Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
  • G02B6/4201—Packages, e.g. shape, construction, internal or external details
  • G02B6/4246—Bidirectionally operating package structures
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
  • G02B6/4201—Packages, e.g. shape, construction, internal or external details
  • G02B6/4266—Thermal aspects, temperature control or temperature monitoring
  • G02B6/4268—Cooling
  • G02B6/4271—Cooling with thermo electric cooling
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
  • G02B6/4201—Packages, e.g. shape, construction, internal or external details
  • G02B6/4266—Thermal aspects, temperature control or temperature monitoring
  • G02B6/4273—Thermal aspects, temperature control or temperature monitoring with heat insulation means to thermally decouple or restrain the heat from spreading
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
  • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
  • G02B6/12007—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer
  • G02B6/12009—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer comprising arrayed waveguide grating [AWG] devices, i.e. with a phased array of waveguides
  • G02B6/12019—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer comprising arrayed waveguide grating [AWG] devices, i.e. with a phased array of waveguides characterised by the optical interconnection to or from the AWG devices, e.g. integration or coupling with lasers or photodiodes
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
  • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
  • G02B6/12007—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer
  • G02B6/12009—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer comprising arrayed waveguide grating [AWG] devices, i.e. with a phased array of waveguides
  • G02B6/12026—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer comprising arrayed waveguide grating [AWG] devices, i.e. with a phased array of waveguides characterised by means for reducing the temperature dependence
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04J—MULTIPLEX COMMUNICATION
  • H04J14/00—Optical multiplex systems
  • H04J14/02—Wavelength-division multiplex systems
  • H04J14/0278—WDM optical network architectures
  • H04J14/0282—WDM tree architectures

Definitions

• the present disclosure relates to multi-channel optical transmitters or transceivers and more particularly, to a thermally shielded multi-channel transmitter optical subassembly (TOSA).
• TOSA thermally shielded multi-channel transmitter optical subassembly
• Optical communications networks at one time, were generally "point to point" type networks including a transmitter and a receiver connected by an optical fiber. Such networks are relatively easy to construct but deploy many fibers to connect multiple users. As the number of subscribers connected to the network increases and the fiber count increases rapidly, deploying and managing many fibers becomes complex and expensive.
• a passive optical network addresses this problem by using a single "trunk" fiber from a transmitting end of the network, such as an optical line terminal (OLT), to a remote branching point, which may be up to 20 km or more.
• OLT optical line terminal
• One challenge in developing such a PON is utilizing the capacity in the trunk fiber efficiently in order to transmit the maximum possible amount of information on the trunk fiber.
• Fiber optic communications networks may increase the amount of information carried on a single optical fiber by multiplexing different optical signals on different wavelengths using wavelength division multiplexing (WDM).
• WDM wavelength division multiplexing
• the single trunk fiber carries optical signals at multiple channel wavelengths to and from the optical branching point and the branching point provides a simple routing function by directing signals of different wavelengths to and from individual subscribers.
• each subscriber may be assigned one or more of the channel wavelengths on which to send and/or receive data.
• the OLT in a WDM-PON may include a multi-channel transmitter optical subassembly (TOSA) and a multi-channel receiver optical subassembly (ROSA).
• TOSA transmitter optical subassembly
• ROSA receiver optical subassembly
• a TOSA includes an array of lasers optically coupled to an arrayed waveguide grating (AWG) to combine multiple optical signals at multiple channel wavelengths.
• AWG arrayed waveguide grating
• the desired accuracy or precision of the wavelengths in a WDM-PON often depends on the number and spacing of the channel wavelengths and may be controlled in the TOSA by controlling temperature.
• OLT transceiver modules provide temperature control of the laser array and AWG in a relatively small space and with relatively low power consumption to prevent external heat from adversely affecting the laser wavelengths.
• the temperature of each laser may be affected by adjacent lasers as well as the thermal air flow throughout the TOSA.
