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PDM-IR user manual v

3.0.3

 

 

 

 

 

Micro Photon Devices S.r.l. – Italy  All Rights Reserved 

 

8

 

 

not blanked during the hold-off time (VALID GATE is a digital signal with the same pattern of Gate). This 
information  is  particularly  useful  when  looking  for  the  percentage  of  counts  over  the  total  number  of 
available valid gates. In fact, in timing measurements one must be careful not to exceed the single-photon 
statistics, in order not to distort the TCSPC histogram (see paragraph 6.1.2). 

2.2

 

Free Running Operation 

As already discussed, normally single photon detectors are operated in the so-called free-running mode, 
where the devices are enabled immediately after the quenching of each avalanche current. PDM-IR allows 
the user the possibility to choose which type of module operation, and thus not only the gated mode but 
also the free running mode is possible with PDM-IR. In this mode of operation, as shown in Figure 4, TRIGGER 
GATE signal is no more useful because the SPAD is always enabled until an avalanche is triggered. After each 
of them, the SPAD is disabled for the hold off time and then immediately and swiftly re-enabled. 

Overall, as a suggestion, the gated mode is used to achieve the best Signal-to-Noise (SNR) ratios and timing 
resolutions whenever the signal to be detected is synchronous with a reference signal (for example the laser 
clock used to stimulate the signal emission) that can be used to synchronize the PDM-IR. Indeed, better S/N 
ratio or dynamic range, in case of TCSPC measurements, are achieved by enabling the detector only for the 
short windows where the signal is present and keeping the detector off whenever the signal is not present. 

The free running mode is typically used instead whenever the signal to be detected is not synchronous with 
a reference signal (like the stimulated emission of photons from a nonlinear crystal by a CW laser). Of course, 
free-running mode can also be used whenever a synchronous signal has to be detected but the S/N ratio (or 
the dynamic range) is, in this case, lower compared to the gated mode module since the detector is always 
enabled and InGaAs/InP diodes have much higher noise and after pulsing, compared to the silicon diodes. 

 

Figure 4.  Main waveforms for PDM-IR module in case of the free running operation: TRIGGER GATE is not significative 

and ignored, the SPAD detector enabling time (GATE), the off time in case of avalanche (HOLD OFF) and 

photon output signal (PHOTON OUTPUT). 

Содержание PDM-IR

Страница 1: ...R 900 nm 1700 nm Infrared Photon Detection Module ã Micro Photon Devices S r l Via Stradivari 4 39100 Bolzano BZ Italy email info micro photon devices com Phone 39 0471 051212 Fax 39 0471 501524 PDM IR User Manual Version 3 0 3 September 2018 ...

Страница 2: ...PDM IR Trigger Section 14 4 1 1 Internal Trigger 15 4 1 2 Trigger In 16 4 1 3 Aux In 16 4 1 4 Logic Function 17 4 2 PDM IR Gate Section 18 4 2 1 Gated mode with fixed gate width operation 19 4 2 2 Gated mode with Free gate operation 20 4 2 3 Free running mode 20 4 3 PDM IR SPAD Section 21 4 3 1 Temperature 22 4 3 2 Excess Bias 22 4 3 3 Hold Off 22 4 4 PDM IR Counters Section 23 4 5 PDM IR Output S...

Страница 3: ...dow Counter Section 33 5 2 6 Counter Window 34 5 2 7 Module Selection Window 34 5 2 8 Module Info Window 35 5 2 9 Configurations Window 35 5 2 10 Save configuration Window 36 5 2 11 RunTime Menu 37 6 SETUPS 38 6 1 Basic setups 38 6 1 1 Photon Counting setup 38 6 1 2 Photon Timing setup 40 6 2 Advanced setups 41 6 2 1 Cross correlation setup with external sync 41 6 2 2 Cross correlation setup witho...

Страница 4: ...ve bias voltage resetting and some sub circuits for signal conditioning All the main parameters and delay paths are adjustable by the user through the software interface in order to match the requirements of different applications The system can be conveniently used both for counting and timing measurements since the high performance electronics guarantees a clean temporal response even with fast ...

