Taking the broadband chaotic output from a weak-resonant-cavity Fabry-Perot laser diode (WRC-FPLD) under filtered feedback as a chaotic entropy source, we propose and experimentally demonstrate a scheme for generating fast physical random bits (PRBs) at a rate up to 240 Gbits/s. First, we investigate the dependence of the dynamical properties of the filtered feedback WRC-FPLD on the system parameters, and determine the optimized parameter region for generating wavelength-tunable and broadband chaotic signals. Second, a broadband chaotic signal with a bandwidth beyond 20 GHz output from the WRC-FPLD is sampled and transferred to a digital bit sequence by an 8-bit analog-to-digital converter at a rate of 40 GS/s. Finally, by utilizing multi-bit post-processing method, PRBs is generated at a rate up to 240 Gbits/s, which can pass all the 15 NIST statistics tests and meet the strict criteria of the statistical bias and the serial correlation coefficient.
Taking the broadband chaotic output from a weak-resonant-cavity Fabry-Perot laser diode (WRC-FPLD) under filtered feedback as a chaotic entropy source, we propose and experimentally demonstrate a scheme for generating fast physical random bits (PRBs) at a rate up to 240 Gbits/s. First, we investigate the dependence of the dynamical properties of the filtered feedback WRC-FPLD on the system parameters, and determine the optimized parameter region for generating wavelength-tunable and broadband chaotic signals. Second, a broadband chaotic signal with a bandwidth beyond 20 GHz output from the WRC-FPLD is sampled and transferred to a digital bit sequence by an 8-bit analog-to-digital converter at a rate of 40 GS/s. Finally, by utilizing multi-bit post-processing method, PRBs is generated at a rate up to 240 Gbits/s, which can pass all the 15 NIST statistics tests and meet the strict criteria of the statistical bias and the serial correlation coefficient.
Using two mutually coupled semiconductor lasers (MC-SLs) outputs as chaotic entropy sources, a scheme for generating Tbits/s ultra-fast physical random bit (PRB) is demonstrated and analyzed experimentally. Firstly, two entropy sources originating from two chaotic outputs of MC-SLs are obtained in parallel. Secondly, by adopting multiple optimized post-processing methods, two PRB streams with the generation rate of 0.56 Tbits/s are extracted from the two entropy sources and their randomness are verified by using NIST Special Publication 800-22 statistical tests. Through merging the two sets of 0.56 Tbits/s PRB streams by an interleaving operation, a third set of 1.12 Tbits/s PRB stream, which meets all the quality criteria of NIST statistical tests, can be further acquired. Finally, after additionally taking into account the restriction of the min-entropy, the generation rate of two sets of PRB stream from the two entropy sources can still attain 0.48 Tbits/s, and then a third set of merging PRB stream is 0.96 Tbits/s. Moreover, for the sequence length of the order of 10 Gbits, the statistical bias and serial correlation coefficient of three sets of PRB streams are also analyzed.
Chaotic light generated by optical feedback semiconductor laser is employed as entropy source. We experimentally obtain random bit sequences of different rates by using a series of processing on chaotic signals, such as photoelectric conversion, analog-digital conversion, and exclusive OR operation. Based on the principle, we develop a 2.5 Gbit/s physical random bit generator prototype which can steadily run for a long time. It can generate random bit sequence at 155 Mbit/s, 622 Mbit/s, 1.25 Gbit/s, 2.5 Gbit/s and so on, whose rates are consistent with the current communication rates. All random bit sequences with different bit rates pass all of the NIST statistical tests. The generated random bits will be used as high-speed real-time physical keys for the one-time padding secure communication.
Ultrafast physical random bit (PRB) generators and integrated schemes have proven to be valuable in a broad range of scientific and technological applications. In this study, we experimentally demonstrated a PRB scheme with a chaotic microcomb using a chip-scale integrated resonator. A microcomb contained hundreds of chaotic channels, and each comb tooth functioned as an entropy source for the PRB. First, a 12 Gbits/s PRB signal was obtained for each tooth channel with proper post-processing and passed the NIST Special Publication 800-22 statistical tests. The chaotic microcomb covered a wavelength range from 1430 to 1675 nm with a free spectral range (FSR) of 100 GHz. Consequently, the combined random bit sequence could achieve an ultra-high rate of about 4 Tbits/s (12 Gbits/s × 294 = 3.528 Tbits/s), with 294 teeth in the experimental microcomb. Additionally, denser microcombs were experimentally realized using an integrated resonator with 33.6 GHz FSR. A total of 805 chaotic comb teeth were observed and covered the wavelength range from 1430 to 1670 nm. In each tooth channel, 12 Gbits/s random sequences was generated, which passed the NIST test. Consequently, the total rate of the PRB was approximately 10 Tbits/s (12 Gbits/s × 805 = 9.66 Tbits/s). These results could offer potential chip solutions of Pbits/s PRB with the features of low cost and a high degree of parallelism.
