Dr. Vadym Zayets

The spin photon memory has operational speed near 1 TBit/sec, which is about 1000 times faster the speed of any presently-available memory. Also, the recording of spin-photon memory is non-volatile. These two unique properties make spin-photon memory very desirable for variety of applications. However, a buffer memory and chip-to-chip connection are two major applications of the spin-photon memory.

Buffer memory

Even high-speed optical fiber links are widely installed worldwide, only a little of their high-speed capacity are used. At present, the transfer rate of 25.4 TBit/sec through single optical fiber was demonstrated. However, the actual speed of the present networks is significantly slower. The speed of a network is mostly limited by the speed of the network routers. The network router switches data streams between different nods in a network. The function of the network router is to receive the data package from one channel, to store it, and send it to the second channel.  Since the availability of second cannel is basically unknown, the router should memorize the data until the second channel will be available. The high-speed memory is a major element for a network router. The routers made of electrical components are installed in the present optical networks. Because of the speed limitation of electrical memory, the speed of the commercial routers is limited to about 40 GBit/sec, which is significantly below the capacity of the present optical fiber links. Unavailability of high-speed optical memory is major obstacle limiting the speed of the servers. In order to increase the network speed, the developing of new designs of the high-speed optical memory is essential. 

 

Chip-to chip inter connection

Another important application of the spin photon memory is chip-to chip inter connection. The purpose of the connection is to transfer a data from one silicon chip to another in shortest possible time. In a silicon chip the electrical memory, like DRAM, SRAM or MRAM, is dense, but has a moderate operational speed. For the data transfer inside the chip the moderate speed is not a problem, because inside it is easy to make many connection lines and transfer the data from memory to memory in parallel. Therefore, a large amount of data can be transferred inside the chip in short time. However, in the case of chip-to-chip interconnection, it is impossible to make a huge amount of the connections lines and usage of a high-speed buffer memory is required. The buffer memory does not need to be dense, but it must be very fast.

Figure 2 shows an example of chip-to-chip interconnection, where two chips are connected by an optical fiber. The blue region represents electrical memory and the yellow region represents a high-speed optical buffer memory. In order to transfer a large amount of data from electrical memory of one chip to the electrical memory of another chip, at first the data transferred from the electrical memory to the buffer memory in parallel, next from the buffer memory of one chip to the buffer memory of another chip through the fiber in serial at high speed and next the data from the buffer memory is transferred to electrical memory in parallel. Therefore, over all the high speed of data transfer can be achieved.

 

The same content can be found in Zayets, Electronics (2017) and Zayets, APL 94 (2009)( pdf is here)