Страница 5: ...al noise consists in a random dark counting rate DCR arising from free carriers thermally generated These events compete with photons in triggering the detector and thus impair the signal to noise ratio The Peltier cooler is therefore useful to lower the temperature of the detector in order to diminish this effect 2 1 Gated Mode Operation Normally single photon detectors are operated in the so cal...

Страница 6: ...ce the afterpulsing effect worsens at low temperatures because the decay times of the trapped carriers increase The hold off time is usually longer than the gate period T An example of a photon counter module operated in gated mode and employing the hold off feature is shown in Figure 3 The reference signal is TRIGGER GATE which sets the gate repetition rate frequency The signal actually applied t...

Страница 7: ...MPD PDM IR biases the SPAD in gated mode and applies the hold off every time an avalanche is detected the two effects must be applied at the same time in order to obtain the correct photon counting rate CRphoton from the measured counting rate CR From simple mathematics it turns out that the final equation is the following 𝐶𝑅IJKLKM 1 𝑇 log N1 𝐶𝑅 1 𝐶𝑅 𝑇F 𝑇O which can then be simplified to 𝐶𝑅IJKLKM ...

Страница 8: ...nabled Overall as a suggestion the gated mode is used to achieve the best Signal to Noise SNR ratios and timing resolutions whenever the signal to be detected is synchronous with a reference signal for example the laser clock used to stimulate the signal emission that can be used to synchronize the PDM IR Indeed better S N ratio or dynamic range in case of TCSPC measurements are achieved by enabli...

Страница 9: ...rgio Cova Single photon avalanche diodes for the near infrared range detector and circuit issues Journal of Modern Optics 56 2 3 299 308 2008 http dx doi org 10 1080 09500340802263075 Alberto Tosi Alberto Dalla Mora Simone Tisa Fabio Acerbi Franco Zappa and Sergio Cova InGaAs InP SPADs for near infrared applications device operating conditions and dedicated electronics Proc SPIE 7681 Advanced Phot...

Страница 10: ...his signal TTL AUX OUT RF output requires 50 Ohm DC terminated transmission lines Electric pulses of 3 3V LVTTL are generated at this output Output signal is user selectable See paragraph 4 5 for the available possibilities and for a complete electrical description of this signal AUX IN RF input 50 Ohm with fixed DC impedance The trigger signal can be positive or negative and the input internal th...

Страница 11: ...PDM IR user manual v3 0 3 Micro Photon Devices S r l Italy All Rights Reserved 11 3 2 PDM IR Mechanical Dimension Figure 6 Mechanical dimensions of the PDM IR fiber pigtailed version ...

Страница 12: ...PDM IR user manual v3 0 3 Micro Photon Devices S r l Italy All Rights Reserved 12 Figure 7 Mechanical dimensions of the PDM IR free space version ...

Страница 13: ...re 10 Finally GATE signal can be generated either by exactly replicating TRIGGER GATE Figure 13 or by creating a new signal synchronized with the rising edge of TRIGGER GATE and with a fixed gated ON width equal to the user set TON value Figure 12 See paragraph 4 2 for more details Of course as discussed in paragraph 2 independently of the chosen trigger pattern GATE signal is disabled for the dur...

Страница 14: ...ph 4 4 Finally in the PDM IR all the main signal paths have a programmable delay designed to help the user in synchronizing the various signals between them and with the external instruments This feature is very helpful in many applications as it allows to avoid the hassle of continuously changing the cable length In Figure 8 the full PDM IR block diagram is shown while in the next paragraphs we w...

Страница 15: ... each sub block of the Trigger section shown in Figure 9 is illustrated 4 1 1 Internal Trigger The INTERNAL TRIGGER is an internally created waveform with a periodic pattern with fixed frequency selectable by the user and a duty cycle equal to 50 In order to be able to synchronize the PDM IR module with other instrumentations set the TTL AUX OUT and or the NIM AUX OUT to output the INTERNAL TRIGGE...

Страница 16: ...ve VOV_IN 100 mV Trigger In pulse width tIN_PULSEmin 800 ps Trigger In Slew Rate SRIN 10 V µs Trigger In Edge Neg pos Trigger In Threshold VTH_IN 2 2 V Trigger In Threshold resolution ΔVTH_IN 10 mV 4 1 3 Aux In The AUX IN input is provided by the user can be periodic or aperiodic positive and or negative It s an auxiliary signal useful to enable or disable the SPAD in certain conditions Threshold ...

