BACKGROUND OF THE INVENTION

The present disclosure is related to an optical transmitting device. More particularly, the present invention provides an improved 1550 nm DFB laser diode package on a submount sharing the cold side of a built-in thermoelectric cooling module with an assembly of an aspherical optical coupling lens. Processes for assembling the optical transmitting device are also disclosed.

As science and technology are updated rapidly, processing speed and capacity of the computer increase correspondingly. The communication transmission or reception using the traditional cable is limited to bandwidth and transmission speed of the traditional cable and mass information transmission required in modern life causes the traditional communication transmission overload. To correspond to such requirement, the optical fiber transmission system replaces the traditional communication transmission system gradually. The optical fiber transmission system does not have similar bandwidth limitations, and also has advantages of higher speed transmission, longer transmission distance, its material is not susceptible to the electromagnetic interference. Therefore, present electronic industry performs research in optical fiber transmission which will become the mainstream in the future. Said optical communication is a technology in that light functions as signal carrier and is transmitted between two nodes via the optical fiber. Field of the optical communication can be divided into optical communication side and electrical communication side according to the transmission medium. By the optical transceiver, the received optical signal can be converted to an electrical signal capable of being processed by an IC, or the processed electrical signal can be converted to the optical signal to be transmitted via optical fiber. Therefore, objective of communication can be achieved.

Wavelength-division multiplexing (WDM) is a multitask technology of processing multiple optical carrier signals transmitted by the optical fiber, and this technology is applied on the different wavelengths of laser optical signal. Besides, the term “wavelength-division multiplexing” is mostly applied in optical carrier, and frequency-division multiplexing is applied in radio carrier. Moreover, both of wavelength and frequency are in reciprocal relationship, so their concept can be applied to each other.

Wavelength-division multiplexing is implemented by dividing the data channel into multiple wavelengths in the optical fiber to enable mass data transmission in one optical fiber. The complete dense-wavelength-division multiplexing (DWDM) system can be implemented by a wavelength division multiplexer at transmitting end and a wavelength division demultiplexer at receiving end. At present, there are commercial wavelength division multiplexer/demultiplexer which can combine/divide 80 or more channels in the optical fiber communication system, so that the data transmission speed can exceed multiple Tb/s effectively.

In the transmitting module adapted for DWDM technology, the connector usually has single light transmitter structure. However, such light transmitter structure can emit optical signal with preset frequency which usually lacks stability and often drifts away from the preset wavelength during environmental temperature changes. Although adding thermoelectric cooler module to the transmitting device is known, an improved package integrating a thermister, a thermoelectric cooler (TEC) module, and a laser diode (LD) chip on a submount sharing a common code side of the TEC module with an aspherical optical coupling lens is still highly desired for enhancing control of operation temperature, wavelength tunability and stability, and LD-to-fiber coupling efficiency of emitted light especially in 1550 nm DWDM channels.

BRIEF SUMMARY OF THE INVENTION

The present disclosure is related to an optical transmitting device. More particularly, the present invention provides an improved package integrating C-band DFB laser diode, thermoelectric cooler (TEC) module, directly to a submount attached to a cold-side of the TEC module together with an assembly of an aspherical optical coupling lens. Processes for assembling the optical transmitting device are also disclosed. In certain embodiments, the invention is applied to multiple optical transmitting devices configured to be assembled in upside-down fashion with a top housing disposed at bottom on PCB of a transceiver with QSFP Small Form Factor (SFF) specification for high bandwidth optical communication including wideband tunable application, though other applications are possible.

In a specific embodiment, the present invention provides a packaged transmitter device. The packaged transmitter device includes a base member comprising a planar part mounted with a thermoelectric cooler module, a transmitter module, and an optical coupling lens assembly, and an assembling part connected to one side of the planar part. The packaged transmitter device further includes a circuit board bended to have a first end region being disposed on a top surface of the planar part and a second end region being raised to a higher level. The first end region includes multiple electrical connection patches respectively connected to the thermoelectric module and the transmitter module. The second end region includes an electrical port for external connection. Additionally, the packaged transmitter device includes a cover member disposed to a fixed position over the planar part to at least cover the thermoelectric module, the transmitter module, the optical coupling lens assembly, and the first end region of the circuit board. Furthermore, the packaged transmitter device includes a cylindrical member installed to the assembling part for enclosing an isolator aligned to the optical coupling lens assembly along its axial line and connected to an optical fiber to couple optical signal from the transmitter module to the optical fiber.

Therefore, the present disclosure has at least following advantages. First, the optical transmitter package structure provide a compact transmit module that integrates a thermistor chip, a monitor photodiode (MPD) chip, and laser diode (LD) chip on a submount attached to a cold side surface of a thermoelectric cooler module for improving wavelength stability. Secondly, the package structure further disposes an optical coupling lens assembly next to the submount on the same cold side surface of a thermoelectric cooler module so that the distance between the LD chip and the coupling lens can be fixed without being affected by environmental temperature change. The coupling lens is an aspherical lens providing optimal optical coupling of the emitted laser light from the LD chip at a small first distance and better efficiency to focus into an optical core of fiber at a larger second distance. This simplifies calibration process in X-Y plane and Z-axis for optical alignment of the transmitter device with improved coupling efficiency. The transmitter module on the submount and the coupling lens assembly still can be easily detached so that the lens body can be recycled for reuse when the transmitter module is damaged. Thirdly, the transmitter package structure disposes the TEC module in a recessed region of a base member that is conveniently set to form a thermal contact with a lid member as a good heat sink. Fourthly, a bended circuit board associated with the transmitter device allows the transmitter device to be installed in an upside-down fashion when one or more such transmitter devices are assembled in a QSFP SFF package of a photonic transceiver device to facilitate device heat dissipation by utilizing the lid member as a good heat sink.

The present invention achieves these benefits and others in the context of known optical package technology. However, a further understanding of the nature and advantages of the present invention may be realized by reference to the latter portions of the specification and attached drawings.

