Tunable laser materials containing solid-state polymer blends

Abstract

This invention proposes a solid-state polymer blend laser system with the ability to tune the laser wavelength by adjusting the blend ratio. This system can be used for health monitoring, environmental monitoring sensors, and tissue imaging. Current materials lack a broad tunability across the entire optical range, from blue to infrared. By using the same two polymers, a laser emitting from blue to red can be produced. This simplifies the design and integration of multi-wavelength laser sensor systems, making them cost-effective to produce.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to (1) U.S. Provisional Patent Application Serial No. 62 / 954,655, filed on December 29, 2019; and (2) U.S. Non-Provisional Patent Application Serial No. 17 / 114,463, filed on December 7, 2020, the disclosures of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to a solid-state polymer blend system having the property of tunable laser emission to different laser wavelengths by adjusting the blend ratio. Background Art

[0004] A laser system consists of a pump / excitation source, laser material, and a feedback structure, typically a gain medium and an optical resonator. Here is a brief description of these components:

[0005] 1. Pump / excitation source: This is the energy source that provides excitation energy to the gain medium. Generally speaking, the pump source can be an electric current injection or a light source such as a laser or flash lamp.

[0006] 2. Gain medium: This is the laser material, which can be inorganic or organic. The gain medium absorbs most of the excitation energy and emits laser light.

[0007] 3. Optical resonant cavity: The gain medium is placed inside the optical resonant cavity, which limits the stimulated emission so that it can accumulate to the intensity required to become a laser.

[0008] Laser processing

[0009] When excited, laser materials initially emit photoluminescence (PL), light-induced luminescence, a process known as spontaneous emission. Then, with increasing excitation, emission shifts to a process known as amplified spontaneous emission (ASE). With further excitation, the emission becomes stimulated emission, often referred to as lasing. The difference in optical properties between ASE and lasers is not significant in optoelectronic / photonic applications, so they are often classified as lasers.

[0010] Emission characteristics

[0011] Emission characteristics are defined by the width of its emission spectrum, measured as the full width at half maximum (FWHM), which is half the maximum intensity. PL has a broad emission FWHM, typically 20-50 nm. ASE has a FWHM of 5-10 nm, and lasers typically have a FWHM less than 5 nm.

[0012] Most inorganic or organic solid-state lasers only emit at a single wavelength, but generating tunable laser emission over a wide wavelength range, such as the optical range of a single organic system, has not yet been achieved. Current approaches to tunable laser systems use feedback structure design, the Burstein-Moss effect, and bandgap engineering. Summary of the Invention

[0013] Therefore, one of the objectives of the present invention is to produce a solid-state polymer blend system with tunable laser wavelength characteristics by adjusting the blend ratio, which can be used for health monitoring, environmental monitoring sensors and tissue imaging. Current materials do not have a wide tunability range across the entire optical range, from blue light to infrared light. By using the same two polymers, a laser that can emit blue to red light can be produced. This simplifies the design and integration of multi-wavelength laser sensor systems, making production cost-effective.

[0014] In a first aspect of the present invention, a solid-state polymer blend laser system is provided, the laser wavelength of which can be adjusted by changing the blending ratio of the polymer compounds in the polymer blend laser system, the polymer compound comprising a mixture of at least two polymer compounds, including poly(9,9-dioctylfluorene) (PFO), poly(2-(2',5'-bis(2'-ethylhexyloxy)phenyl)-1,4-phenylenevinylene) (BEHP-PPV) and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV).

[0015] In a first embodiment of the first aspect of the present invention, a solid-state blended polymer laser system is provided, wherein the mixture of at least two polymer compounds is a mixture of poly(9,9-dioctylfluorene) and poly(2-(2',5'-bis(2'-ethylhexyloxy)phenyl)-1,4-phenylene vinylene), or a mixture of poly(2-(2',5'-bis(2'-ethylhexyloxy)phenyl)-1,4-phenylene vinylene) and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene].

[0016] In a second embodiment of the first aspect of the present invention, a solid-state blended polymer laser system is provided, wherein the blending ratio of at least two polymer compounds in the blended polymer laser system is equal to or greater than 0.01:99.99, and the main component of the mixture of the at least two polymer compounds is poly(2-(2',5'-bis(2'-ethylhexyloxy)phenyl)-1,4-phenylene vinylene).

[0017] In a third embodiment of the first aspect of the present invention, a solid-state blended polymer laser system is provided, wherein the blending ratio of at least two polymer compounds in the blended polymer laser system is equal to or lower than 40:60, and the main component of the mixture of the at least two polymer compounds is poly(2-(2',5'-bis(2'-ethylhexyloxy)phenyl)-1,4-phenylene vinylene).