Страница 17: ...w Rate SRAUX 10 V µs Aux In Edge Neg pos Aux In Threshold VTH_AUX 2 2 V Aux in Threshold resolution ΔVTH_AUX 10 mV Figure 10 Advance trigger section using AUX IN signal in logic function with TRIGGER IN signal TRIGGERGATE is shown in case of use the OR port and the AND port between the two signals 4 1 4 Logic Function The Logic Function Block allows advanced gate triggering using TRIGGER selected ...

Страница 18: ...g mode and thus becomes TRIGGER GATE independent see 4 2 3 The EFFECTIVE GATE whose electrical characteristics are shown in Table 5 can also be delayed before being applied to the SPAD The GATE signal is thus the EFFECTIVE GATE after a user controllable delay and with the HOLD OFF also user controllable applied after every avalanche triggering As GATE depends on the actual photon flux it can only ...

Страница 19: ... be set asynchronous HOLD OFF LEVEL With the HOLD OFF EDGE modality the first gate window to be applied to the SPAD following the end of a HOLD OFF is the first one to have its rising edge positioned in time after the end of the hold off as shown in Figure 12 In this case as shown in Figure 12 the gate window that happens across the time instant that the HOLD OFF ends is skipped The use of HOLD OF...

Страница 20: ...of TRIGGER GATE apart of course when the HOLD OFF is applied In fact in this mode of operation TRIGGER GATE and EFFECTIVE GATE are identical Even in gate mode with Free gate operation in case of photon detection all GATE windows that occur during a HOLD OFF are masked Finally even with this mode of operation HOLD OFF LEVEL and HOLD OFF EDGE can be chosen In Free gate operation opposite to the gate...

Страница 21: ...rature the lower the DCR but the higher the afterpulsing effect given a hold off time as the trap decay times increase Of course when setting the lowest SPAD temperatures the PDM IR must be placed on a good heatsink so that it can dissipate the heath generated by the Peltier cooler If this is not done the module might heat up too much and go in safe mode shutting down the detector operation In Fig...

Страница 22: ... about 20 22 C will be required 4 3 2 Excess Bias The excess bias is the difference between the SPAD bias voltage and its breakdown and it controls directly the SPAD performance the higher the Excess Bias the higher the Photon Detection Efficiency PDE the better the timing resolution but the higher the DCR As the DCR increases more than linearly while the PDE increases linearly or less than linear...

Страница 23: ...lly at short integration time the count data are stored in a 20 positions circular array that are automatically read from the VisualPDM IR software or that can be read by using the provided SDK The counter characteristics are shown in Table 7 4 5 PDM IR Output Section The PDM IR provides the PHOTON OUT output and two user selectable outputs a positive LVTTL output and a negative NIM output Both ou...

Страница 24: ...d 0 V Photon Out high logic level VOL_NIM 50 Ω termination required 800 mV Photon Out Rise Fall Time 20 80 400 ps Photon Out Pulse width 10 ns 4 5 1 PHOTON OUT The PHOTON OUT generates an output pulse according to the NIM standard with low timing jitter In this way it precisely marks the photon arrival time It has a fixed delay between the photon arrival time and a specific output connector see pa...

Страница 25: ...ble 9 LED color meaning OFF LED when the LED is OFF there are 2 possibilities the module is not powered ON or the module is correctly working and the SPAD is enabled BLINKING ORANGE a blinking orange LED indicates that the PDM IR is powered ON but the SPAD is not polarized This state is active for less than 10 seconds after powering ON the module or whenever the SPAD has been turned off using the ...

Страница 26: ...urate within 5 ns and they have been measured with all the programmable delays set to 0 ns Procedure Action Initial condition LED sequence Final Condition Switching on the PDM IR PDM IR not powered OFF BLINKING ORANGE for 10 seconds ORANGE until SPAD ON GREEN for 5 seconds OFF SPAD ON Updating a parameter SPAD ON OFF ORANGE GREEN ORANGE until parameters updated GREEN for 5 seconds OFF SPAD ON para...