• FIG. 1 is a functional block diagram of a wavelength division multiplexed (WDM) passive optical network (PON) including at least one multi-channel optical transceiver, consistent with embodiments of the present disclosure.
• WDM wavelength division multiplexed
• PON passive optical network
• FIG. 2 is an exploded view of a multi-channel optical transceiver including a thermally shielded multi-channel TOSA, consistent with an embodiment of the present disclosure.
• HG. 4 is an end perspective view of a multi-channel TOSA including an array of thermally shielded lasers, consistent with an embodiment of the present disclosure.
• FIG. 5 is a side perspective, cross-sectional view of shown in FIG. 4 illustrating one of the thermally shielded lasers.
• HG. 6 is an enlarged perspective view of the multi -channel TOSA and the thermally shielded laser shown in FIG. 5.
• HG. 7 is a side view of the multi-channel TOSA and the thermally shielded laser shown in FIG. 6.
• FIGS. 8 and 9 are top and perspective views, respectively, of one embodiment of a thermally shielded laser.
• FIG. 10 is a perspective view of the laser thermal shield used in the thermally shielded laser shown in FIGS. 8 and 9.
• FIG. 11 is top perspective view of a multi-channel TOSA including an array of thermally shielded lasers, consistent with another embodiment of the present disclosure.
• FIG. 12 is an enlarged, partially cross-sectional view of the array of thermally shielded lasers in the multi-channel TOSA shown in FIG. 11.
• FIG. 13 is a side cross-sectional view of a thermally shielded laser in the multichannel TOSA shown in FIG. 11.
• FIG. 14 is a top cross-sectional view of the thermally shielded laser taken along line 13-13 in FIG. 13.
• FIG. 15 is a bottom plan view of the plurality of laser thermal shields used in the multi-channel TOSA shown in FIG. 11.
• FIG. 16 is a back end view of the laser thermal shields shown in FIG. 15.
• FIG. 17 is a front end view of the laser thermal shields shown in FIG. 15.
• a thermally shielded multi-channel transmitter optical subassembly may be used in a multi-channel optical transceiver.
• the multi-channel TOSA generally includes an array of lasers optically coupled to an arrayed waveguide grating (AWG) to combine multiple optical signals at different channel wavelengths.
• a plurality of laser array thermal shields are thermally coupled to a temperature control device, such as a thermoelectric cooler (TEC), and thermally shield the respective lasers in the laser array in separate thermally shielded compartments.
• TEC thermoelectric cooler
• Each of the lasers may also be individually thermally controlled to provide a desired wavelength, for example, using a heater and/or cooler located in each thermally shielded compartment.
• the optical transceiver may be used in a wavelength division multiplexed (WDM) optical system, for example, in an optical line terminal (OLT) in a WDM passive optical network (PON).
• WDM wavelength division multiplexed
• OLT optical line terminal
• PON WDM passive optical
• channel wavelengths refer to the wavelengths associated with optical channels and may include a specified wavelength band around a center wavelength.
• the channel wavelengths may be defined by an International Telecommunication (ITU) standard such as the ITU-T dense wavelength division
• thermoally coupled refers to a direct or indirect connection or contact between two components resulting in heat being conducted from one component to the other component and “thermally isolated” refers to an
• thermally isolated multi-channel TOSA for example, heat external to the TOSA is prevented from being conducted to one or more components in the TOSA.
• thermally shielded refers to an arrangement that prevents heat from being transferred by convection or radiation to the shielded component. Thermally isolated and thermally shielded do not necessarily require an arrangement to prevent all heat from being conducted or transferred.
• the OLT 110 may be located at a central office of the WDM-PON 100, and the ONUs 112-1 to 112-n may be located in homes, businesses or other types of subscriber location or premises.
• a branching point 113 e.g., a remote node
• the branching point 113 may include one or more passive coupling devices such as a splitter or optical multiplexer/demultiplexer.
• the ONUs 112-1 to 112-n may be located about 20 km or less from the OLT 110.