[0018] In the fourth embodiment of the first aspect of the present invention, a solid-state blended polymer laser system is provided, wherein the blending ratio of at least two polymer compounds in the blended polymer laser system is equal to or higher than 0.1:99.9, and the main component of the mixture of the at least two polymer compounds is poly(9,9-dioctylfluorene).

[0019] In the fifth embodiment of the first aspect of the present invention, a solid-state blended polymer laser system is provided, wherein the blending ratio of at least two polymer compounds in the blended polymer laser system is equal to or lower than 40:60, and the main component of the mixture of the at least two polymer compounds is poly(9,9-dioctylfluorene).

[0020] In the sixth embodiment of the first aspect of the present invention, a solid-state blended polymer laser system is provided, wherein the blending ratio of at least two polymer compounds in the blended polymer laser system is equal to or higher than 0.01:99.99, and the minor component of the mixture of the at least two polymer compounds is poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene].

[0021] In the seventh embodiment of the first aspect of the present invention, a solid-state blended polymer laser system is provided, wherein the blending ratio of at least two polymer compounds in the blended polymer laser system is equal to or lower than 40:60, and the minor component of the mixture of the at least two polymer compounds is poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene].

[0022] In the eighth embodiment of the first aspect of the present invention, a solid-state blended polymer laser system is provided, wherein the blending ratio of at least two polymer compounds in the blended polymer laser system is equal to or higher than 0.1:99.9, and the minor component of the mixture of the at least two polymer compounds is poly(2-(2',5'-bis(2'-ethylhexyloxy)phenyl)-1,4-phenylene vinylene).

[0023] In the ninth embodiment of the first aspect of the present invention, a solid-state blended polymer laser system is provided, wherein the blending ratio of at least two polymer compounds in the blended polymer laser system is equal to or lower than 40:60, and the minor component of the mixture of the at least two polymer compounds is poly(2-(2',5'-bis(2'-ethylhexyloxy)phenyl)-1,4-phenylene vinylene).

[0024] In a tenth embodiment of the first aspect of the present invention, a solid-state blend polymer laser system is provided, which further comprises a DFB feedback structure integrated with different grating periods to provide different tunable laser outputs.

[0025] In an eleventh embodiment of the first aspect of the present invention, a solid-state blended polymer laser system is provided, wherein one of the grating periods is 270 nm; one of the at least two polymer compounds is poly(9,9-dioctylfluorene); and the corresponding wavelength of the tunable laser output varies from 439 nm to 456 nm.

[0026] In a twelfth embodiment of the first aspect of the present invention, a solid-state blend polymer laser system is provided, wherein one of the grating periods is 340 nm; two of the at least two polymer compounds are poly(9,9-dioctylfluorene) and poly(2-(2',5'-bis(2'-ethylhexyloxy)phenyl)-1,4-phenylenevinylene); and the corresponding wavelength of the tunable laser output varies from 500 nm to 541 nm.

[0027] In a thirteenth embodiment of the first aspect of the present invention, a solid-state blend polymer laser system is provided, wherein one of the grating periods is 415 nm; two of the at least two polymer compounds are poly(2-(2',5'-bis(2'-ethylhexyloxy)phenyl)-1,4-phenylenevinylene) and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]; and the corresponding wavelength of the tunable laser output varies from 600 nm to 644 nm.

[0028] In a fourteenth embodiment of the first aspect of the present invention, a solid-state polymer blend laser system is provided, wherein the polymer blend laser system forms one or more polymer blend films with a thickness of 120 nm to 195 nm.

[0029] In a fifteenth embodiment of the first aspect of the present invention, a solid-state polymer blend laser system is provided, wherein the one or more polymer blend films are deposited on a quartz substrate by spin coating a solution mixture of the at least two polymer compounds.

[0030] Throughout this specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising" will be understood to include the recited entity or group of entities but not to exclude any other entity or group of entities. It is also important to note that in this disclosure, and particularly in the claims and / or paragraphs, certain terms such as "comprises," "comprised," "comprising," and similar terms may have the meanings ascribed to them under U.S. patent law. For example, these terms may mean "includes," "included," "including," and similar terms; and terms such as "consisting essentially of" and "consists essentially of" have the meanings ascribed to them under U.S. patent law. For example, they allow for inclusion of elements not expressly recited but exclude elements that are available in the prior art or that affect the basic or novel characteristics of the invention.

[0031] Furthermore, throughout this specification and claims, unless the context requires otherwise, the word “include” or variations such as “includes” or “including” shall be understood to include the stated entity or group of entities but not to exclude any other entity or group of entities.