Страница 27: ... AUX OUT as TRIGGER GATE 26 ns TRIGGER AUX GATE 30 ns TTL AUX OUT as TRIGGER GATE 28 ns NIM AUX OUT as TRIGGER GATE 26 ns GATE TTL AUX OUT as VALID GATE 12 ns NIM AUX OUT as VALID GATE 14 ns TTL AUX OUT as INTERNAL TRIGGER GATE 14 ns NIM AUX OUT as INTERNAL TRIGGER GATE 12 ns HOLD OFF TTL AUX OUT as HOLD OFF 18 ns NIM AUX OUT as HOLD OFF 16 ns PHOTON PHOTON OUT 5 ns TTL AUX OUT as PHOTON OUT 22 ns...

Страница 28: ...driver from FTDI included in the PDM IR USB Key must be installed before connecting the PDM IR to the PC 5 2 Software Interface The VisualPDM IR interface is composed by a main window divided in several sections as shown in Figure 18 and a satellite window for each active counter see Figure 24 Figure 18 Screenshot of the main window of the graphical user interface 5 2 1 Main Window Trigger and Gat...

Страница 29: ...ge Edge Selection List the threshold level VTH_AUX and the delay of AUX IN δTRIGGER_AUX These controls are disabled when Logic Function gate List is equal to Only see below Trigger Selection List let the user to choose TRIGGER between INTERNAL TRIGGER and TRIGGER IN Edge Selection List selection list used in both the Aux In settings box and the Trigger In settings box for choosing the rising or th...

Страница 30: ...th Settings these fields allows to select the gate mode see PDM IR Gate Section the TON width and the delay of the EFFECTIVE GATE δ EFFECTIVE_GATE The TON field is of course visible only in case of gate mode with fixed gated width Gate Mode List allows to choose the Gate Mode operation It can be gate mode with fixed gate width Fixed Gate gate mode with free gate operation Free Gate or Free running...

Страница 31: ... for details 5 2 3 Main Window Output Section The panel in Figure 21 manages the outputs see paragraph 4 5 Each control is explained in Table 14 Figure 21 Output Section of the VisualPDM IR Main Windows Table 14 Output Section controls explained TTL AUX OUT these two fields set the desired TTL output signal chosen from the Out Signal List and the delay introduced in the output path δTTL_AUX NIM AU...

Страница 32: ...bias voltage is currently changing Light Green LED means that the SPAD is correctly biased and ready to detect photons according to the GATE settings Red LED indicates that an error occurred during the SPAD bias voltage setting Gate Status Indicates the gate mode status Dark Green LED denotes that the Gate is off Yellow LED denotes that PDM IR is updating GATE settings Light Green LED means that t...

Страница 33: ...able 16 Counter Section controls explained Counter Values displays the last values read from each counter OFF button it s visible when the counter is enabled The OFF button disables the counter Graph button opens the time chart of the relative counter see 5 2 6 ON button it s visible when the counter is disabled The ON button enables the counter and the Graph button Graph button it is disabled and...

Страница 34: ...Rs connected at the same PC the software offers the possibility to control all of them by means of the pop up widow shown in Figure 25 In this figure the list of all detected PDM IR modules is indicated allowing the user to choose or change the controlled PDM IR by the Serial Number Actual active module is also shown by the SW interface in the top left corner as shown in Figure 18 The pop up windo...

Страница 35: ... is called a Configuration With the VisualPDM IR it is possible to save multiple configurations and load them whenever a specific one is needed for a particular application or experimental set up In order to see which configurations are stored and to load them the Load Configuration menu item in the Configurations run time menu should be pressed Upon pressing the pop up window shown in Figure 27 i...

Страница 36: ...d thus can be accessed anywhere even when a module is moved from one lab to another and thus connected to different PCs 5 2 10Save configuration Window In order to save a configuration the menu item Configurations Save Configuration should be selected This action will open the window shown in Figure 28 In order to save a configuration first the desired configuration name must be written in the ded...

Страница 37: ...M IR that is controlled by the SW when more than one module are attached to the same PC By pressing the menu item the module selection window shown in paragraph 0 will appear File Exit Closes the software and the communication with the module Configurations Load Configuration Opens the configurations window see paragraph 5 2 9 Configurations Save Configuration Allows to save the current configurat...

