Multichannel receiver optical subassembly with improved sensitivity

Patent metadata

Field	Value
Publication number	US-9847434-B2
Application number	US-201514665639-A
Country	US
Kind code	B2
Filing date	Mar 23, 2015
Priority date	Mar 23, 2015
Publication date	Dec 19, 2017
Grant date	Dec 19, 2017

Abstract

A multi-channel receiver optical subassembly (ROSA) such as an arrayed waveguide grating (AWG), with outputs directly optically coupled to respective photodetectors such as photodiodes. In one embodiment, the photodetectors are mounted on a photodetector mounting bar that includes a multiple conductive photodetector pads (PD pads). Each of the PD pads may be configured to receive a photodetector, and the PD pads are electrically isolated from ground such that the photodetectors are floating. The photodetector bar further includes multiple conductive transimpedance amplifier pads (TIA pads). Each of the TIA pads may be configured to receive a TIA, associated with one of the photodetectors, and to be electrically coupled to one or more ground ports of the TIA. The TIA pads are electrically connected to a common ground shared be each of said TIAs.

First claim

What is claimed is:

1. A photodetector mounting bar comprising:
a mounting surface;
a first plurality of transversely spaced conductive paths extending on said mounting surface, said first plurality of conductive paths extending longitudinally from a first side of said mounting surface;
a second plurality of transversely spaced conductive paths extending on said mounting surface, said second plurality of conductive paths extending longitudinally from said first side of said mounting surface, wherein said second plurality of conductive paths are positioned between two conductive paths of said first plurality of conductive paths;
a conductive photodetector pad (PD pad), wherein said PD pad is electrically isolated from ground; and
a conductive transimpedance amplifier pad (TIA pad), said TIA pad electrically connected to said ground, wherein said TIA pad is positioned between two conductive paths of said first plurality of conductive paths and is positioned between said PD pad and at least one conductive path of said second plurality of conductive paths.

2. The photodetector mounting bar of claim 1 , further comprising a photodetector electrically connected to said PD pad and a transimpedance amplifier (TIA) electrically connected to said TIA pad, wherein a cathode of said photodetector and an anode of said photodetector are electrically coupled to said TIA by wire bonding.

3. The photodetector mounting bar of claim 2 , wherein said wire bonding is less than 0.5 mm in length.

4. The photodetector mounting bar of claim 2 , wherein said photodetector is a PIN photodiode.

5. The photodetector mounting bar of claim 1 , further comprising 16 of said PD pads disposed on a long axis of said mounting bar over a length of less than 25 mm.

6. The photodetector mounting bar of claim 5 , wherein a pitch of said PD pads is less than 1.5 mm.

7. The photodetector mounting bar of claim 1 , wherein said TIA pad comprises a surface area of at least 1 square mm.

8. A multi-channel receiver optical subassembly (ROSA) comprising:
a ROSA housing;
an optical demultiplexer located in said ROSA housing, said optical demultiplexer including multiple optical outputs corresponding to multiple channels, said optical demultiplexer configured to receive a wavelength division multiplexed (WDM) optical signal on multiple channel wavelengths and to demultiplex said WDM optical signal to produce demultiplexed optical signals on said multiple channel wavelengths, respectively; and
a photodetector mounting bar having a mounting surface, said photodetector mounting bar located in said ROSA housing and said mounting surface of said photodetector mounting bar extending transverse to said optical outputs of said optical demultiplexer, wherein said mounting surface comprises:
a first plurality of conductive paths extending from a first side of said mounting surface;
a second plurality of conductive paths extending from said first side of said mounting surface, said second plurality of conductive paths being positioned between two conductive paths of said first plurality of conductive paths, wherein a length of said second plurality of conductive paths measures less than a length of said first plurality of conductive paths;
a plurality of photodetectors electrically isolated from ground such that said photodetectors are at a floating ground, said photodetectors being aligned with and optically coupled to said multiple optical outputs, respectively, of said optical demultiplexer; and
a plurality of transimpedance amplifiers (TIAs) associated with a respective one of said photodetectors and electrically coupled to a common ground shared by each of said TIAs.