[0032] Other definitions of alternative terms used herein can be found in the detailed description of the invention and translated throughout. Unless otherwise defined, all other technical terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the invention belongs.

[0033] Other aspects and advantages of the present invention will be apparent to those of ordinary skill in the art after reviewing the ensuing description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will become more apparent from the following description of the invention taken in conjunction with the accompanying drawings, in which:

[0035] Figure 1 Shown are the chemical structures of poly(9,9-dioctylfluorene) (PFO), poly(2-(2',5'-bis(2'-ethylhexyloxy)phenyl)-1,4-phenylenevinylene) (BEHP-PPV), and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV).

[0036] Figure 2A Shown are the FWHM (filled squares) and output intensity (filled spheres) of the PFO sample emission spectrum as a function of pump fluence. ASE thresholds are estimated with and without accounting for transmission losses.

[0037] Figure 2B Shown are the emission spectra of the planar waveguide of the PFO sample with various pump fluxes.

[0038] Figure 3A Shown are plots of the output intensity of the BEHP-PPV samples (solid squares and spheres, with and without polarizers) versus pump fluence.

[0039] Figure 3B Shown are the emission spectra of the planar waveguide of the BEHP-PPV sample (without polarizer) with various pump fluxes.

[0040] Figure 4 Shown are the absorbance and PL spectra of BEHP-PPV and MEH-PPV. Significant spectral overlap exists between the absorption spectrum of MEH-PPV and the PL spectrum of BEHP-PPV, which is expected to result in efficient energy transfer from BEHP-PPV to MEH-PPV.

[0041] Figure 5 Shown is a plot of film thickness versus mixing concentration.

[0042] Figure 6A Shown are the transmission spectra of pure films of a BEHP-PPV:MEH-PPV blend. The MEH-PPV concentration was varied from 0.01% to 0.4%. Also shown are the transmission spectra of pure BEHP-PPV and MEH-PPV films.

[0043] Figure 6B Shown are the transmission spectra of BEHP-PPV:MEH-PPV blends in neat membranes. The MEH-PPV concentration was varied from 0.8% to 8%. Also shown are the transmission spectra of neat BEHP-PPV and MEH-PPV membranes.

[0044] Figure 6C Shown are the transmission spectra of BEHP-PPV:MEH-PPV blends in neat membranes. The MEH-PPV concentration was varied from 10% to 40%. Also shown are the transmission spectra of neat BEHP-PPV and MEH-PPV membranes.

[0045] Figure 6DShown are the absorption spectra of BEHP-PPV:MEH-PPV blends in neat membranes. The MEH-PPV concentration was varied from 0.01% to 0.4%. Also shown are the absorption spectra of neat BEHP-PPV and MEH-PPV membranes.

[0046] Figure 6E Shown are the absorption spectra of BEHP-PPV:MEH-PPV blends in neat membranes. The MEH-PPV concentration was varied from 0.8% to 8%. Also shown are the absorption spectra of neat BEHP-PPV and MEH-PPV membranes.

[0047] Figure 6F Shown are the absorption spectra of BEHP-PPV:MEH-PPV blends in neat membranes. The MEH-PPV concentration ranges from 10% to 40%. Also shown are the absorption spectra of neat BEHP-PPV and MEH-PPV membranes.

[0048] Figure 6G Shown are the spectral absorption coefficients of BEHP-PPV:MEH-PPV blends in pure membranes. The MEH-PPV concentration was varied from 4% to 40%.

[0049] Figure 7A Shown are the PL spectra of BEHP-PPV:MEH-PPV blends. The MEH-PPV concentration ranged from 0.01% to 1%. Also shown is the PL spectrum of a pure BEHP-PPV film.

[0050] Figure 7B Shown are the PL spectra of BEHP-PPV:MEH-PPV mixed samples. The concentration of MEH-PPV was varied from 2% to 40%.

[0051] Figure 7C Shown are the PL spectra (normalized by the maximum value) of a BEHP-PPV:MEH-PPV blend. The MEH-PPV concentration was varied from 0.01% to 1%. Also shown is the PL spectrum (normalized by the maximum value) of a pure BEHP-PPV film.

[0052] Figure 7D Shown are the PL spectra of BEHP-PPV:MEH-PPV mixed samples (normalized by the maximum value). The concentration of MEH-PPV was varied from 2% to 40%.

[0053] Figure 7EShown are the PL spectra (normalized by area) of a BEHP-PPV:MEH-PPV blend. The MEH-PPV concentration was varied from 0.01% to 1%. Also shown is the PL spectrum (normalized by maximum value) of a pure BEHP-PPV film.

[0054] Figure 7F Shown are the PL spectra of BEHP-PPV:MEH-PPV mixed samples (normalized by the maximum value). The concentration of MEH-PPV was varied from 2% to 40%.

