Optical Transmitter
There is provided a novel configuration and mounting form of an optical transmitter that suppresses temperature dependency of optical modulation output characteristics and has excellent speed. An optical transmitter according to the present disclosure includes an optical modulator chip, a driver IC for operating the optical modulator chip, a wiring layer that guides a modulated electrical signal supplied from an external digital signal processor (DSP) to the driver IC, a gold wire line that connects each of the driver IC and the optical modulator chip, and the wiring layer and the driver IC via a PAD, and a Peltier device mounted below the optical modulator chip and the driver IC, in which the optical modulator chip and the driver IC are temperature-controlled by the Peltier device that is the same.
1 . An optical transmitter comprising:
an optical modulator chip;
a driver IC for operating the optical modulator chip;
a wiring layer that guides a modulated electrical signal supplied from an external digital signal processor (DSP) to the driver IC;
a gold wire line that connects each of the driver IC and the optical modulator chip, and the wiring layer and the driver IC via a PAD; and
a Peltier device mounted below the optical modulator chip and the driver IC, wherein
the optical modulator chip and the driver IC are temperature-controlled by the Peltier device that is the same.
2 . The optical transmitter according to claim 1 , wherein
the gold wire line is a ball wire having a loop,
a height difference between an upper surface of the optical modulator and an upper surface of the driver IC is equal to or less than 100 μm,
a height difference between an upper surface of the wiring layer and an upper surface of the driver IC is equal to or less than 100 μm, and
in the driver IC and the PAD installed in the optical modulator chip, at least two or more of the gold wire lines are connected between signal PADs that signals are propagated.
3 . The optical transmitter according to claim 1 , wherein
the gold wire line is a ribbon wire having a planar shape, and
heights of an upper surface of the optical modulator, an upper surface of the driver IC, and an upper surface of the wiring layer coincide with each other.
4 . The optical transmitter according to claim 2 , wherein a distance between the optical modulator and the driver IC is 50 μm or less, and the PAD that the gold wire line is connected is formed at a position within 50 μm from a chip end surface of the optical modulator or the driver IC.
5 . The optical transmitter according to claim 1 , wherein the temperature of the Peltier device is controlled to be constant at any temperature in a range of 25 to 50° C.
6 . The optical transmitter according to claim 1 , wherein
a material of an upper surface of the Peltier device is aluminum nitride (AlN),
the optical modulator chip is an indium phosphide (InP) optical modulator chip, and
the Peltier device is connected to the optical modulator chip and the driver IC by a conductive paste or solder having a thermal conductivity of 30 W/m K or more.
7 . The optical transmitter according to claim 1 , further comprising:
an optical member that temperature is controlled by the Peltier device, wherein
element densities of n-type and p-type semiconductors constituting the Peltier device are set such that an area that the driver IC is mounted, an area that the optical modulator chip is mounted, a mounting area of the optical member are in descent order.
8 . The optical transmitter according to claim 1 , further comprising a subcarrier between the Peltier device and the optical modulator chip and the driver IC.
9 . The optical transmitter according to claim 7 , further comprising a thermal separation groove on at least one of an upper surface or a lower surface of the subcarrier between the driver IC and the optical modulator chip.
10 . The optical transmitter according to claim 1 , wherein
the optical modulator chip and the driver IC are mounted in a housing in a HB-CDM form, and
the optical modulator chip and the driver IC have a differential line configuration.