Newport femtoFBG, Technical And Software Manual

Page 1: ...Newport femtoFBG femtoFBG Technical and Software Manual Revision 2 29 August 2019 ...

Page 2: ...anties do not apply to products which have been repaired or modified without Newport s written approval or products subjected to unusual physical thermal or electrical stress improper installation misuse abuse accident or negligence in use storage transportation or handling This warranty also does not apply to fuses batteries or damage from battery leakage THIS WARRANTY IS IN LIEU OF ALLOTHER WARR...

Page 3: ...ure that all its personnel protect the Newport Programs as trade secrets of Newport Corporation Customer shall not at any time disclose Newport s trade secrets to any other person firm organization or employee that does not need consistent with Customer s right of use hereunder to obtain access to the Newport Programs and Related Materials These restrictions shall not apply to information 1 genera...

Page 4: ...p www newport com Please provide the customer care representative with the following information Your contact information Model number and Serial number Detailed description of the problem If the instrument is to be returned you will be given an RMA number which you should reference in your shipping documents You can also contact the Newport Service Department for additional information or assista...

Page 5: ...hose specialists qualified or authorized by Newport to install and commission your femtoFBG We are not able to guarantee the proper operation unless the femtoFBG is installed by a member of the technical staff of Newport or an authorized representative of Newport This manual is intended also as a guide to the source of possible problems as well as a guide for in house maintenance or repair of your...

Page 6: ...r cables so they are not likely to be damaged Disconnect power before cleaning the equipment Do not use liquid or aerosol cleaners use only a damp lint free cloth for electronics Lockout all electrical power sources before servicing the equipment To avoid fire hazard use only the specified fuse s with the correct type number voltage and current ratings as referenced in the appropriate locations in...

Page 7: ...oper function Eye safety is of the greatest concern and the direct eye contact with a laser beam can cause serious damage and possible blindness Therefore general laser safety rules should always be observed when working with lasers and laser related instrumentation Wear appropriate protective eyewear at all times The eyewear selection depends on the wavelength and the intensity of the radiation t...

Page 8: ...he femtoFBG side cover when optical alignment is required Along with maximizing the laser safety having the side cover in place will help to minimize dust deposition on the optical elements used in the femtoFBG thus limiting cleaning or replacement of dirty or damaged optics Every effort has been made to ensure that the information in this manual is accurate All information in this document is sub...

Page 9: ...dized and chirped FBGs are easily produced using the design tools in the femtoFBG software 2 2 femtoFBG Specifications Laser wavelengths compatibility Dual 1040 nm 520 nm or 800 nm Beam entrance height 5 in 126 mm Laser power variable attenuation OD0 to OD2 Total travel distance XYZ 100 mm x 100 mm x 0 5 mm Optional upgrade option Z 4 8 mm Resolution and maximum speed XY 0 05 µm and 300 mm s Resol...

Page 10: ...ed transformer Before attempting to power up any electronic instrument for the first time the following precautions must be followed Have a qualified electrician verify the wall socket that will be used is properly polarized and properly grounded Set the mains selector tumbler to the voltage that matches the power outlet AC voltage Verify the correct rated fuses are installed according to the labe...

Page 11: ...ern 1 5 6 and 7 Figure 2 is used to locked the femtoFBG to metric tables We recommend using at least two mirrors to steer the laser beam into the femtoFBG A typical configuration is schematically shown in Figure 2 Two mirrors set at 90 are used to route the laser beam into the input of the femtoFBG The beam entrance height of the femtoFBG is fixed at 5 in 127 mm This height matches the beam output...

Page 12: ...ed on the vertical left panel as indicated in Figure 3 a Removing this panel reveals a series of optical elements Figure 3b used to condition the laser beam before entering the focusing writing assembly Figure 3 Vertical side panel of the femtoFBG with laser entrance port a Access to a series of optical elements used for beam conditioning is gained by removing the vertical side panel b A schematic...

Page 13: ...tion of the laser beam is rendered circular with quarter wave plate A beam sampler is used to direct a small portion of the laser beam to a power meter detector so to have the capability to monitor the laser average power M4 M5 and M6 are turning mirrors used to direct the laser beam trough the exit port located in the upper right of the vertical assembly Two positive lenses are employed to expand...

