"; _cf_contextpath=""; _cf_ajaxscriptsrc="/cfthorscripts/ajax"; _cf_jsonprefix='//'; _cf_websocket_port=8578; _cf_flash_policy_port=1244; _cf_clientid='1A719EDA143D7EB39CB72503D3DC825F';/* ]]> */
PicoLuz Ultrafast Temporal Magnifier
The ultrafast temporal magnifier features new time lens technology based on the nonlinear optical process of four-wave mixing. The system is designed to stretch, or magnify, ultrafast optical waveforms in time without distorting their temporal profile. Using the magnifier, long (>100 ps) ultrafast waveforms with hundreds of sub-picosecond temporal features can be measured using GHz-bandwidth optical detectors and standard oscilloscopes.
The system can be used in two ways as depicted in the diagram below. For measuring repetitive ultrafast waveforms or high-speed digital communication signals, the magnifier will be placed between the fast signal and a sampling oscilloscope or a digital communication analyzer. Digital eye diagrams up to 1 Tb/s can be generated in this configuration. The magnifier can also be paired with real-time oscilloscopes or digitization circuits in order to generate rapidly updated snapshots of a non-repetitive ultrafast waveform (single shot sampling). For more details, please see the Technology and Single Shot Sampling Tabs.
The ultrafast temporal magnifier is sold with an external pump source (a femtosecond fiber laser) and the requried electronics to synchronize the pump repetition rate with the signal repetition rate. A list of components may be found in the Components tab. Please contact Tech Support for assistance.
Time Lens Technology
The time lens technology is based on the general concept of space-time duality, which draws a parallel between the dispersion of pulses and the diffraction of beams. The duality can be used for designing a variety of temporal imaging systems that can process optical waveforms in the time domain. The key element in such systems is a temporal analog for the spatial lens, which is called a time lens. The figure to the right shows this concept by comparing beam focusing using a lens to pulse compression using a time lens.
A time lens can be realized by imparting a temporally quadratic phase to an input signal. We use the four-wave mixing (FWM) process in nonlinear optical waveguides to realize a time lens. In addition to its ultrafast nature, this approach has several key advantages over other techniques for realizing a time lens. The FWM-based time lens can be implemented using dispersion-engineered waveguide devices, such as nonlinear fibers and silicon waveguides. Therefore, broadband processing can be achieved in any wavelength region where the waveguide material is transparent and a zero-GVD point can be reached. The guided-wave nature of this method is also crucial for applications, where fully guided systems are desired for their stability and compactness.
Four-Wave Mixing Time Lens
There are several methods for realizing a time lens. Picoluz's temporal magnifier uses the time lens technology based on four-wave mixing in nonlinear waveguides. As shown in the diagram below, a femtosecond pulse is linearly chirped and is mixed with the incoming signal via four-wave mixing wavelength conversion. The mixing process converts the wavelength of the signal, but it also transfers a quadratic phase shift to it, which creates the time lens effect. This technology enables broadband time lens-based systems built on fully guided and stable platforms.
One of the simplest forms of temporal imaging is to magnify an optical waveform in the time domain similarly to the way a lens magnifies an image. Implementing this functionality is possible by utilizing a time lens system in conjunction with appropriately designed dispersive paths. Temporal magnification generates a stretched version of an ultrafast input waveform without changing its temporal profile, which enables a low-bandwidth measurement system to directly sample the high-speed input without the need for any post-processing or retrieval algorithms [Opt. Lett. 33, 1047-1049 (2008), Opt. Express 17, 4324-4329 (2009), Opt. Express 18, 14262-14269 (2010)]. The magnification factor (M) can be changed by adjusting the output dispersion. More than one magnification factor can be provided upon request, which can then be switched by the user. Measurements below show temporal magnification with two different factors: M = 65 and M = 520.
Figure 1. Equivalent-Time (Multi-Shot) Sampling
Single Shot vs. Multi Shot Sampling
The conventional technique for sampling ultrafast optical waveforms entails using a short optical pulse and a nonlinear gating device to perform a cross-correlation measurement between the pulse and the signal under test as shown in Figure 1. This approach to signal sampling is fundamentally limited to equivalent time sampling and can only be used to detect repetitive optical waveforms or to generate binary data eye diagrams. In contrast, the temporal magnifier system generates stretched snapshots of the input waveform that are updated at the repetition rate of the pump source (typically tens of MHz).