• the WDM-PON 100 may also include additional nodes or network devices, such as Ethernet PON (EPON) or Gigabit PON (GPON) nodes or devices, coupled between the branching point 113 and ONUs 112-1 to 112-n at different locations or premises.
• additional nodes or network devices such as Ethernet PON (EPON) or Gigabit PON (GPON) nodes or devices, coupled between the branching point 113 and ONUs 112-1 to 112-n at different locations or premises.
• Ethernet PON EPON
• GPON Gigabit PON
• One application of the WDM-PON 100 is to provide fiber-to-the-home (FTTH) or fiber-to-the- premises (FTTP) capable of delivering voice, data, and/or video services across a common platform.
• FTTH fiber-to-the-home
• FTTP fiber-to-the- premises
• the central office may be coupled to one or more sources or networks providing the voice, data and/or video.
• different ONUs 112-1 to 112-n may be assigned different channel wavelengths for transmitting and receiving optical signals.
• the ONUs 112-1 to 112-n may be assigned different channel wavelengths for transmitting and receiving optical signals.
• the ONUs 112-1 to 112-n may be assigned different channel wavelengths for transmitting and receiving optical signals.
• WDM-PON 100 may use different wavelength bands for transmission of downstream and upstream optical signals relative to the OLT 110 to avoid interference between the received signal and back reflected transmission signal on the same fiber.
• the OLT 110 may be used for downstream transmissions from the OLT 110 and the C-band (e.g., about 1530 to 1565 nm) may be used for upstream transmissions to the
• the upstream and/or downstream channel wavelengths may generally correspond to the ITU grid.
• the upstream wavelengths may be aligned with the 100 GHz
• ITU grid and the downstream wavelengths may be slightly offset from the 100 GHz ITU grid.
• the ONUs 112-1 to 112-n may thus be assigned different channel wavelengths within the L-band and within the C-band.
• Transceivers or receivers located within the ONUs 112-1 to 112-n may be configured to receive an optical signal on at least one channel wavelength in the L-band (e.g., ⁇ , ⁇ , ⁇ ⁇ ⁇ ) ⁇
• 1 to 112- n may be configured to transmit an optical signal on at least one channel wavelength in the C-band (e.g., ⁇ , ⁇ 2 , ⁇ ⁇ ⁇ ⁇ ⁇
• Other wavelengths and wavelength bands are also within the scope of the system and method described herein.
• the branching point 113 may demultiplex a downstream WDM optical signal (e.g., ⁇ ) ⁇ ⁇ - ⁇ ⁇ ) from the OLT 110 for transmission of the separate channel wavelengths to the respective ONUs 112-1 to 112-n.
• the branching point 113 may provide the downstream WDM optical signal to each of the ONUs 112-1 to 112-n and each of the ONUs
• the branching point 113 also combines or multiplexes the upstream optical signals from the respective ONUs 112-1 to 112-n for transmission as an upstream WDM optical signal (e.g., ⁇ 2 , ⁇ ⁇ ⁇ over the trunk optical path 114 to the OLT 110.
• an upstream WDM optical signal e.g., ⁇ 2 , ⁇ ⁇ ⁇ over the trunk optical path 114 to the OLT 110.
• One embodiment of the ONU 112-1 includes a laser 116, such as a laser diode, for transmitting an optical signal at the assigned upstream channel wavelength kci) and a photodetector 118, such as a photodiode, for receiving an optical signal at the assigned downstream channel wavelength ( ⁇ ).
• the laser 116 may include a tunable laser configured to be tuned to the assigned channel wavelength.
• This embodiment of the ONU 112- 1 may also include a diplexer 117 coupled to the laser 116 and the photodetector 118 and a C + L band filter 119 coupled to the diplexer 117, which allow the L-band channel wavelength ( ⁇ ) to be received by the ONU 112-1 and the C-band channel wavelength ( ⁇ ) to be transmitted by the ONU 112-1.