[0055] Figure 8 Shown is the relationship between the PL quantum yield (PLQY) value of the blend film excited at 390 nm and the MEH-PPV concentration.

[0056] Figure 9A Shown are the ASE results for a hybrid sample with a 0.01% MEH-PPV concentration during optical amplification near 525 nm. The full width at half maximum (FWHM) of the emission spectrum (filled squares) and the output intensity of the hybrid sample (filled spheres) are shown as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0057] Figure 9B Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 0.01%.

[0058] Figure 9C Shown are the ASE results for a hybrid sample with a 0.02% MEH-PPV concentration during optical amplification near 525 nm. The full width at half maximum (FWHM) of the emission spectrum (filled squares) and the output intensity of the hybrid sample (filled spheres) are shown as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0059] Figure 9D Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 0.02%.

[0060] Figure 9E Shown are the ASE results for a hybrid sample with a 0.04% MEH-PPV concentration during optical amplification near 525 nm. The full width at half maximum (FWHM) of the emission spectrum (filled squares) and the output intensity of the hybrid sample (filled spheres) are shown as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0061] Figure 9F Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 0.04%.

[0062] Figure 10AShown are the ASE results for a hybrid sample with a 0.1% MEH-PPV concentration during dual-wavelength optical amplification at 524 nm and 563 nm. The output intensity (solid squares and spheres) of the hybrid sample with a 0.1% MEH-PPV fraction at different amplification peaks is plotted as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0063] Figure 10B Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 0.1%.

[0064] Figure 11A Shown are the ASE results for a hybrid sample with a 0.2% MEH-PPV concentration during optical amplification near 570 nm. The full width at half maximum (FWHM) of the emission spectrum (filled squares) and the output intensity of the hybrid sample (filled spheres) are shown as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0065] Figure 11B Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 0.2%.

[0066] Figure 11C Shown are the ASE results for a hybrid sample with a 0.4% MEH-PPV concentration during optical amplification near 570 nm. The full width at half maximum (FWHM) of the emission spectrum (filled squares) and the output intensity of the hybrid sample (filled spheres) are shown as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0067] Figure 11D Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 0.4%.

[0068] Figure 11E Shown are the ASE results for a hybrid sample with a 0.8% MEH-PPV concentration during optical amplification near 570 nm. The full width at half maximum (FWHM) of the emission spectrum (filled squares) and the relative output intensity of the hybrid sample (filled spheres) are plotted as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0069] Figure 11F Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 0.8%.

[0070] Figure 11GShown are the ASE results for a hybrid sample with a 1% MEH-PPV concentration during optical amplification near 570 nm. The FWHM of the emission spectrum (filled squares) and the output intensity of the hybrid sample (filled spheres) are shown as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0071] Figure 11H Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 1%.

[0072] Figure 11I Shown are the ASE results for a hybrid sample with a 2% MEH-PPV concentration during optical amplification near 570 nm. The full width at half maximum (FWHM) of the emission spectrum (filled squares) and the output intensity of the hybrid sample (filled spheres) are shown as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0073] Figure 11J Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 2%.

[0074] Figure 12A Shown are the ASE results for a hybrid sample with a 4% MEH-PPV concentration during optical amplification at approximately 610 nm (±10 nm). The full width at half maximum (FWHM) of the emission spectrum (filled squares) and the output intensity of the hybrid sample (filled spheres) are shown as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0075] Figure 12B Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 4%.

[0076] Figure 12C Shown are the ASE results for a hybrid sample with a 6% MEH-PPV concentration during optical amplification at approximately 610 nm (±10 nm). The full width at half maximum (FWHM) of the emission spectrum (filled squares) and the output intensity of the hybrid sample (filled spheres) are shown as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0077] Figure 12D Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 6%.

[0078] Figure 12EShown are the ASE results for a hybrid sample with an 8% MEH-PPV concentration during optical amplification at approximately 610 nm (±10 nm). The full width at half maximum (FWHM) of the emission spectrum (filled squares) and the output intensity of the hybrid sample (filled spheres) are shown as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0079] Figure 12F Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 8%.

[0080] Figure 12G Shown are the ASE results for a hybrid sample with a 10% MEH-PPV concentration during optical amplification at approximately 610 nm (±10 nm). The full width at half maximum (FWHM) of the emission spectrum (filled squares) and the output intensity of the hybrid sample (filled spheres) are shown as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0081] Figure 12H Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 10%.

[0082] Figure 12I Shown are the ASE results for a hybrid sample with a 12% MEH-PPV concentration during optical amplification at approximately 610 nm (±10 nm). The full width at half maximum (FWHM) of the emission spectrum (filled squares) and the output intensity of the hybrid sample (filled spheres) are shown as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0083] Figure 12J Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 12%.