9. The multi-channel ROSA of claim 8 , said photodetector mounting bar further comprising a plurality of conductive signal pads, each of said signal pads configured to be wire bonded to one or more signal ports of said TIAs.

10. The multi-channel ROSA of claim 9 , wherein said signal ports include a power port, a positive differential voltage output port, a negative differential voltage output port and a Received Signal Strength Indicator (RSSI) port.

11. The multi-channel ROSA of claim 8 , wherein a cathode and an anode of a respective photodetector is electrically coupled to a respective TIA by wire bonding.

12. The multi-channel ROSA of claim 11 , wherein said wire bonding is less than 0.5 mm in length.

13. The multi-channel ROSA of claim 8 , wherein said photodetectors are PIN photodiodes.

14. The multi-channel ROSA of claim 8 , wherein said optical demultiplexer includes an arrayed waveguide grating (AWG).

15. The multi-channel ROSA of claim 8 , wherein said mounting surface of said photodetector mounting bar further comprises:
a plurality of conductive photodetector pads (PD pads), wherein said PD pads are electrically isolated from ground and electrically connected to a respective photodetector; and
a plurality of conductive TIA pads, each of said TIA pads electrically connected to said common ground and to a respective TIA, wherein at least one of said TIA pads is positioned between two conductive paths of said first plurality of conductive paths and is positioned between at least one of said plurality of PD pads and at least one conductive path of said second plurality of conductive paths.

16. The multi-channel ROSA of claim 15 , wherein 16 of said PD pads are disposed on a long axis of said mounting bar over a length of less than 25 mm.

17. The multi-channel ROSA of claim 16 , wherein a pitch of said PD pads is less than 1.5 mm.

18. The multi-channel ROSA of claim 15 , wherein said TIA pads comprise a surface area of at least 1 square mm.

19. A multi-channel optical transceiver module comprising:
a transceiver housing having a transceiver optical connection end and a transceiver electrical connection end, said transceiver optical connection end of said transceiver housing being configured to provide an optical connection and said transceiver electrical connection end of said transceiver housing being configured to provide an electrical connection;
a circuit board located in said transceiver housing, wherein said circuit board includes RF inputs located proximate said transceiver electrical connection end of said transceiver housing;
a multi-channel transmitter optical subassembly (TOSA) located in said transceiver housing and electrically connected to said circuit board, said TOSA being configured to transmit a wavelength division multiplexed (WDM) optical signal on multiple channel wavelengths; and
a multi-channel receiver optical subassembly (ROSA) located in said transceiver housing and electrically connected to said circuit board, said ROSA being configured to receive a wavelength division multiplexed (WDM) optical signal on multiple channel wavelengths, wherein said ROSA comprises:
an optical demultiplexer including multiple optical outputs corresponding to multiple channels, said optical demultiplexer configured to receive a wavelength division multiplexed (WDM) optical signal on multiple channel wavelengths and to demultiplex said WDM optical signal to produce demultiplexed optical signals on said multiple channel wavelengths, respectively; and
a photodetector mounting bar having a mounting surface, said mounting surface extending transverse to said optical outputs of said optical demultiplexer, wherein said mounting surface comprises:
a first plurality of conductive paths extending from a first side of said mounting surface;
a second plurality of conductive paths extending from said first side o

Assignees

• Applied Optoelectronics Inc

Inventors

• Ho I-Lung
• Wang Chong
• Peng Luohan

Classifications

• H01L31/0203 Primary

  Electricity · mapped topic

• H04B10/40

  Transceivers · CPC title

• G02B6/00

  Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings · CPC title

• H10F77/50 Primary

  Encapsulations or containers (for photovoltaic modules H10F19/80) · CPC title

• G02B6/4215

  the intermediate optical elements being wavelength selective optical elements, e.g. variable wavelength optical modules or wavelength lockers (G02B6/4246 takes precedence) · CPC title