• the OLT 110 may be configured to generate multiple optical signals at different channel wavelengths (e.g., ⁇ , ⁇ , . . . ⁇ ) and to combine the optical signals into the downstream WDM optical signal carried on the trunk optical fiber or path 114.
• Each of the OLT multi-channel optical transceivers 102a, 102b may include a multi-channel transmitter optical subassembly (TOSA) 120 for generating and combining the optical signals at the multiple channel wavelengths.
• TOSA transmitter optical subassembly
• the OLT 110 may also be configured to separate optical signals at different channel wavelengths (e.g., ⁇ , ⁇ 2 , ⁇ ⁇ ⁇ from an upstream WDM optical signal carried on the trunk path 114 and to receive the separated optical signals.
• Each of the OLT multi-channel optical transceivers 102a, 102b may thus include a multi-channel receiver optical subassembly (ROSA) 130 for separating and receiving the optical signals at multiple channel wavelengths.
• ROSA
• One embodiment of the multi-channel TOSA 120 includes an array of lasers 122, such as laser diodes, which may be modulated by respective RF data signals (TX_D1 to
• the OLT 110 further includes a multiplexer 104 for multiplexing the multiplexed optical signal from the multi-channel TOSA 120 in the multichannel transceiver 102a with a multiplexed optical signal from a multi-channel TOSA in the other multi-channel transceiver 102b to produce the downstream aggregate WDM optical signal.
• a multiplexer 104 for multiplexing the multiplexed optical signal from the multi-channel TOSA 120 in the multichannel transceiver 102a with a multiplexed optical signal from a multi-channel TOSA in the other multi-channel transceiver 102b to produce the downstream aggregate WDM optical signal.
• the lasers 122 may include, for example, distributed feedback (DFB) lasers with diffraction gratings that provide optical feedback for the laser and that alter the lasing wavelength in response to temperature changes.
• the TOSA 120 may also include a temperature control system for controlling temperature of the lasers 122 and/or the multiplexer 124 to maintain a desired wavelength precision or accuracy.
• Each of the lasers 122 may also be thermally shielded and/or thermally isolated to maintain a desired temperature of the laser and a desired wavelength precision or accuracy, as described in greater detail below.
• One embodiment of the multi-channel ROSA 130 includes a demultiplexer 132 for separating the respective upstream channel wavelengths (e.g., ⁇ , ⁇ 2 , ⁇ ⁇ ⁇ ⁇ ⁇ An array of photodetectors 134, such as photodiodes, detects the optical signals at the respective separated upstream channel wavelengths and provides the received data signals (RX_D1 to
• the OLT 110 further includes a demultiplexer 106 for demultiplexing the upstream WDM optical signal into first and second WDM optical signals provided to the respective multi-channel ROSA in each of the transceivers 102a,
• the OLT 110 also includes a diplexer 108 between the trunk path 114 and the multiplexer 104 and the demultiplexer 106 such that the trunk path 114 carries both the upstream and the downstream channel wavelengths.
• the transceivers 102a, 102b may also include other components, such as laser drivers, transimpedance amplifiers (TIAs), and control interfaces, used for transmitting and receiving optical signals.
• each of the multi-channel optical transceivers 102a, 102b may be configured to transmit and receive 16 channels such that the WDM-PON 100 supports 32 downstream L-band channel wavelengths and 32 upstream C-band channel wavelengths.
• the downstream L-band link between the OLT transceivers 102a, 102b and the ONUs 112-1 to 112-n may support a power budget of at least about 26 dB and the upstream C-band link between the ONUs 112-1 to 112-n and the OLT transceivers 102a, 102b may support a power budget of at least about 23 dB.
• the WDM-PON 100 may operate at 1.25 Gbaud using 8B/10B encoded on-off keying as the modulation scheme. Other data rates and modulation schemes may also be used.
• the upstream and downstream channel wavelengths may span a range of channel wavelengths on the 100 GHz ITU grid.
• Each of the transceivers 102a, 102b may cover 16 channel wavelengths in the L-band for the TOSA and 16 channel wavelengths in the C-band for the ROSA such that the transceivers 102a, 102b together cover 32 channels.