Page 14: ...zostage TS translational stage The first optical element the laser beam encounters at this stage is the dichroic mirror DM which reflects the laser beam into the microscope objective lens OL and transmits the light used for both reflective and transmission light microscopy A CMOS camera in combination with a lens assembly IL is used for imaging The output of a LED LED 1 is reflected toward the mic...

Page 15: ...motions Finally a custom made sample holder tops the assembly The holder is capable of receiving microscope slides with dimensions of 75 x 25 x 1 mm The sample holder has two magnetic clamps at its ends that are used to keep the fiber steady during laser processing Moreover the sample holder accepts the output of a LED LED 2 which illuminates the sample for acquiring images by transmission light m...

Page 16: ...e 8 Lens assembly IL in the imaging setup the locations of the IL variable focus and iris knobs are highlighted Figure 9 Location of the tilt and tip adjustments of the turning mirror MT in the imaging setup ...

Page 17: ...ed A round beam pattern with a smooth intensity profile indicates instead a well aligned laser beam Care must be used when performing this task between L1 and L2 Figure 4 because of the presence of a focusing plane Figure 10 During the alignment of the laser beam within the optical layout of the vertical compartment of the femtoFBG a white piece of paper can be used to check the beam quality after...

Page 18: ... of the OL back aperture It is important to perform this task in order to take full advantage of the OL numerical aperture and hence achieve the smallest beam diameter at the OL focal plane To test the size and collimation of the laser beam after L1 and L2 a temporary mirror in a 45 mount is used before the OL to project the laser beam at a distance Figure 12 An auxiliary mirror mounted at 45 is s...

Page 19: ...g To recover this part of the system alignment the last mirror of the vertical compartment M6 Figure 4 and the DM Figure 6 are going to be used to walk the beam back to its original path The tilt and tip adjustments of M6 are used to center the laser beam in the OL back aperture The tilt and tip adjustments of the DM are used to obtain a clean and symmetric laser beam after the OL Figure 11b This ...

Page 20: ...example a PS 0 25 pedestal spacer from Newport can be used raise the OL by moving upward the manual TS Figure 6 A picture of how to perform this task is shown in Figure 14 Using the joystick move one axis of the stage assembly out as shown in Figure 15 In this new location the sample holder area is more accessible Open the MC Figure 7 and insert the microscope slide in the sample holder opening as...

Page 21: ...f the cover slip At the end of this step a uniform thin layer of index matching gel should cover the fiber to be processes with no air bubble mix in it as shown in Figure 21 A starter pack of microscope cover slips is provided with the system Set the sample on its original position by clicking Go 0 0 0 in the Move screen Remove the spacer in the manual TS Figure 6 and gently let the OL move back t...

Page 22: ...Figure 15 Moving the sample in the loading position Figure 16 Adding the microscope slide ...

Page 23: ...Figure 17 Setting the fiber to be processed in the V groves of the magnetic clamps Figure 18 Clamping down the fiber to be processes ...

Page 24: ...Figure 19 Setting the two spacers around the fiber Figure 20 Adding the index matching gel over the fiber between the two spacers ...

Page 25: ...Figure 21 Covering the whole assembly with a microscope cover slip Figure 22 The sample is position back under the OL and the spacer is removed from the manual TS ...

Page 26: ...e for the Z motion the CMOS camera two LEDs for transmission and reflective illumination a rotational stage for controlling the amount of laser average power reaching the sample the laser shuttering system and the laser emission output During laser writing the motion of the linear stages is synchronized with the laser shuttering system so to avoid laser over and under exposure at the beginning and...

Page 27: ...amount of time Duration user defined time in ms of the Burst duration P0 P1 P2 locations where to define the Z correction described in the Tools window When a coordinate is defined in x y z it can be set as one of the points for the planarization by clicking on P1 P2 or P3 Three locations are required for planarization X µm Y µm Z µm Specific locations in µm can be input for the x z and z coordina...

Page 28: ...e the sample is move in the same direction for the same length When the z axis is chosen the toggle says Stage Down When the y axis is chosen the toggle says Down and when the x axis is chosen the toggle says Left Zero when clicked it sets the current location of the sample to x 0 µm y 0 µm and z 0 µm Velocity the user can define the velocity in µm s the stages are going to be run while in the Mov...