When the magnifier is paired with a real-time sampling device, the stretched snapshots of the input waveform can be individually detected and analyzed, enabling the measurement of non-repetitive waveforms. In this case, the sampling rate of the system will be the magnification factor (M) multiplied by the real-time sampling rate of the oscilloscope as shown in Figure 2. For example, when a temporal magnification system with M = 200 is used with a 20 GS/s oscilloscope, the waveform is sampled at a 4 TS/s sampling rate.
Figure 2. Single-Shot Sampling Using Temporal Imaging
The measurement in Figure 3 shows the single-shot capability of the magnifier system by characterizing a non-repetitive optical waveform. The input waveform consists of two pulses that are separated by a fixed 2.1 ps delay, but their amplitude is modulated with a 15 MHz sinusoidal signal. The plot shows 11 consecutive snapshots of the waveform captured using a 250X temporal magnifier on a 4 GHz real-time oscilloscope. The snapshots are updated every 4 ns, which is fast enough to show the rapid amplitude modulation of the input waveform.
Figure 3. Non-Repetitive Signal Sampling
The ultrafast temporal magnifier is sold with an external pump source (a femtosecond fiber laser) and the requried electronics to synchronize the pump repetition rate with the signal repetition rate. Please contact Tech Support for assistance.
The temporal magnifier system includes synchronization electronics that allow for synchronizing the repetition rate of the pump laser to that of the signal under test. In a synchronized state, adjusting the relative delay between the input waveform and the pump pulse scans the time lens viewing window with respect to the input waveform. The temporal magnifier unit (UTM-1500) includes an integrated delay line with continuous scan range of 160 ps, which is sufficient for applications involving high-repetition-rate signals (>10 GHz). In addition, the temporal magnifier kit features an optional fiber-to-fiber long-range delay line for continuously adjustable delay up to 4 ns, which is applicable for signals with repetition rates lower than 10 GHz.
Synchronization between the pump and the input signal repetition rates is not required in applications where the signal repetition period is shorter than the magnifier record length and real-time sampling is performed. In most other applications, synchronization should be achieved between the pump and signal repetition rates.
Arbitrary Waveform Characterization
The temporal magnifier stretches the input waveform within its viewing window (record length) and allows direct sampling of the waveform without the need for post processing or retrieval algorithms. As a result, very complex ultrafast waveforms with hundreds of temporal features can be imaged and detected on standard detectors and oscilloscopes. In this experiment, we generate a 40-ps long waveform from an arbitrary waveform generator. The magnifier is configured with a 520X magnification factor allowing the waveform to be detected on a 5-GHz oscilloscope [Opt. Express 17, 4324-4329 (2009)].
Pulse Distortion Characterization
This experiment shows how the magnifier can be used to detect small distortions caused by the third-order dispersion in a zero-dispersion device (or communication link). We send a 0.8 ps pulse into the device under test with negligible GVD and TOD ˜ 0.1 ps3. The resulting pulse is asymmetrically distorted and the magnifier (with a 100X stretching factor) enables the characterization of this pulse using a 10 GHz oscilloscope.
Non-Repetitive Waveform Characterization (Single-Shot Sampling)
This experiment demonstrates the single-shot capability of the temporal magnifier system. A simple waveform consisting of two pulses that are separated by 2.1 ps is generated from a mode-locked laser operating at 250 MHz repetition rate. The amplitude of the signal is modulated using a modulator driven by a 15 MHz sine wave. The magnifier in configured with a 250X magnification factor and it uses a pump source at 250 MHz repetition rate that is synchronized with the signal repetition rate. The magnifier output is sampled on a 4 GHz (20 GigaSample/second) real-time oscilloscope and a trace showing 11 consecutive snap-shots of the input waveform is plotted below. As seen in this example, the time lens image of the input waveform is updated at the repetition rate of the pump laser used in the magnifier system (250 MHz in this example).
High-Speed Eye Diagram Measurement
The temporal resolution of the magnifier allows for data eye diagram measurements up to 1Tb/s. In this experiment, we generate an 80 Gb/s RZ data stream (data rate limited by the signal source pulse width) and we utilize a magnifier with a 65X magnification factor to measure the data eye diagram using a 10 GHz oscilloscope. The magnifier in this experiment uses a femtosecond fiber laser at 50 MHz repetition rate as the pump source. This repetition rate is synchronized with the 10 GHz RF signal that generates the data stream [Opt. Express 17, 4324-4329 (2009)].