• the multiplexer 104 may combine 16 channels from one transceiver 102a with 16 channels from the other transceiver 102b, and the demultiplexer 106 may separate a 32 channel WDM optical signal into two 16 channel WDM optical signals.
• the range of channel wavelengths may skip channels (e.g., 2 channels) in the middle of the range.
• the desired wavelength precision or accuracy is + 0.05 nm
• the desired operating temperature range is between -5 and 70 °C
• the desired power dissipation is about 16.0 W.
• a multi-channel optical transceiver module 202 including a thermally shielded and/or isolated multi-channel TOSA 220 is shown and described in greater detail.
• multiple multi-channel transceiver modules may be used in an OLT of a WDM-PON to cover a desired channel range.
• the transceiver module 202 and the multi-channel TOSA 220 within the transceiver module 202 may thus be designed to have a relatively small form factor with minimal space.
• the multichannel optical transceiver module 202 generally provides an optical input and output at one end 204 and electrical input and output at another end 206.
• the transceiver module 202 includes a transceiver housing 210 containing the multi-channel TOSA 220, a multi-channel ROSA 230, and a dual fiber type direct link adapter 213 directly linked to the TOSA 220 and the ROSA 230 for providing the optical input and output.
• the dual fiber type direct link adapter 213 is also configured to receive pluggable optical connectors, such as LC connectors (not shown), to connect the TOSA 220 and ROSA 230, respectively, to fiber optic cables (not shown).
• pluggable optical connectors such as LC connectors (not shown)
• the adapter 213 establishes an optical coupling between the TOSA 220 and the ROSA 230 and the respective optical fibers in the fiber-optic cables, which carry the optical signals to and from the transceiver.
• the multi-channel TOSA 220 includes an array of lasers (not shown in FIGS. 2 and 3) coupled to an AWG 225.
• a temperature control system may control the temperature of the laser array and/or the AWG 225 using the same temperature control device.
• Each of the lasers is also thermally shielded from heat within the TOSA 220 and may be thermally isolated from heat external to the TOSA 220.
• the temperature of each of the lasers in the laser array may also be controlled individually, for example, to provide a desired wavelength with a desired wavelength precision or accuracy. In one example, the temperature of each laser is maintained within + 0.5°C in the operating range between -5 and 70 °C to maintain a wavelength precision or accuracy of about + 0.05 nm.
• the transceiver module 202 may also include one or more printed circuit boards 208 coupled to the TOSA 220 and/or ROSA 230.
• the printed circuit board(s) 208 may include circuitry and electronic components such as laser drivers, transimpedance amplifiers (TIAs), and control interfaces.
• the TOSA 220 is coupled to conductive leads 224 for carrying the electronic signals including the data to be transmitted by the TOSA 220.
• the ROSA 230 is coupled to the conductive leads 234 for carrying the electronic signals including the data received by the ROSA 230.
• a top housing portion 212 encloses the TOSA 220, the ROSA 230, the adapter 250, the optical fibers 222, 232, and other components within the housing 210.
• the transceiver housing 210 may have a width of less than about 55 mm, a length of less than about 130 mm, and a height of less than about 10 mm. More specifically, one example of a transceiver housing 210 may have a width of 54.6 mm, a length of 110 mm, and a height of about 9.8 mm.
• the thermally shielded multi-channel TOSA 220 has a width, a height and length capable of fitting within the transceiver housing 210.
• Each of the lasers 226-1 to 226-n in the array may be a distributed feedback (DFB) laser capable of altering lasing wavelengths in response to temperature changes and may be thermally shielded, as described in greater detail below.
• the lasers 226-1 to 226-n may be optically coupled to the AWG 225, for example, using low bending loss optical fibers (not shown).
• Each laser 226-1 may be provided as a laser package including, but not limited to, a laser diode chip mounted on a laser mounting structure or sub- mount.