Страница 38: ...DM IR can be used either in free running mode or in gated mode The internal counter associated to the NIM OUT Photons can also be conveniently used without the use of an external one In free running mode the measurement is straightforward see paragraph 2 for a description the various modes of operation and paragraph 4 2 3 specifically for free running as the SPAD is immediately turned on following...

Страница 39: ...PAD is enabled only during gate ON windows of width TON and period TP the calculation of the impinging photon flux CRimp is a bit more complex and equal to 𝐶𝑅RSI 1 𝑃𝐷𝐸 𝐶𝑅PKQML 1 𝐶𝑅PKQML 𝑇F 𝑇𝑃 𝑇 𝑓𝑜𝑟 𝐶𝑅PKQML 𝑇𝑃 1 𝐶𝑅PKQML 𝑇F 1 From the above equation it turns also out that 𝐶𝑅PKQML 𝑃𝐷𝐸 𝑇 𝑇𝑃 𝐶𝑅RSI 1 𝑃𝐷𝐸 𝑇 𝑇𝑃 𝐶𝑅RSI 𝑇F Which means that detecting asynchronous photons with a gated mode configuration always...

Страница 40: ...as been connected to the trigger in input of the laser In this way the laser is triggered by the PDM IR module The trigger out signal of the laser is then used as START of a TCSPC system The STOP signal to the TCSPC system is given by the PHOTON OUT of the PDM IR module It is worth noting that in this example the INTERNAL TRIGGER used to synchronize the laser has been routed to the NIM AUX OUT as ...

Страница 41: ...gate mode does not apply because for the laser pulses the SPAD behaves as if operated in free running Only the correction for the hold off time must be implemented In addition we will consider negligible the effect of the DCR and of the afterpulsing the minor error that is committed is conservative in calculating the correct counting rate for avoiding the pile up effect The condition to be satisfi...

Страница 42: ... gate width mode see 4 2 1 and with the GATE generated by TRIGGER IN 2 Connect the LASER TRIGGER OUT to the TRIGGER IN of each PDM IR by means of a wideband 50 50 power splitter the voltage levels at the outputs are the half of the input levels set the correct edge and threshold settings of the TRIGGER IN input 3 Set the correct TRIGGER IN delay so that detectors are enabled when the photons arriv...

Страница 43: ... much asynchronous photons as possible The other PDM IR is set to work in gated mode with fixed gate width and his own TRIGGER IN is connected to the NIM AUX OUT of the other module Setting the NIM AUX OUT of the free running module as PHOTON OUT the gated SPAD is enabled ONLY every time the first module detects a photon Finally in order to make this setup working two other settings must be ensure...

Страница 44: ... becomes 5kc s 1kc s or smaller and modules dark counting rates could be already in the same order of magnitude or larger It would thus seem that in case of a module with DCR 5kc s and an experiment with 100kHz of fLASER a TCSPC measurement would not be possible This is not the case Let s start from the known formula and let s also separate the contributions of the signal 𝐶𝑅dRfMcb from the noise 𝐶...

Страница 45: ...r calculating the pile up effect A better solution but a bit more difficult to implement would be to acquire only few slices of the decay curve as sampling points see Figure 34 and recreate the full decay curve fitting these points This could be achieved by using the PDM IR in gated mode with a hold off time longer than the ROI so that only one pulse per decay as in the equivalent free running mod...

Страница 46: ...uency is application dependent 2 Set the NIM AUX OUT as TRIGGER GATE and connect it to the MPD Picosecond Delayer input The PSD in this application is used as divider in order trigger the laser at the desired frequency i e 10 to 100 times less than the module gate frequency 3 Acquire the raw data of the histogram by setting correctly the TCSPC system parameters 4 Elaborate the histogram with a cus...

Страница 47: ...ions should work but were not tested Mac OS X 10 7 5 and above Copyright and disclaimer No part of this manual including the products and software described in it may be reproduced transmitted transcribed stored in a retrieval system or translated into any language in any form or by any means except for the documentation kept by the purchaser for backup purposes without the express written permiss...

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