Page 29: ... the percentage of the laser average power reaching the sample This window controls the variable attenuator within the femtoFBG vertical section Light changing the value of this bar from 0 to 100 controls the LEDs emission outputs LED1 2 clicking this toggle permits to control the immunization intensity of either LED1 or LED2 If only one LED is needed the intensity of the other LED can be set to 0...

Page 30: ...Because of the stages assembly orientation the stage that moves in the same direction of the fiber main axis is the Y one Positive By using this toggle the customer can change the direction of the FBG writing along the determined travel axis For example if the travel axis is the Y one then when positive the writing occurs towards positive values of the y axis and when negative the writing occurs t...

Page 31: ...n Y direction In a the maximum value of the Gaussian pattern is set to 95 of the laser emission while the minimum value of the Gaussian pattern is set to 0 5 of the laser emission In b the maximum value of the Gaussian pattern is set to 80 of the laser emission while the minimum value of the Gaussian pattern is set to 67 of the laser emission Figure 27 Two examples of profiles used in the design o...

Page 32: ... of a profile used in the design of a uFAB file for the fabrication of a Sinusoidal FBG 6 3 2 Sinc The Sinc profile type refers to the cardinal sine function traditionally named Sinc function Period period in µm of the sinus function Step distance in µm between points used to interpolate the Gaussian function Smaller the step distance higher is number of points used for the function interpolation ...

Page 33: ...mission respectively In a the Stretch value is set to 15 while in b it is set to 5 Figure 29 Two examples of profiles used in the design of uFAB files for the fabrication of Sinc FBGs By adjusting the stretch vertical bar the user can choose the amount of Sinc function to include within the length of the FBG In a the stretch is set to 15 while in b the stretch is set to 5 Figure 30 Example of a pr...

Page 34: ...e It controls directly the laser output power and it corresponds to the minimum laser average power used during the FBG writing An example of a FBG file using the Linear Chirp profile is shown in Figure 30 The FBG is 5 mm long in Y direction and a Step Size of 100 µm is chosen The maximum value of the Linear Chirp pattern is set to 100 of the laser emission while the minimum value of the Linear Ch...

Page 35: ...is 5 mm long in Y direction and a Step Size of 10 µm is chosen The maximum value of the Linear Chirp pattern is set to 70 of the laser emission while the minimum value of the Linear Chirp pattern is set to 20 of the laser emission 6 3 5 Chirped PVT The Chirped PVT Position Velocity Time profile type allows the formation of patterns that can be used to create chirped FBG with custom acceleration va...

Page 36: ...BG has even spacings between the grating planes and all the grating planes are made using the same writing conditions To create a file for the fabrication of uniform FBGs the Gaussian profile type is used In this particular case the Max and Min values for the laser output intensities must be chosen so to be identical The example in Figure 33 illustrates how to use the Gaussian profile type to crea...

Page 37: ...or not the laser is reaching the sample Power the reading from the femtoFBG internal power meter is displayed here A pull down menu on its right permits to change the scale of the measurement from W to µW The laser average power displayed here is not the laser average power used at the sample It is the fraction 4 of the laser average power as measured in the vertical section of the femtoFBG Select...

Page 38: ...ab Velocity this is the velocity in µm s used by the femtoFBG when laser writing is not occurring That is when the laser shutter is off Acceleration this is the acceleration in mm s2 the user can define for the two linear stages X Offset the chosen file can be fabricated with an arbitrary offset in the x direction in µm Y Offset the chosen file can be fabricated with an arbitrary offset in the y d...

Page 39: ...same structure It is a matrix with 4 repeated units in the x direction separated by 32 µm and 6 repeated united in the y direction separated by 62 µm for a total of 24 structures To accomplish this pattern the user will add 3 in the first empty Repeat box and 32 in the X Offset box that is in the same row of the Repeat box used Then in the second row the user will add 5 in the empty Repeat box and...

Page 40: ... fabrication process is provided live during the writing process For example the extent of the fabrication processes is monitored in time by showing the amount of the file in percentage already written at that moment in time The video camera and illumination controls at the bottom of the area where imaging from the CMOS camera is displayed are identical to the ones described already in the section...

Page 41: ...red change Percent Power a cursor in the vertical bar can be used to change the amount of laser average power reaching the sample This control is applied immediately Calibrate the variable power attenuator within the vertical section of the femtoFBG needs to be calibrated in order to function correctly To perform this task the user needs to open the window named Calibrate Figure 38 The calibration...