• the laser package may also include optical components, such as a lens for optically coupling the laser light into a respective one of the optical fibers, and/or optoelectronic components, such as a monitor photodiode.
• the AWG 225 may include an AWG chip such as the type used for WDM, Coarse WDM (CWDM), or Dense (DWDM) multiplexing or demultiplexing.
• the array of lasers 226- 1 to 226-n are supported on a laser array tray 240 and the AWG 225 is supported on an AWG tray 242.
• Both the laser array tray 240 and the AWG tray 242 may be thermally coupled to the same temperature control device 260 such that the temperature control device 260, the laser array tray 240 and the AWG tray 242 provide a temperature control system for the TOSA within a relatively small space.
• the temperature control device 260 may be a thermoelectric cooler, such as a Peltier device, for cooling the array of lasers 226-1 to 226-n and the AWG 225.
• the AWG tray 242 supports the AWG 225 above the lasers 226- 1 to 226-n.
• the laser array tray 240 may be a relatively flat plate that fits between the side portions 246, 248 such that both the laser array tray 240 and the side portions 246, 248 of the AWG tray 242 are separately thermally coupled to the temperature control device 260 (e.g., to the cold side of a TEC).
• the laser array tray 240 and the side portions 246, 248 of the AWG tray 242 may each directly contact the temperature control device 260 or may be thermally coupled through another thermally conductive material. Because a larger surface area of the laser array tray 240 is thermally coupled to the temperature control device 260, the temperature of the lasers 226-1 to 226-n may be controlled more precisely.
• Both of the trays 240, 242 may be made of a thermally conductive material having a thermal conductivity greater than 60 W/(m- K) and more specifically greater than 80 W/(m- K).
• the trays 240, 242 may be made, for example of copper or zinc. At least a portion of the trays 240, 242 may also be gold plated, for example, to facilitate soldering to the trays 240, 242.
• the laser array tray 240 is made of A1N with a thermal conductivity of about 170 W/(m- K) and the AWG tray 242 is made of copper with Au plating and having a thermal conductivity of greater than 300 W/(m- K).
• the thermal isolation bar 270 may include multiple sections and/or may extend across only a portion of the TOSA 220.
• Each of the lasers 226 (and/or other optoelectronic components) is wire bonded with at least one wire 272 to a conductive pad 271 on the thermal isolation bar 270.
• a single laser 226 is shown with a single wire 272, multiple wires 272 may be used to wire bond each of the lasers (e.g., lasers 226-1 to 226-n shown in FIG. 4) to separate conductive pads on the thermal isolation bar 270.
• the thermal isolation bar 270 is shown having a rectangular shape, other shapes and configurations are possible.
• the thermal isolation bar 270 provides an electrical connection between the lasers 226 and external circuitry, such as the printed circuit board 208. As shown, for example, the thermal isolation bar 270 is wire bonded with wires 274 to conductive pads 280 located on a TOSA housing portion 282. The conductive pads 280 are electrically connected to circuitry, for example, via conductive traces or paths 284 extending through the housing portion 282 and via the conductive leads 224 (see FIG. 5). Multiple wires 274 may be used between respective conductive pads 271 on the thermal isolation bar 270 and the conductive pads 280 on the housing portion 282 to provide multiple electrical connections between each of the lasers in a laser array and the circuitry. Although a specific arrangement providing an electrical connection to external circuitry is illustrated and described, other arrangements may also provide an electrical connection to the circuitry.
• the temperature of the thermal isolation bar 270 may be controlled (e.g., by cooling or heating) to prevent heat from being conducted from the pads 280, which are linked to the external environment, to the lasers 226.
• the thermal isolation bar 270 thus isolates the lasers 226 from the external heat generated in the environment external to the TOSA 220 while allowing the lasers 226 to be electrically connected to circuitry outside of the TOSA 220.
• the thermal isolation bar 270 may be made of a thermally conductive material having a thermal conductivity greater than 60 W/(m- K), such as, for example, aluminum nitride (A1N).
