) and the OLT (120); receiving a message (312) to initiate calibration of the ONU (140) when the ONU (140) establishes an upstream connection (320) to the OLT (120), the message (312) being generated to indicate that the DBR laser (200) is operating outside of an operational state; as well as tuning the DBR laser (200) to the operating state by adjusting an injection current (212) of the DBR laser (200); wherein tuning the DBR laser (200) to the operating state comprises: adjusting the injection current (212) of the DBR laser (200) to a first injection current; Determining a first injection current (212) of the DBR laser (200) to establish an upstream connection (320) between the ONU (140) and the OLT (120); identifying the first injection current (212) as a first boundary of an operating window of an operating state of the DBR laser (200); adjusting the injection current (212) of the DBR laser (200) to a second injection current (212); Determining that a second injection current (212) of the DBR laser (200) fails to maintain or establish an upstream connection (320) between the ONU (140) and the OLT (120); identifying the second injection current (212) as a second boundary of an operating window of an operating state of the DBR laser (200); and An operating injection current (212) is supplied to the DBR laser (200), the operating injection current (212) being between the first injection current (212) and the second injection current (212).

27. The system (100) of claim 26, wherein the operational injection current (212) is an average or median value of the first injection current (212) and the second injection current (212).

28. The system (100) of claim 26, wherein: Adjusting the injection current (212) of the DBR laser (200) to the first injection current (212) includes incrementally changing the injection current (212).

29. The system (100) of claim 26, wherein determining that the second injection current (212) of the DBR laser (200) fails to maintain or establish an upstream connection (320) between the ONU (140) and the OLT (120) comprises receiving a start-up failure (SUF) indicator or a deactivation (DACT) indicator at the ONU (140).

30. The system (100) of claim 26, wherein the operations further comprise initiating calibration of the ONU (140) when the ONU (140) fails to establish an upstream connection (320) to the OLT (120).

31. The system (100) of any one of claims 26-30, wherein the operations further include, when the ONU (140) establishes an upstream connection (320) to the OLT (120), communicating data from data processing hardware (144) of the ONU (140) at a bit error rate that satisfies a bit error threshold, the bit error threshold indicating an acceptable error level for data transmission through the ONU (140).

32. The system (100) of claim 31, wherein receiving a DACT indicator at the ONU (140) indicates a failure to meet the bit error threshold.

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