Page 42: ...three points P0 P1 and P2 Coordinates for these three points can be entered directly on the Z Correction window or replaced individually by pressing the P0 P1 or P2 button on the MOVE window Z Correction is accomplished by determining three non origin points lying on the part s surface and copying those points to TOOLS Z Correction For convenience current position can be copied to P0 or P1 or P2 b...

Page 43: ...t the wave vector of the reflected radiation totals the sum of the incident and grating wave vectors kf ki K Considering that the magnitude of the incident wave vector is identical to the one of the reflected wave vector but opposite in sign and that the grating wave vector has a magnitude of 2π ΛFBG ΛFBG is the period of the refractive index modulation the momentum conservation yields the Bragg c...

Page 44: ...s for the exposure time and gain are 41 ms and 16 respectively 7 Use the joystick to position the fiber under the microscope objective so to be visible in the live CMOS camera streaming window Often time this step can be performed while at the same looking at sample moving so to make sure to move the stages in in right direction Obviously in this case great care must be employed to avoid moving th...

Page 45: ...k Zero to set this position the new origin 0 0 0 19 Select the X axis in the Increment section Use 5000 µm as the increment to move this is the length of the FBG that will be made in this example 20 Select Right to move the stage toward the right of a distance of 5 mm In the computer screen the end point of the FBG is now visible The middle of the fiber core will not be centered on the red cross h...

Page 46: ...Figure 40 The Video Settings controls can be used to improve image quality Figure 41 When centering the fiber in the imaging the field of view the first time it will be out of focus ...

Page 47: ...igure 42 The fiber is put into focus by adjusting the manual translation stage a until the borders of the fiber core becomes clear and sharp b Figure 43 The Cross Hair button is just above the LED 1 one ...

Page 48: ...ber b 7 2 Producing the File 1 Open the Design window in the femtoFBG software 2 Choose a Gaussian Profile Type a length of 7 mm the Y axis for travel and positive direction 3 Set the velocity at 100 µm s 4 Set the step size at 10 µm and the Min and Max values of the laser emission output at 8 and 12 respectively 5 These settings will produce a profile as shown in Figure 46 6 Press Save and choose...

Page 49: ...ss Run A window as shown in Figure 47 will appear This sign indicates that the controller is preparing the file for action 6 After few seconds the writing of the FBG will begin While the writing of the FBG occurs the image of the fiber in the computer screen will be moving and the Shutter sign will show that the laser is open and focused into the fiber core Figure 48 7 It is desirable to be able t...

Page 50: ...d before the writing of the FBG begins a window indicating the file preparation by the femtoFBG controller will appears Figure 48 The top right Shutter icon in the Run window indicates the status of the shutter operation while FBG writing occurs ...

Page 51: ...Figure 49 The fabrication of FBG is best monitored using an OSA This is the spectral response of the FBG made using the file created in Section 7 ...

Page 52: ...Hz for most FBGs writing 2 Wavelength laser emission wavelength In the example described in the previous section 520 nm is used 3 Pulse Picker Divider a number larger than one in this window permits to divide the laser internal repletion by a constant effectively diminishing the number of laser pulses reaching the sample per unit time The pulse picker divider does not affect the energy per pulse w...

Page 53: ...utput 7 Power Indicator the vertical bar on the right that controls the laser emission output is not used when the Analog In is Enabled In this case the femtoFBG software overrides the laser software and it takes control of this function directly Appendix II Cabling in the femtoFBG controller The controller used with the femtoFBG is Newport XPS The following is the description of the cables leavin...

Page 54: ...ttenuator within the vertical compartment of the femtoFBG 5 Slot 5 One cable that controls the laser analog output It is connected to the laser via the analog input signal The same cable is split and the second branch goes to the SXP serial port 5 The latter enables to measure the analog output of Slot 5 Figure 52 Bottom part of the femtoFBG back panel Below the main slots are the encoders cables ...

Page 55: ... of all femtoFBG devices which are USB controlled In Figure 53 the power cord and the cable connecting it to the laptop have been removed for viewing clarity The photodiode used to monitor the amount of laser average power in the femtoFBG has is cable ending in this compartment 2 The controller 3 for the two LEDs used in the femtoFBG is in this compartment also The long cable used to connect the r...