Microwave-to-optical conversion using lithium niobate thin-film acoustic resonators

Abstract

We demonstrate conversion of up to 4.5 GHz-frequency microwaves to 1500 nm-wavelength light using optomechanical interactions on suspended thin-film lithium niobate. Our method utilizes an interdigital transducer that drives a free-standing 100 µm-long thin-film acoustic resonator to modulate light travelling in a Mach-Zehnder interferometer or racetrack cavity. Owing to the strong microwave-to-acoustic coupling offered by the transducer in conjunction with the strong photoelastic, piezoelectric, and electro-optic effects of lithium niobate, we achieve a half-wave voltage of V π = 4.6 V and V π = 0.77 V for the Mach-Zehnder interferometer and racetrack resonator, respectively. The acousto-optic racetrack cavity exhibits an optomechancial single-photon coupling strength of 1.1 kHz. Our integrated nanophotonic platform coherently leverages the compelling properties of lithium niobate to achieve microwaveto-optical transduction. To highlight the versatility of our system, we also demonstrate a lossless microwave photonic link, which refers to a 0 dB microwave power transmission over an optical channel.

Reconfigurable non-reciprocal acousto-optic modulator

“…When stimulated, the IDT necessarily launches acoustic waves outwards with both +q and −q wave vectors in opposite directions. Depending on the physical placement of the photonic device in relation to the IDT, only one of these wave vectors may be utilized [17,[29][30][31], or a standing wave may be utilized [32,33], either of which cannot be changed once fabricated. Moreover, while unidirectional IDT designs (i.e.…”

Rejuvenating a Versatile Photonic Material: Thin‐Film Lithium Niobate

“…In recent years, based on this rapidly-growing technology, a plethora of ultracompact integrated photonic devices and circuits, such as microdisk [59][60][61][62] and microring [46,[63][64][65][66] resonators, EO modulators, [67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84][85] acousto-optic modulators, [86][87][88][89] photodetector, [90] integrated single-photon detector, [91] grating couplers, [92][93][94][95][96] fiber-to-chip edge couplers, [97][98][99] wavelength Figure 2. Summary of the steps for fabrication of TFLN on Si wafers.…”

Integrated microwave acousto-optic frequency shifter on thin-film lithium niobate

“…Integrated acousto-optic or Brillouin scattering devices [1] have enabled a wide range of applications including frequency shifting [2][3][4][5], microwave-to-optical conversion (modulation) [6][7][8][9][10][11], microwave photonic filtering [12], frequency comb generation [13], pulse shaping [14], ultra-narrow-linewidth lasing [15,16], and nonreciprocal transmission [17][18][19][20][21][22][23]. Such integrated devices employ photoelasticity and optical confinement of thin-film materials such as silicon [16,17,[19][20][21], silicon nitride [15], aluminum nitride [4,5,14,22,23], gallium arsenide [6], arsenic trisulfide [12], lithium tantalate [13], and lithium niobate (LN) [7][8][9][10][11]. Acousto-optic frequency shifters (AOFSs) deflect the light into a different spatial mode and shift its optical frequency by the acoustic frequency.…”