• the conductive traces or paths on the thermal isolation bar 270 may include gold, for example, to facilitate solderability.
• the laser array thermal shield 250 may be made of a thermally conductive material having a thermal conductivity greater than 60 W/(m- K) and more specifically greater than 80 W/(m- K) and, for example, about 160 W/(m- K).
• the laser array thermal shield 440 may be made, for example, from copper tungsten and may also be gold plated, for example, to facilitate soldering. Other thermally conductive materials may also be used.
• the laser 226 includes a laser diode chip 227 (e.g., a DFB laser diode chip) mounted on a sub-mount 229.
• the thermally shielded compartment 252 is configured to receive the sub-mount 229 between the walls 251.
• a monitor photodiode 228 may also be mounted on the sub-mount 229, for example, to monitor light emitted from the laser diode chip 227.
• a heater 264 such as a resistor, may be located adjacent the laser diode chip 227 to provide independent control of the temperature of the laser diode chip 227 and thus the wavelength of the emitted laser light.
• the temperature control device 260 may be used to maintain a consistent baseline temperature of the array of lasers 226- 1 to 226-n and the heaters 264 may be used to raise the temperature of each of the lasers 226 individually and independently above this baseline temperature to change the wavelength.
• the thermal shield 250 facilitates this independent temperature control of each of the lasers by preventing heat from outside of the thermally shielded compartment 252 from affecting the laser diode chip 227.
• other temperature control devices such as a micro TEC, may be used to provide the individual and independent temperature control of the laser diode chip 227.
• the illustrated embodiment of the laser thermal shield 250 is also configured to receive a lens 223, for example, to focus emitted laser light into an optical fiber or waveguide. As shown, the laser thermal shield 250 also receives and supports the lens such that the laser diode chip 227 is aligned with the lens 223. Although the illustrated embodiment shows the laser thermal shield 250 with a particular shape, other shapes and configurations are also possible. In other embodiments, for example, the laser thermal shield 250 may be closed at the top.
• FIGS. 11-17 illustrate another embodiment of a thermally shielded multi-channel
• a plurality of laser thermal shields 1150 are integrated as a one piece and define a plurality of thermally shielded compartments 1152 that enclose the lasers 1126 on the top and sides.
• the laser thermal shields 1150 also define windows 1156 that allow each of the lasers to emit laser light out of the compartments 1152.
• the lasers 1126 may include, for example, an array of DFB lasers capable of altering lasing wavelengths in response to temperature changes.
• the laser thermal shields 1150 provide thermal shielding for each of the lasers 1126 and thus may prevent heat from outside each of the thermally shielded compartments 1152 (e.g., from other lasers or from thermal air flow in the TOSA 1120) from affecting the lasers within the compartments 1152.
• the thermally shielded multi-channel TOSA 1120 also includes a temperature control device 1160 thermally coupled to the array of lasers 1126 and the laser thermal shields 1150.
• the temperature control device 1160 may be a thermoelectric cooler, such as a Peltier device, for cooling the laser array 1126.
• a thermally conductive base plate 1162 is located on the temperature control device 1160 and the lasers 1126 are mounted on the base plate 1162. At least a portion of the laser thermal shields 1150 may also contact the base plate 1162 to provide the thermal coupling between the temperature control device 1160 and the laser thermal shields 1150.
• the temperature control device 1160 may thus maintain a consistent temperature for each of the lasers 1126 and for each of the laser thermal shields 1150.
• the temperature control device 1160 maintains a temperature of the base plate 1162 at about 40°C.
• a temperature monitor such as a thermistor, may be used to monitor the temperature of the base plate 1162 such that the base plate 1162 is maintained at the desired temperature.
• Each of the thermally shielded compartments 1152 may also enclose one or more temperature control devices for independently controlling the temperature of each of the lasers 1126, as will be described in greater detail below.
• the laser thermal shield 1150 facilitates this independent temperature control and allows the temperature to be maintained within a desired range (e.g., within + 0.5°C of a target temperature).