Random numbers have great application value in the fields of secure communications, which are commonly used as secret keys to encrypt the information. To guarantee that the information is absolutely secure in the current high-speed communication, the applied random keys should possess a generation speed not less than the encrypted data rate, according to one-time pad theory found by Shannon (Shannon C E 1949 Bell.Syst.Tech.J. 28 656) Pseudo-random numbers generated by algorithm may easily reach a fast speed, but a certain periodicity makes them difficult to meet the aforementioned demand of information security. Utilizing physical stochastic phenomena can provide reliable random numbers, called physical random number generators (RNGs). However, limited by the bandwidth of the conventional physical sources such as electronic noise, frequency jitter of oscillator and quantum randomness, the traditional physical RNG has a generation speed at a level of Mb/s typically. Therefore, real-time and ultrafast physical random number generation is urgently required from the view of absolute security for high-speed communication today. With the advent of wideband photonic entropy sources, in recent years lots of schemes for high-speed random number generation are proposed. Among them, chaotic laser has received great attention due to its ultra-wide bandwidth and large random fluctuation of intensity. The real-time speed of physical RNG based on chaotic laser is now limited under 5 Gb/s, although the reported RNG claims that an ultrafast speed of Tb/s is possible in theory. The main issues that restrict the real-time speed of RNG based on chaotic laser are from two aspects. The first aspect is electrical jitter bottleneck confronted by the electrical analog-to-digital converter (ADC). Specifically, most of the methods of extracting random numbers are first to convert the chaotic laser into an electrical signal by a photo-detector, then use an electrical ADC driven by radio frequency (RF) clock to sample and quantify the chaotic signal in electronic domain. Unfortunately, the response rate of ADC is below Gb/s restricted by the aperture jitter (several picoseconds) of RF clock in the sample and hold circuit. The second aspect comes from the complex post-processes, which are fundamental in current RNG techniques to realize a good randomness. The strict synchronization among post-processing components (e.g., XOR gates, memory buffers, high-order difference) is controlled by an RF clock. Similarly, it is also an insurmountable obstacle to achieve an accurate synchronization due to the electronic jitter of the RF clock. In this paper, we propose a method of ultrafast multi-bit physical RNG based on chaotic laser without any post-process. In this method, a train of optical pulses generated by a GHz mode-locked laser with low temporal jitter at a level of fs is used as an optical sampling clock. The chaotic laser is sampled in the optical domain through a low switching energy and high-linearity terahertz optical asymmetric demultiplexer (TOAD) sampler, which is a fiber loop with an asymmetrical nonlinear semiconductor optical amplifier. Then, the peak amplitude of each sampled chaotic pulse is digitized by a multi-bit comparator (i.e., a multi-bit ADC without sample and hold circuit) and converted into random numbers directly. Specifically, a proof-of-principle experiment is executed to demonstrate the aforementioned proposed method. In this experiment, an optical feedback chaotic laser is used, which has a bandwidth of 6 GHz. Through setting a sampling rate to be 5 GSa/s and selecting 4 LSBs outputs of the 8-bit comparator, 20 Gb/s (=5 GSa/s4 LSBs) physical random number sequences are obtained. Considering the ultrafast response rate of TOAD sampler, the speed of random numbers generated by this method has the potential to reach several hundreds of Gb/s as long as the used chaotic laser has a sufficient bandwidth.
We experimentally demonstrate Tb/s fast random bit generation from random signals generated in a broadband random optoelectronic oscillator. The broadband random optoelectronic oscillator is used as photoelectron entropy source to generate wideband random signal. We sample the random waveform with a resolution of 10 bits and a sampling rate of 128 GS/s. All 10 bits can be preserved and a generation rate of 2.5 Tb/s (128 GS/s$\times 10bits\times $2 data) is achieved by using time-shift bit-order-reverse bitwise exclusive-or operation as a more complicated post-processing method. The randomness of random bit sequences is verified by using NIST Special Publication 800–22 statistical tests.
The exponential growth of data transmission and processing speeds in modern digital infrastructure requires entropy sources capable of producing large volumes of true randomness for information security. Chaotic emissions from semiconductor lasers are attractive in this context because of their fast dynamics and nonrepetitive behavior. Their spectral bandwidth, however, is typically limited to several tens of gigahertz, which constrains the achievable entropy rate and makes ultrafast random bit generation difficult without substantial post-processing. Here, we demonstrate a chaos-based entropy source that employs optical heterodyning between the chaotic emission from a semiconductor laser and an optical frequency comb, yielding a bandwidth exceeding 100 GHz and an experimentally verified single-channel entropy rate of 1.86 Tb/s. By directly extracting multiple bits from the digitized output of the entropy source, we achieve a single-channel random bit generation rate of 1.536 Tb/s, while four-channel parallelization reaches 6.144 Tb/s with no observable interchannel correlation. This linear scalability suggests that aggregate throughput could reach hundreds of terabits per second with additional parallel channels. The broadband, low-overhead photonic architecture presented here provides a viable route to real-time, ultrafast random bit generation with broad implications for secure communications, high-performance AI computing, and large-scale data analytics.