[0084] Figure 12K Shown are the ASE results for a hybrid sample with a 16% MEH-PPV concentration during optical amplification at approximately 610 nm (±10 nm). The full width at half maximum (FWHM) of the emission spectrum (filled squares) and the output intensity of the hybrid sample (filled spheres) are shown as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0085] Figure 12L Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 16%.

[0086] Figure 12MShown are the ASE results for a hybrid sample with a 20% MEH-PPV concentration during optical amplification at approximately 610 nm (±10 nm). The full width at half maximum (FWHM) of the emission spectrum (filled squares) and the output intensity of the hybrid sample (filled spheres) are shown as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0087] Figure 12N Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 20%.

[0088] Figure 12O Shown are the ASE results for a hybrid sample with a 40% MEH-PPV concentration during optical amplification at approximately 610 nm (±10 nm). The full width at half maximum (FWHM) of the emission spectrum (filled squares) and the output intensity of the hybrid sample (filled spheres) are shown as a function of pump fluence. The ASE threshold is estimated with and without accounting for transmission losses.

[0089] Figure 12P Shown is the emission spectrum of the planar waveguide of the mixed sample with a MEH-PPV concentration of 40%.

[0090] Figure 13A Shown is the ex Figure 3. ASE threshold energy (excluding transmission loss) versus MEH-PPV fraction for a blend pumped at λ = 355 nm. MEH-PPV fractions in the blends were 0.01%, 0.02%, 0.04%, 0.1%, 0.2%, 0.4%, 0.8%, 1%, 2%, 4%, 6%, 8%, 10%, 12%, 16%, 20%, and 40%.

[0091] Figure 13B Shown is the relationship between the ASE center wavelength of the mixed sample and the MEH-PPV concentration.

[0092] Figure 14 The tunable ASE spectrum of the BEHP-PPV:MEH-PPV blend is shown, with emission wavelengths ranging from 520 nm to 610 nm. ex =355 nm pump out.

[0093] Figure 15A Shown is the ex = 355 nm pumped blend system ASE energy threshold (not considering transmission loss) and MEH-PPV fraction. Results were pumped by another laser system.

[0094] Figure 15BThe plot shows the relationship between the ASE center wavelength and the MEH-PPV concentration of the mixed sample. The results were pumped by another laser system.

[0095] Figure 16 Shown are the absorbance and PL spectra of PFO and BEHP-PPV. Significant spectral overlap exists between the absorption spectrum of BEHP-PPV and the PL spectrum of PFO, which is expected to result in efficient energy transfer from PFO to BEHP-PPV.

[0096] Figure 17A Shown are the transmission spectra of PFO:BEHP-PPV blends in neat films. The BEHP-PPV concentration ranges from 0.1% to 2%. Also shown is the transmission spectrum of a neat PFO film. The P:B number indicates the concentration ratio of PFO to BEHP-PPV.

[0097] Figure 17B Shown are the transmission spectra of PFO:BEHP-PPV blends in neat films. The BEHP-PPV concentration ranged from 3% to 40%. The P:B numbers indicate the concentration ratio of PFO to BEHP-PPV.

[0098] Figure 17C Shown are the transmittance spectra of PFO:BEHP-PPV blends in pure membranes. The BEHP-PPV concentration ranges from 0.1% to 2%. Also shown are the normalized absorbance spectra of the pure PFO membrane. The P:B numbers indicate the concentration ratio of PFO to BEHP-PPV.

[0099] Figure 17D Shown are the normalized absorption spectra of PFO:BEHP-PPV blends in pure membranes. BEHP-PPV concentrations ranged from 3% to 40%. The P:B numbers indicate the PFO to BEHP-PPV concentration ratio.

[0100] Figure 18A Shown are the PL spectra (normalized by area) of a PFO:BEHP-PPV blend. The BEHP-PPV concentration was varied from 0.1% to 2%. Also shown are the PL spectra (normalized by area) of a pure PFO film. The P:B number indicates the concentration ratio of PFO to BEHP-PPV.

[0101] Figure 18B Shown are the PL spectra of PFO:BEHP-PPV mixed samples (normalized by area). The concentration of BEHP-PPV was varied from 3% to 40%. The P:B numbers indicate the concentration ratio of PFO to BEHP-PPV.

[0102] Figure 19Shown are the PLQY values of PFO:BEHP-PPV blend films excited at 390 nm as a function of BEHP-PPV concentration.

[0103] Figure 20 Shown are multiple ASE spectra of PFO:BEHP-PPV blends, with emission wavelengths between 450 nm and 520 nm. The P:B numbers represent the concentration ratio of PFO to BEHP-PPV.