• the laser thermal shields 1150 may be made of a thermally conductive material having a thermal conductivity greater than 60 W/(m- K) and more specifically greater than 80 W/(m- K) and, for example, about 160 W/(m- K).
• the laser thermal shields 1150 may be made, for example, from copper tungsten. Other thermally conductive materials may also be used.
• the base plate 1162 may also be made of a thermally conductive material having a thermal conductivity greater than greater than 60 W/(m- K) and more specifically greater than 80 WV(m- K).
• the lasers 1126 may be optically coupled to an AWG (not shown in FIGS. 11 and 12), which is supported above the laser array on an AWG tray, for example, as described above.
• the example embodiment shows a sixteen (16) channel TOSA with sixteen (16) lasers in the laser array 1126 and sixteen corresponding thermally shielded compartments 1152; however, other numbers of channels, lasers and shielded compartments are possible.
• each of the lasers 1126 includes a laser diode chip 1127 (e.g., a DFB laser diode chip) mounted on a sub-mount 1129 located in the thermally shielded compartment 1152.
• a photodiode 1128 may also be mounted on the sub-mount 1129 for monitoring the light emitted from the laser diode chip 1127.
• the laser diode chip 1127 is aligned with the window 1156 such that the laser light emitted from the laser diode chip 1127 passes through the window 1156.
• Other optical components may also be used to couple the laser light into optical fibers or waveguides (not shown).
• a lens 1123 may be aligned with the window 1156 to focus and optically couple the emitted laser light into an optical fiber or waveguide (not shown).
• FIGS. 13 and 14 show the thermally shielded compartment 1152 in greater detail.
• Each thermally shielded compartment 1152 may be formed by a front wall 1153, a rear wall 1154, side walls 1151 and a top portion 1155, which enclose the laser sub-mount 1129.
• One or more of the thermal shield walls 1153, 1154, 1151 also extend to the base plate 1162, which thermally couples the respective thermal shield 1150 to the temperature control device 1160.
• at least the side walls 1151 between the thermally shielded compartments 1152 contact the base plate 1162 to provide thermal isolation walls between each of the laser sub-mounts 1129, which shield and/or isolate each of the laser diode chips 1127 in the compartments 1152.
• At least one temperature control device may be located in each of the thermally shielded compartments 1152 to provide individual and independent control of the temperature of each of the laser diode chips 1127.
• the temperature control device is a micro thermoelectric cooler (TEC) 1166 located below the laser diode chip 1127 and thermally coupled to the laser sub-mount 1129.
• the temperature control device is a heater 1164, such as a resistor, located beside the laser diode chip 1127 on the sub-mount 1129.
• the micro TEC 1166 and/or heater 1164 allow the temperature of the laser diode chip 1127 to be controlled independently of other laser diode chips.
• a thermal isolation member 1170 extends partially into the thermally shielded compartment 1152 to provide an electrical connection from the laser diode chip 1127 (and other components) to external circuitry (e.g., outside the TOSA).
• the thermal isolation member 1170 is thermally coupled to the temperature control device 1160 (e.g., via the base plate 1162) such that the laser diode chip 1127 (and other electrically connected components) may be thermally isolated from the external environment.
• the laser diode chip 1127 is wire bonded with at least one wire 1172 to a conductive pad 1172 on the thermal isolation member 1170.
• a single wire 1172 is shown coupling the laser diode chip 1127 to the thermal isolation member 1170, multiple wires may be used to bond other electronic or optoelectronic components in the thermally shielded compartment 1152 to separate conductive pads on the thermal isolation member 1170.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Optical Couplings Of Light Guides (AREA)
• Semiconductor Lasers (AREA)

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• 2014
  • 2014-02-04 CN CN201480011827.0A patent/CN105340204B/zh active Active
  • 2014-02-04 EP EP14749420.7A patent/EP2954628A4/en not_active Withdrawn
  • 2014-02-04 WO PCT/US2014/014607 patent/WO2014123866A1/en active Application Filing

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