[0104] Figure 21 Shown are the tunable blue laser wavelength generated by varying the PFO polymer film thickness (film thickness varied from 100 nm to 200 nm; identical distributed feedback (DFB) grating with a period of 270 nm) in the top panel and the corresponding wavelength variation of the pump laser energy density threshold of the PFO DFB laser in the bottom panel.

[0105] Figure 22 Shown are the tunable green laser wavelength generated by varying the PFO:BEHP-PPV 60:40 polymer film thickness (film thickness varied from 100 nm to 500 nm; identical DFB grating with a period of 340 nm) in the top panel and the corresponding wavelength variation of the pump laser fluence threshold of the blended PFO:BEHP-PPV (60:40) DCB laser in the bottom panel. The P:B numbers indicate the concentration ratio of PFO to BEHP-PPV.

[0106] Figure 23 Shown are the tunable red laser wavelength generated by varying the thickness of the BEHP-PPV:MEH-PPV 90:10 polymer film (film thickness varied from 100 nm to 500 nm; identical DFB grating with a period of 415 nm) in the top panel and the corresponding wavelength variation of the pump laser fluence threshold of the blended BEHP-PPV:MEH-PPV (90:10) DCB laser in the bottom panel. The numbers in B:M indicate the concentration ratio of BEHP-PPV to MEH-PPV.

[0107] Figure 24 Shown is a graph showing the output power versus input power of a blended BEHP-PPV:MEH-PPV (90:10) DFB laser with lasing output at 619 nm. DETAILED DESCRIPTION

[0108] The present invention is not limited in scope to any specific embodiment described herein. The following embodiments are presented for illustration only.

[0109] Organic gain media

[0110] Poly(9,9-dioctylfluorene) (PFO) was selected as one of the polymer blends for blue emission. Poly(2-(2',5'-bis(2'-ethylhexyloxy)phenyl)-1,4-phenylenevinylene) (BEHP-PPV) and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) were selected as two polymers for green to red emission. Figure 1 Certain materials / compounds may exhibit lasing or ASE when in solution. In solution, these materials / compounds are physically separate and therefore behave as individual particles. However, in solid form, these materials, which can be compounds (e.g., molecules) or atoms, can become densely packed. In this case, they interact with each other; one consequence of this close contact is that any luminescence, including lasing and ASE, can be terminated. Therefore, a material exhibiting ASE / lasing properties in solution does not necessarily exhibit this behavior in the solid state. This phenomenon is well-established in the scientific community.

[0111] Materials and Methods

[0112] Measuring ASE

[0113] For ASE measurements (unspecified), a Q-switched Nd-YAG laser (3 nanoseconds, 355 nanometers, 7500 Hz) was used to provide pump energy, with a chopper achieving a chopping frequency of 18 Hz. The laser beam was transformed by a cylindrical lens to form a 5.0 mm × 0.40 mm stripe-shaped excitation region. ASE edge emission was monitored using an Ocean Optics USB4000.

[0114] The lasing / ASE threshold is a key parameter of laser / amplifier devices, defining the state where gain equals resonator and waveguide losses. A low lasing / ASE threshold is always a requirement in laser device engineering, as it means lowering the energy required for lasing / amplification. Regarding ASE, the threshold is dependent on factors such as waveguide quality, gain material, and laser pulse width. Under similar pumping conditions, the thresholds of different materials can be compared to help select the most suitable gain material for the laser device.

[0115] The threshold of the PFO membrane is about 11.2 μJ / cm 2 ( Figure 2A Compared with other reports, this result is credible (slightly lower, mainly due to the smaller pulse width in the device). The ASE peak corresponding to the PFO planar waveguide is 449 nm ( Figure 2B The threshold of BEHP-PPV membrane is about 26.1μJ / cm 2 ( Figure 3A Regarding energy input, the threshold is approximately 11.7 μJ / cm 2The ASE peak corresponding to the BEHP-PPV planar waveguide is 524 nm ( Figure 3B The inventors did not obtain a narrow spectrum of MEH-PPV at 355 nm, mainly because its absorption at 355 nm was very low.

[0116] Host-guest energy transfer system for tunable amplification

[0117] The polymers BEHP-PPV and MEH-PPV share a common molecular backbone, PPV. The PL peak of BEHP-PPV is at 487 nm. The quantum efficiency of a pure BEHP-PPV film excited at 390 nm is 20%. For BEHP-PPV, the absorption peak is at 416 nm and drops sharply to zero at 491 nm. The PL of MEH-PPV peaks at 575 nm. The quantum efficiency of a pure MEH-PPV film excited at 390 nm is 9%. For MEH-PPV, the absorption peak is at 488 nm and drops to zero at 600 nm. Figure 4 ).

[0118] The emission spectrum of BEHP-PPV is in good agreement with the absorption spectrum of MEH-PPV. Efficient energy transfer from BEHP-PPV to MEH-PPV is expected via FRET ( Figure 4 ).

[0119] BEHP-PPV:MEH-PPV blend system

[0120] A blend solution was prepared by mixing the polymer solutions (BEHP-PPV and MEH-PPV). The BEHP-PPV concentration was 22 mg / mL. Depending on the mixing conditions, MEH-PPV concentrations could be selected at 0.1 mg / mL, 0.5 mg / mL, 2 mg / mL, or 8 mg / mL. The mixed solution was heated to 50-90°C and stirred at 200-1000 rpm. The blend components are listed in Table 1.

[0121] Table 1: Mixture ingredients

[0122]

[0123] The blended polymer film was deposited by spin coating the mixed solution on a quartz substrate. The spin coating speed was between 500 rpm and 8000 rpm. The acceleration rate was between 500 rpm / s and 4000 rpm / s. The thickness of the mixed sample is listed in Table 2. The film thickness of the mixed sample was about 150 ± 40 nm (Table 2 and Figure 5 ), which is suitable for forming waveguide structures for ASE measurements in these films.

[0124] Table 2: Concentration of mixed samples

[0125]

[0126] The transmission and absorption spectra of these mixed samples are related to the transmission and absorption signals of BEHP-PPV and MEH-PPV ( Figures 6A to 6G The fluorescence of MEH-PPV gradually increases with the increase of MEH-PPV ratio, which represents the energy transfer in this process ( Figures 7A to 7F PLQY values range from 9% to 22% ( Figure 8 ).

[0127] By precisely modulating the mixing ratio, tunable light amplification can be demonstrated in the hybrid system. The following lists the results of tunable ASE wavelength using different MEH-PPV concentrations:

[0128] - The light amplification at around 525 nm was observed between 0% and 0.04% MEH-PPV concentration. Figures 9A to 9F );

[0129] - When the concentration of MEH-PPV is 0.1%, the dual wavelength optical amplification at 524 nm and 563 nm ( Figures 10A to 10B );

[0130] - The light amplification at around 570 nm was observed between 0.2% and 2% MEH-PPV concentrations. Figures 11A to 11J );

[0131] - The light amplification at 610 nm (±10 nm) was observed for MEH-PPV concentrations between 4% and 40%. Figures 12A to 12P ).

[0132] In different light amplification bands, the ASE threshold varies. In the blend system, the lowest green ASE threshold shown in the blend -0.01% is 15.2μJ / cm 2 The lowest yellow ASE threshold exhibited by the blend -1% was 16.2 μJ / cm 2 The lowest red ASE threshold exhibited by the blend -4% was 4.5 μJ / cm 2 ( Figure 13A ). The corresponding ASE peaks at different MEH-PPV concentrations are as follows Figure 13B shown.

[0133] By using other laser devices such as Nd-YAG laser (5 ns, 355 nm, 10 Hz) as pump source, tunable optical amplification from green to red (green ASE, green + yellow ASE, yellow ASE, yellow + red ASE, red ASE) was also demonstrated in the BEHP-PPV:MEH-PPV hybrid system ( Figure 14 ). Figure 15A and 15B The corresponding ASE threshold and peak values at different MEH-PPV concentrations are shown, respectively.

[0134] The second blend polymer system: PFO:BEHP-PPV blend system

[0135] There is a significant spectral overlap between the absorption spectrum of BEHP-PPV and the PL spectrum of PFO, which is expected to lead to efficient energy transfer from PFO to BEHP-PPV ( Figure 16 ).

[0136] A PFO:BEHP-PPV blend solution was prepared using a similar method to that used to mix polymer solutions of PFO and BEHP-PPV. The blend solution was heated to 50-90°C and stirred at 200-1000 rpm. The blend polymer film was deposited by spin coating the blend solution onto a quartz substrate. The spin coating speed ranged from 500 rpm to 8000 rpm, and the acceleration rate ranged from 500 rpm / s to 4000 rpm / s. The film thickness of the blend sample was approximately 130 ± 10 nm.

[0137] The transmission and absorption spectra of these mixed samples are related to the transmission and absorption signals of PFO and BEHP-PPV ( Figures 17A to 17D ). BEHP-PPV fluorescence gradually increases with the increase of BEHP-PPV ratio, which represents the energy transfer in this process ( Figures 18A to 18B PLQY values range from 32% to 57% ( Figure 19 ).

[0138] Tunable optical amplification with ASE wavelength from 450 nm to 520 nm was demonstrated in a PFO:BEHP-PPV hybrid system. Figure 20 ).

[0139] Tunable DFB laser in hybrid system

[0140] By integrating a DFB feedback structure with a grating period of 270 nm, the PFO DFB laser device showed tunable blue laser output with a wavelength ranging from 439 nm to 456 nm ( Figure 21 ). The minimum lasing threshold is ca.38nJ per pulse.

[0141] By integrating a DFB feedback structure with a grating period of 340 nm, the PFO:BEHP-PPV 60:40 DFB laser device showed tunable green laser output with a wavelength ranging from 500 nm to 541 nm ( Figure 22). The minimum lasing threshold is ca.5nJ per pulse.

[0142] By integrating a DFB feedback structure with a grating period of 415 nm, the BEHP-PPV:MEH-PPV DFB laser device showed tunable red laser output with a wavelength ranging from 600 nm to 644 nm ( Figure 23 The lowest lasing threshold is ca.6nJ per pulse. For example, a BEHP-PPV:MEH-PPV (90:10) hybrid sample emitting at 619 nm exhibited DFB laser output with a large-area grating (1.2 mm × 1.2 mm). When the pump power was 62 μW, the output power was greater than 1 μW. The laser output slope efficiency was <1.6% ( Figure 24 ).

[0143] Industrial Applicability

[0144] The present invention relates to a polymer blend system that has the property of tunable laser wavelength by adjusting the blend ratio, which can be used for health monitoring, environmental monitoring sensors and tissue imaging. In these applications, the detection of gases, pollutants and biological tissues often requires the use of a wide range of emitted light. Currently used materials do not have a wide tunability range across the entire optical range, from blue light to infrared light. By using the same two polymers, it is possible to produce laser light that can emit from blue to red. This simplifies the design and integration of multi-wavelength laser sensor systems, making production cost-effective.

[0145] From the foregoing description, those skilled in the art will appreciate that the broad techniques of the embodiments can be implemented in a variety of forms. Therefore, although the embodiments have been described in conjunction with specific examples thereof, this is not intended to limit the true scope thereof, as other modifications will become apparent to those skilled in the art upon study of the drawings, the specification, and the appended claims.

Claims

1. A solid-state polymer blend laser system, wherein the laser emission is tuned to different laser wavelengths by adjusting the blend ratio, The polymer blend comprises a mixture of at least two high molecular weight compounds, wherein the at least two high molecular weight compounds comprise poly(9,9-dioctylfluorene) and poly(2-(2',5'-bis(2'-ethylhexyloxy)phenyl)-1,4-phenylenevinylene).

2. The solid-state polymer blend laser system according to claim 1, wherein: The blending ratio of at least two polymer compounds in the blended polymer laser system is equal to or greater than 0.01:99.99, and the main component of the mixture of the at least two polymer compounds is poly(2-(2',5'-bis(2'-ethylhexyloxy)phenyl)-1,4-phenylene vinylene).

3. The solid-state polymer blend laser system according to claim 1, wherein: The blending ratio of at least two polymer compounds in the blended polymer laser system is equal to or lower than 40:60, and the main component of the mixture of the at least two polymer compounds is poly(2-(2',5'-bis(2'-ethylhexyloxy)phenyl)-1,4-phenylene vinylene).

4. The solid-state polymer blend laser system according to claim 1, wherein: The blending ratio of at least two polymer compounds in the blended polymer laser system is equal to or higher than 0.1:99.9, and the main component of the mixture of the at least two polymer compounds is poly (9,9-dioctylfluorene).

5. The solid-state polymer blend laser system according to claim 1, wherein: The blending ratio of at least two polymer compounds in the blended polymer laser system is equal to or lower than 40:60, and the main component of the mixture of the at least two polymer compounds is poly (9,9-dioctylfluorene).

6. The solid-state polymer blend laser system of claim 1, wherein: The invention further comprises a DFB feedback structure integrating different grating periods to provide different adjustable laser outputs.

7. The solid-state polymer blend laser system of claim 6, wherein: One of the grating periods is 270 nm; and the corresponding wavelength of the tunable laser output varies from 439 nm to 456 nm.

8. The solid-state blend polymer laser system of claim 6, wherein: One of the grating periods is 340 nm; and the corresponding wavelength of the tunable laser output varies from 500 nm to 541 nm.

9. The solid-state polymer blend laser system of claim 1, wherein: The polymer blend laser system forms one or more polymer blend films with a thickness of 120 nm to 195 nm.

10. The solid-state polymer blend laser system of claim 9, wherein: The one or more polymer blend films are deposited on a quartz substrate by spin coating a solution mixture of the at least two polymer compounds.

Images